rcontrib with 2-phase method?

Dear Robert,

Thanks for making clear that using rcontrib and using 3/5 phase methods need a recent version of radiance. does that apply to using 2-phse (Daysim) or one can still use old versions of radiance (as I have a problem yet with installing recent versions of radiance and link it with Daysim tool)?

Many thanks for you in advance:

Regards,
ikriam

···

------------------------------

Message: 2
Date: Mon, 10 Aug 2015 17:03:49 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
        <[email protected]>
Subject: Re: [Radiance-general] Ray-tracing with Radiance
Message-ID: <D1EE1EEF.1B923%[email protected]>
Content-Type: text/plain; charset="us-ascii"

There is a daysim-specific mailing list that may be useful for some of your questions:

http://www.radiance-online.org/community/mailing-lists/subscribe/radiance-d
aysim

I can tell you that if you're planning to use rcontrib and do 3- or 5-phase type stuff, you definitely should be using a recent version of Radiance. Either build from latest source, or use one of the NREL pre-built packages (I recommend v5):

On 8/10/15, 9:14 AM, "Ikrima Amaireh" <[email protected]> wrote:

Dear Germ?n,

Many thanks for you. I agree with you totally that all Radiance works
need to apply ray-tracing approach as the core principle of it.
However, what I meant by using ray-tracing in radiance, was the using
of RTRACE directly through stand-alone radiance tool (as you kindly mentioned).

As you clarified, Daysim uses 2-phase method to do annual simulation
(2nd
phase) fast, based on pre-calculated Daylight Coefficient Matrix (1st
phase). Now, if I need to produce the illuminance levels (produced by
specific CFS) at the Workplane under static scene, can I still use
Daysim for that? Or, shall I stick to RTRACE tool directly through pure Radiance?

And, if I have to stick to using Pure Radiance (RTRACE), is the method
detailed in the attached document (hope, you see that: where Geometry
and Workplane sensors are built in Ecotect and directly exported to
Radiance engine), is it still valid?

Finally, in both cases (using pure Radiance and/or Daysim), shall we
replace the Radiance tool (works as engine) by the latest released
version (i.e. Version 4.2 or recent?) as the one works with
Ecotect-Radiance approach (I'm not sure about Daysim, yet) is old
version (2.0; in think!)?

Really, I am grateful to you for your appreciated help and looking to
hear from you again :slight_smile:

Regards,

Ikrima

As some of you may remember, I am trying to model a set of CFS to
compare their effect on indoor horizontal illuminance of a room.

So far, I have been advised by you for several stages, which really
helped me a lot for better understanding of radiance and how it works.
Now, I have a question about how I use ray-tracing method in radiance?
Is it similar to the way explained through the following attachment?
As here, calculations are run using Radiance engine but Ecotect or
Daysim interface (for geometry modelling and material assignment).
Document:
http://web.mit.edu/sustainabledesignlab/projects/TeachingResources/Gett
ing
StartedwithEcotectRadianceDaysim.pdf

I hope if you can kindly advise me on that asap, please?

Ikrima,

Strictly speaking, Radiance always use ray-tracing. Whenever you call
RPICT, RTRACE or RCONTRIB, there will always be a ray-tracing
simulation performed. However, when you want to perform annual
simulations, you will want to do as few ray-tracing simulations as
possible since they take time.
RTRACE, for example, is a method used to calculate the illuminance or
luminance of a point (sensor) in a static scene. Doing this for a whole
year would require 8760 or more RTRACE calls, which means 8760 or more
ray-tracing simulations, which is slow.

Accordingly, Daysim (which uses the 2-phase method) runs one
ray-tracing simulation that calculates the Daylight Coefficient matrix
(this can be done in pure radiance by using RCONTRIB). This matrix
relates the sensors
(workplane?) in the scene with the sky, mich means that you can modify
the sky and quickly evaluate illuminance in the same points. This
allows performing annual simulations fast (only the sky changes in a
static annual simulation). 3 and 5 phase method are extensions to this
that allow also modifying the CFSs in the scene.

Hope that clarify a little bit.

-----Original Message-----
From: [email protected]
[mailto:[email protected]]
Sent: 10 August 2015 14:20
To: [email protected]
Subject: Radiance-general Digest, Vol 138, Issue 12

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  1. Re: Ray-tracing with Radiance (Germ?n Molina Larrain)

----------------------------------------------------------------------

Message: 1
Date: Mon, 10 Aug 2015 10:19:18 -0300
From: Germ?n Molina Larrain <[email protected]>
To: Radiance general discussion <[email protected]>
Subject: Re: [Radiance-general] Ray-tracing with Radiance
Message-ID:

<CAF-iH4LVHB_V+Vmy-mSiv2EtUE25KDxtTAyJfao5Mi6fzFDU1g@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

Ikrima,

Strictly speaking, Radiance always use ray-tracing. Whenever you call
RPICT, RTRACE or RCONTRIB, there will always be a ray-tracing
simulation performed. However, when you want to perform annual
simulations, you will want to do as few ray-tracing simulations as
possible since they take time.
RTRACE, for example, is a method used to calculate the illuminance or
luminance of a point (sensor) in a static scene. Doing this for a whole
year would require 8760 or more RTRACE calls, which means 8760 or more
ray-tracing simulations, which is slow.

Accordingly, Daysim (which uses the 2-phase method) runs one
ray-tracing simulation that calculates the Daylight Coefficient matrix
(this can be done in pure radiance by using RCONTRIB). This matrix
relates the sensors
(workplane?) in the scene with the sky, mich means that you can modify
the sky and quickly evaluate illuminance in the same points. This
allows performing annual simulations fast (only the sky changes in a
static annual simulation). 3 and 5 phase method are extensions to this
that allow also modifying the CFSs in the scene.

Hope that clarify a little bit.

Best,

Germ?n

2015-08-10 8:51 GMT-03:00 Ikrima Amaireh <[email protected]>:

Hello Robert,
Hello all,

As some of you may remember, I am trying to model a set of CFS to
compare their effect on indoor horizontal illuminance of a room. So
far, I have been advised by you for several stages, which really
helped me a lot for better understanding of radiance and how it works.

Now, I have a question about how I use ray-tracing method in radiance?
Is it similar to the way explained through the following attachment?
As here, calculations are run using Radiance engine but Ecotect or
Daysim interface (for geometry modelling and material assignment).

Document:
http://web.mit.edu/sustainabledesignlab/projects/TeachingResources/Ge
t tingStartedwithEcotectRadianceDaysim.pdf

I hope if you can kindly advise me on that asap, please?

Best regards
Ikrima

-----Original Message-----
From: [email protected] [mailto:
[email protected]]
Sent: 12 July 2015 20:37
To: [email protected]
Subject: Radiance-general Digest, Vol 137, Issue 12

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        [email protected]

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Today's Topics:

   1. Git for Windows and starting tutorials (Ikrima Amaireh)

---------------------------------------------------------------------
-

Message: 1
Date: Sun, 12 Jul 2015 20:36:19 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
        <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] Git for Windows and starting tutorials
Message-ID:
        <
D697763F9F216044A99BC674C00561961358CA9C4C@EXCHANGE1.ad.nottingham.ac.
>

Content-Type: text/plain; charset="us-ascii"

Hi Robert,

Many thanks for your help.

I have installed Git for Windows as you adviced :slight_smile: Now, Before I
start with 3 or 5-phase tutorials, I'm thinking to go through
"radiance tutorial"
(by Axel Jacobs) as a beginner with almost a shallow
knowledge/experience of radiance. So, do recommend this (radiance
tutorial would be enough to start with 3 or 5-phase methods and
understanding of BSDF data approach,
etc) or advice another tutorial/source for better understanding of
radiance basics (using command prompt)?

Many thanks again :slight_smile:

Regards
Ikrima

------------------------------

Message: 2
Date: Fri, 10 Jul 2015 15:52:23 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
        <[email protected]>
Subject: Re: [Radiance-general] Radiance-general Digest, Vol 137,
        Issue 8
Message-ID: <D1C542EA.1AE88%[email protected]>
Content-Type: text/plain; charset="us-ascii"

OK so it sounds like you first tried the Windows installer
(presumably a NREL-provided one such as this:
https://github.com/NREL/Radiance/releases/download/5.0.a.3/radiance-5.
0.a-w in64.exe), and this most likely worked fine, you just had some
issues actually *doing* anything with it. This is normal. =)

I recommend you install Git for windows (https://msysgit.github.io/),
as that will add a little BASH emulator in your Windows system. This
way you can run most of the commands exactly as they appear in most
of the tutorials out there that are written from a UNIX perspective
(as you point out). If you run the "Git BASH shell" you will be able
to try out all the multi-phase methods, use and generate BSDFs, etc.
Once you have Git for Windows installed, head over to Andy McNeil's
tutorials for 3- and 5-phase, fire up the Git BASH shell (it'll be in
the Git program group in the Windows start menu), and get started!

One thing to keep in mind is that when running any commands that
read/write data (e.g. rcontrib), be sure to use ASCII format rather
than float. Windows has issues with float data (among many other
things).

Good luck!

- Rob

On 7/10/15, 8:08 AM, "Ikrima Amaireh" <[email protected]> wrote:

>Hi Robert,
>
>My PC is running on Windows 7 Enterprise.
>Initially, I installed Radiance for Window using its installer but I
>found that most of the tutorials are provided for pc with Linux
>and/or Linux-like operating systems; So I had to install try learnix
>(that did not work) and Ubuntu (also did not work)!
>Finally, I tried to use Cygwin to run Radiance on Window OS. I could
>install Cygwin (works fine), Xming (not sure if working) and
>Radiance (not all its programs are working!).
>
>I'm a bit confused as I'm not sure if running Radiance on windows
>using Cygwin will be enough for carrying my work. For example, can I
>work out phases methods and generate BSDF data?
>
>I wish if you can help me to do that.
>
>Many thanks
>ikrima
>
>
>
>------------------------------
>
>Message: 3
>Date: Thu, 9 Jul 2015 16:44:49 +0000
>From: "Guglielmetti, Robert" <[email protected]>
>To: "[email protected]"
> <[email protected]>
>Subject: Re: [Radiance-general] Could not install Radiance!!!
>Message-ID: <D1C400AC.1ADAC%[email protected]>
>Content-Type: text/plain; charset="us-ascii"
>
>Hi Ikrima,
>
>We'll need a bit more info, here. What OS are you on? How are you
>attempting to install it (using an installer, compiling from source,
>or what)? What happens when you try??
>
>On 7/9/15, 10:38 AM, "Ikrima Amaireh" <[email protected]> wrote:
>
>>Hi all,
>>
>>After one a few weeks of trying, I could not manage to install
>>radiance properly. I am almost disappointed! Please any help?
>>
>>Regards
>>Ikrima
>
>
>
>
>This message and any attachment are intended solely for the
>addressee and may contain confidential information. If you have
>received this message in error, please send it back to me, and immediately delete it.
>
>Please do not use, copy or disclose the information contained in
>this message or in any attachment. Any views or opinions expressed
>by the author of this email do not necessarily reflect the views of
>the University of Nottingham.
>
>This message has been checked for viruses but the contents of an
>attachment may still contain software viruses which could damage
>your computer system, you are advised to perform your own checks.
>Email communications with the University of Nottingham may be
>monitored as permitted by UK legislation.
>
>
>_______________________________________________
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>[email protected]
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------------------------------

Message: 3
Date: Fri, 10 Jul 2015 17:34:30 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
        <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] Modelling CFS
Message-ID:
        <
D697763F9F216044A99BC674C00561961358CA9BAF@EXCHANGE1.ad.nottingham.ac.
>

Content-Type: text/plain; charset="us-ascii"

Hi all,

Thanks Robert and Larrain for your detailed replies, that helped me a
lot.

I would summarise here what I got form your appreciated replies, as
following:
- Radiance is convenient and best of tools to model daylighting due
to its ray-tracing method.
- 3 or 5-phases methods are used to facilitate the calculations.
- Generating BSDF data is also used to facilitate these calculations
but it is limited to Klems resolution of some CFS.

Initially, I'm not planning to do annual calculations. It's just for
specific hours of the day and the target is to produce a illuminance
levels for indoor grid under different CFSs. Hence, according to my
understanding from Larrain words, I can use either 2-phase or
Ray-tracing methods. My question is how can I draw/define the CFS
geometry and Space for these calculations? Is it similar to the way
use in Ecotect/Radiance calculations?

Regards
Ikrima

-----Original Message-----
From: [email protected] [mailto:
[email protected]]
Sent: 09 July 2015 19:56
To: [email protected]
Subject: Radiance-general Digest, Vol 137, Issue 8

Send Radiance-general mailing list submissions to
        [email protected]

To subscribe or unsubscribe via the World Wide Web, visit

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        [email protected]

When replying, please edit your Subject line so it is more specific
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Today's Topics:

   1. CFS with Radiance (Ikrima Amaireh)
   2. Could not install Radiance!!! (Ikrima Amaireh)
   3. Re: Could not install Radiance!!! (Guglielmetti, Robert)
   4. Re: CFS with Radiance (Guglielmetti, Robert)
   5. Re: CFS with Radiance (Germ?n Molina Larrain)

---------------------------------------------------------------------
-

Message: 1
Date: Thu, 9 Jul 2015 17:26:29 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
        <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] CFS with Radiance
Message-ID:
        <
D697763F9F216044A99BC674C00561961358CA9710@EXCHANGE1.ad.nottingham.ac.
>

Content-Type: text/plain; charset="us-ascii"

Hi G. Larrain,

Thanks for your detailed clarification (below).

I wonder if you kindly can help me toward better understanding and
answering the following:

We agreed that for daylight modelling of spaces with CFS, Radiance is
a suitable tool as it applies ray-tracing method. And for annual
and/or climate-based daylight calculations, as calculation time
becomes a critical factor, using BSDF data for CFS is highly
recommended to tackle the task with radiance (using phases methods).
However:

- if someone needs to perform daylight calculations for given space
with different CFS (different cases for comparison purposes) to get
illumination levels for horizontal grid points (and not pictures nor
scenes), is Radiance still the most convenient option?
- is it still needed to use any of the phase methods (2, 3 or 5)?
- most importantly, is it still needed to get BSDF data for CFS or
just can model the detailed CFS in Radiance (and, if yes, how?)

Many thanks for your kind help :slight_smile:

Regards
Ikrima

"Ikrima,

I am going to try to build the puzzle of CFS, Phases, BSDF and
calculations.... at least the way I understand it.

*CFS* are those systems that, via interreflection or other light
transport phenomena, redirect light (or solar radiation). Thus, in
order to get a reliable result you will have to consider all the
phenomena involved.
Then, *common
simple performance indexes*, such as the miss-used Shading
Coefficient and the Aperture Percentage, *always loose a lot of
information, trying to reduce all the complex behavior of a CFS to
one single number*. We all know that venetian blinds are more
"transparent" from certain viewing directions than from others, but
these performance indexes do not tell you that.

Now... Radiance can certainly perform calculations of spaces with CFS
using its "common" Ray-tracing. However, this may be slow for some
purposes (i.e.
annual simulations and climate-based daylight modelling), and *this
is why 2, 3 and 5 phase methods have been developed*. The *BSDF*
representation, I would say, goes in the same direction... It allow
summarizing all the bounces, reflections, refractions, etc. that
occure withing the CFS in a single matrix or tensor.* By using
BSDFs*, Radiance itself and other tools (i.e. EnergyPlus) can treat
CFS as blackboxes, avoiding all the opcits within the system. A BSDF
that uses the Klems Full representation has
21,045 numbers (instead of one, such as the Shading Coefficient).

Being said all that, I would not trust a calculation method unless it
can actually deal with the optics of a CFS that is drawn and/or it
can use BSDF (or similar) information.

Lets remember that a perforated screen, a venetian blind, a light
diffusing device can all have a Shading Coefficient of 50%, but all
of them will behave very differently. I made some presentations about
this on my previous work (we sold complex Shading Devices), trying to
promote the use of BSDF in EnergyPlus calculations... the differences
(in solar heat gains) were more than considerable.

I hope that someone else gives us his/her perspective on this topic...
there are a lot of concepts that I might be misunderstanding.

Best!"

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University of Nottingham.

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------------------------------

Message: 2
Date: Thu, 9 Jul 2015 17:38:41 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
        <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] Could not install Radiance!!!
Message-ID:
        <
D697763F9F216044A99BC674C00561961358CA9719@EXCHANGE1.ad.nottingham.ac.
>

Content-Type: text/plain; charset="us-ascii"

Hi all,

After one a few weeks of trying, I could not manage to install
radiance properly. I am almost disappointed! Please any help?

Regards
Ikrima

This message and any attachment are intended solely for the addressee
and may contain confidential information. If you have received this
message in error, please send it back to me, and immediately delete it.

Please do not use, copy or disclose the information contained in this
message or in any attachment. Any views or opinions expressed by the
author of this email do not necessarily reflect the views of the
University of Nottingham.

This message has been checked for viruses but the contents of an
attachment may still contain software viruses which could damage your
computer system, you are advised to perform your own checks. Email
communications with the University of Nottingham may be monitored as
permitted by UK legislation.

------------------------------

Message: 3
Date: Thu, 9 Jul 2015 16:44:49 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
        <[email protected]>
Subject: Re: [Radiance-general] Could not install Radiance!!!
Message-ID: <D1C400AC.1ADAC%[email protected]>
Content-Type: text/plain; charset="us-ascii"

Hi Ikrima,

We'll need a bit more info, here. What OS are you on? How are you
attempting to install it (using an installer, compiling from source,
or what)? What happens when you try??

On 7/9/15, 10:38 AM, "Ikrima Amaireh" <[email protected]> wrote:

>Hi all,
>
>After one a few weeks of trying, I could not manage to install
>radiance properly. I am almost disappointed! Please any help?
>
>Regards
>Ikrima
>
>
>
>
>This message and any attachment are intended solely for the
>addressee and may contain confidential information. If you have
>received this message in error, please send it back to me, and immediately delete it.
>
>Please do not use, copy or disclose the information contained in
>this message or in any attachment. Any views or opinions expressed
>by the author of this email do not necessarily reflect the views of
>the University of Nottingham.
>
>This message has been checked for viruses but the contents of an
>attachment may still contain software viruses which could damage
>your computer system, you are advised to perform your own checks.
>Email communications with the University of Nottingham may be
>monitored as permitted by UK legislation.
>
>
>_______________________________________________
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>[email protected]
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------------------------------

Message: 4
Date: Thu, 9 Jul 2015 17:29:39 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
        <[email protected]>
Subject: Re: [Radiance-general] CFS with Radiance
Message-ID: <D1C40477.1ADCA%[email protected]>
Content-Type: text/plain; charset="us-ascii"

Some very quick replies and clarifications within:

On 7/9/15, 10:26 AM, "Ikrima Amaireh" <[email protected]> wrote:

>Hi G. Larrain,
>
>Thanks for your detailed clarification (below).
>
>I wonder if you kindly can help me toward better understanding and
>answering the following:
>
>We agreed that for daylight modelling of spaces with CFS, Radiance
>is a suitable tool as it applies ray-tracing method. And for annual
>and/or climate-based daylight calculations, as calculation time
>becomes a critical factor, using BSDF data for CFS is highly
>recommended to tackle the task with radiance (using phases methods).
However:

BSDF data in an annual simulation context is generally limited to
Klems basis BSDF data, which may not be high enough resolution for
some CFS. And the 5-phase method, which can circumvent this, is not
necessarily "quick".
This is all still very much a quandary and the newest daylight
metrics have added confusion to all of this, IMO.

>
>- if someone needs to perform daylight calculations for given space
>with different CFS (different cases for comparison purposes) to get
>illumination levels for horizontal grid points (and not pictures nor
>scenes), is Radiance still the most convenient option?

Absolutely. The lack of an image-as-output requirement does not
change the fact that ray tracing is a good/convenient algorithm
option for daylight simulation problems, especially when dealing with
diffusing media and CFS in general. BSDFs allow you to do lots of
"what-ifs", relatively quickly, but are beholden to the limitations
of the resolution of the BSDF.

>- is it still needed to use any of the phase methods (2, 3 or 5)?

Is what still needed? BSDF data? Ray tracing? I don't know of other
lighting simulation tools that can employ the multiphase methods. I
would say BSDF data is optional for 2-phase, required for 3-phase,
and optional for 5-phase.

>- most importantly, is it still needed to get BSDF data for CFS or
>just can model the detailed CFS in Radiance (and, if yes, how?)

Again I'm confused as to what "it" is. A couple of approaches are
available to you in general. If you have a geometric model of the CFS
you can use Radiance (genBSDF) to make a BSDF of the CFS and use that
in a 3- or 5-phase context. However in an annual/climate-based
simulation context, you will be stuck with a Klems basis BSDF and that
will not be very good resolution for a lot of CFS; here you may want
to use the 5-phase method and stick the actual CFS geometry in the
building model.

Some things to consider here are the photon map, now a part of
Radiance proper, or using the 2-phase method where appropriate. By
2-phase method I mean generating a daylight matrix for your
calculation points (or view), and modeling the window material as-is.
If the "CFS" is a shade cloth, you can approximate that with a
Radiance "trans". Same for translucent panels.
With this single daylight matrix, you can throw a vector of sky
matrices at it and get an annual climate-based result very quickly.
Problem is, we want to do stuff to the windows, sometimes at the time
step level, so:

Blinds and compact daylight redirection devices (e.g. Lightlouver)
are best represented as BSDF, and if most of the redirected flux is
headed up and away from the points of interest, a Klems basis BSDF is
good enough IMO. In these cases you could use the 3-phase method.
Problem is when you have a BSDF for blinds, and you also want to
simulate the blinds-up condition (i.e. clear, specularly transmitting
glass). Using a Klems basis BSDF for this is sub-optimal. You end up
needing to do two annual simulations, one as 2-phase for the clear
glass scenario, and again as a 3-phase (with a blinds BSDF for the
transmission
matrix) for the blinds down condition. If you have a lot of different
window groups, your simulation space can get large in a hurry. But
it's still do-able and you can get results that tell a story you
simply couldn't tell 5 years ago, informing the newest daylight
metrics as well.

------------------------------

Message: 5
Date: Thu, 9 Jul 2015 15:56:11 -0300
From: Germ?n Molina Larrain <[email protected]>
To: Radiance general discussion
<[email protected]>
Subject: Re: [Radiance-general] CFS with Radiance
Message-ID:
        <CAF-iH4LSr=y12F1khTrHh6hnf-kS=EmaFuo8uWKvHqMs=
[email protected]>
Content-Type: text/plain; charset="utf-8"

I must say that I agree with Rob, however, a short answer that might
help.

For evaluating illuminance levels in a space with different CFS you,
strictly speaking, DO NOT HAVE TO do anything. You may choose between
different methods that have some pros and cons.

*ray-tracing*

   - Requires ray-tracing for each time-step and each system, which
is slow
   (*four systems simulated annualy in an hourly basis --> 4*8760 =
35,040
   simulations*.)
   - As accurate as it gets, if options are defined correctly.

*2 phase method*

   - Do not need the BSDF
   - Requires ray-tracing for each CFS (*4 systems --> 4 ray-tracing
   simulations*)
   - After ray-tracing, annual simulation is fast.

*3-phase method:*

   - Requires BSDF data in KLEMS basis, which may be slow to compute,
   unless it can be exported from WINDOW, for example, or such data has
   already been calculated (the idea is to make a database, I think).
   - Does not really work well for specular systems (Klems patches
are too
   big)
   - Requires 2 ray-tracing runs, always (*4 systems --> 2 ray-tracing
   simulations*)
   - After ray-tracing and BSDF calculation, annual simulation is
fast

*5-phase method:*

   - Requires BSDF data in KLEMS basis AND/OR Tensor tree format, which
   may be slow to compute, unless it can be exported from WINDOW, for
example,
   or such data has already been calculated (the idea is to make a
database, I
   think).
   - Works well for specular systems
   - Requires 4 ray-tracing runs + 1 for each system, always (*4 systems
   --> 4+1 = 5 ray-tracing simulations*)
   - Hard to code...?
   - After ray-tracing and BSDF calculation, annual simulation is
fast

I would not say there is a recipe. If you have to choose between 1 or
2 CFSs, maybe it is faster to just draw them and use the 2 phase
method (or ray-tracing if an annual simulaton is not required). On
the contrary, if you are going to test 10 different CFSs, 3 and 5
phases may make sense, since you reduce the expensive ray-tracing
calculations... However, this will also depend on weather you have
the BSDF data AND/OR if it makes sense to calculate it and store it
AND/OR if you intend to simulate a dynamically controlled CFS.

Best!

2015-07-09 14:29 GMT-03:00 Guglielmetti, Robert <
[email protected]>:

> Some very quick replies and clarifications within:
>
> On 7/9/15, 10:26 AM, "Ikrima Amaireh" <[email protected]> wrote:
>
> >Hi G. Larrain,
> >
> >Thanks for your detailed clarification (below).
> >
> >I wonder if you kindly can help me toward better understanding and
> >answering the following:
> >
> >We agreed that for daylight modelling of spaces with CFS, Radiance
> >is a suitable tool as it applies ray-tracing method. And for
> >annual and/or climate-based daylight calculations, as calculation
> >time becomes a critical factor, using BSDF data for CFS is highly
> >recommended to tackle the task with radiance (using phases methods).
However:
>
>
> BSDF data in an annual simulation context is generally limited to
> Klems basis BSDF data, which may not be high enough resolution for
> some CFS. And the 5-phase method, which can circumvent this, is not
necessarily "quick".
> This is all still very much a quandary and the newest daylight
> metrics have added confusion to all of this, IMO.
>
>
> >
> >- if someone needs to perform daylight calculations for given
> >space with different CFS (different cases for comparison purposes)
> >to get illumination levels for horizontal grid points (and not
> >pictures nor scenes), is Radiance still the most convenient option?
>
>
> Absolutely. The lack of an image-as-output requirement does not
> change the fact that ray tracing is a good/convenient algorithm
> option for daylight simulation problems, especially when dealing
> with diffusing media and CFS in general. BSDFs allow you to do lots
> of "what-ifs", relatively quickly, but are beholden to the
> limitations of the
resolution of the BSDF.
>
>
> >- is it still needed to use any of the phase methods (2, 3 or 5)?
>
>
> Is what still needed? BSDF data? Ray tracing? I don't know of other
> lighting simulation tools that can employ the multiphase methods. I
> would say BSDF data is optional for 2-phase, required for 3-phase,
> and optional for 5-phase.
>
> >- most importantly, is it still needed to get BSDF data for CFS or
> >just can model the detailed CFS in Radiance (and, if yes, how?)
>
>
> Again I'm confused as to what "it" is. A couple of approaches are
> available to you in general. If you have a geometric model of the
> CFS you can use Radiance (genBSDF) to make a BSDF of the CFS and
> use that in a 3- or 5-phase context. However in an
> annual/climate-based simulation context, you will be stuck with a
> Klems basis BSDF and that will not be very good resolution for a
> lot of CFS; here you may want to use the 5-phase method and stick
> the actual CFS geometry in the
building model.
>
> Some things to consider here are the photon map, now a part of
> Radiance proper, or using the 2-phase method where appropriate. By
> 2-phase method I mean generating a daylight matrix for your
> calculation points (or view), and modeling the window material as-is.
> If the "CFS" is a shade cloth, you can approximate that with a
> Radiance
"trans". Same for translucent panels.
> With this single daylight matrix, you can throw a vector of sky
> matrices at it and get an annual climate-based result very quickly.
> Problem is, we want to do stuff to the windows, sometimes at the
> time
step level, so:
>
> Blinds and compact daylight redirection devices (e.g. Lightlouver)
> are best represented as BSDF, and if most of the redirected flux is
> headed up and away from the points of interest, a Klems basis BSDF
> is good enough IMO. In these cases you could use the 3-phase method.
> Problem is when you have a BSDF for blinds, and you also want to
> simulate the blinds-up condition (i.e. clear, specularly
> transmitting glass). Using a Klems basis BSDF for this is
> sub-optimal. You end up needing to do two annual simulations, one
> as 2-phase for the clear glass scenario, and again as a 3-phase
> (with a blinds BSDF for the transmission
> matrix) for the blinds down condition. If you have a lot of
> different window groups, your simulation space can get large in a
> hurry. But it's still do-able and you can get results that tell a
> story you simply couldn't tell 5 years ago, informing the newest
> daylight metrics
as well.
>
>
>
>
> _______________________________________________
> Radiance-general mailing list
> [email protected]
> http://www.radiance-online.org/mailman/listinfo/radiance-general
>
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I really have no experience with Daysim at this point so I really am not
the best person to answer this one, sorry. In a general sense, with
respect to Daysim and Radiance you'd use one or the other, not both. The
Radiance daylight coefficient method (i.e. using rcontrib and other tools
in Radiance to do a 2-phase annual simulation) *is* basically the same
thing as Daysim. Hope this helps but it probably doesn't. =/

···

On 8/11/15, 4:54 AM, "Ikrima Amaireh" <[email protected]> wrote:

Dear Robert,

Thanks for making clear that using rcontrib and using 3/5 phase methods
need a recent version of radiance. does that apply to using 2-phse
(Daysim) or one can still use old versions of radiance (as I have a
problem yet with installing recent versions of radiance and link it with
Daysim tool)?

Many thanks for you in advance:

Regards,
ikriam

------------------------------

Message: 2
Date: Mon, 10 Aug 2015 17:03:49 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
       <[email protected]>
Subject: Re: [Radiance-general] Ray-tracing with Radiance
Message-ID: <D1EE1EEF.1B923%[email protected]>
Content-Type: text/plain; charset="us-ascii"

There is a daysim-specific mailing list that may be useful for some of
your questions:

http://www.radiance-online.org/community/mailing-lists/subscribe/radiance-
d
aysim

I can tell you that if you're planning to use rcontrib and do 3- or
5-phase type stuff, you definitely should be using a recent version of
Radiance. Either build from latest source, or use one of the NREL
pre-built packages (I recommend v5):

https://github.com/NREL/Radiance/releases/tag/5.0.a.3

On 8/10/15, 9:14 AM, "Ikrima Amaireh" <[email protected]> wrote:

Dear Germ?n,

Many thanks for you. I agree with you totally that all Radiance works
need to apply ray-tracing approach as the core principle of it.
However, what I meant by using ray-tracing in radiance, was the using
of RTRACE directly through stand-alone radiance tool (as you kindly
mentioned).

As you clarified, Daysim uses 2-phase method to do annual simulation
(2nd
phase) fast, based on pre-calculated Daylight Coefficient Matrix (1st
phase). Now, if I need to produce the illuminance levels (produced by
specific CFS) at the Workplane under static scene, can I still use
Daysim for that? Or, shall I stick to RTRACE tool directly through pure
Radiance?

And, if I have to stick to using Pure Radiance (RTRACE), is the method
detailed in the attached document (hope, you see that: where Geometry
and Workplane sensors are built in Ecotect and directly exported to
Radiance engine), is it still valid?

Finally, in both cases (using pure Radiance and/or Daysim), shall we
replace the Radiance tool (works as engine) by the latest released
version (i.e. Version 4.2 or recent?) as the one works with
Ecotect-Radiance approach (I'm not sure about Daysim, yet) is old
version (2.0; in think!)?

Really, I am grateful to you for your appreciated help and looking to
hear from you again :slight_smile:

Regards,

Ikrima

As some of you may remember, I am trying to model a set of CFS to
compare their effect on indoor horizontal illuminance of a room.

So far, I have been advised by you for several stages, which really
helped me a lot for better understanding of radiance and how it works.
Now, I have a question about how I use ray-tracing method in radiance?
Is it similar to the way explained through the following attachment?
As here, calculations are run using Radiance engine but Ecotect or
Daysim interface (for geometry modelling and material assignment).
Document:
http://web.mit.edu/sustainabledesignlab/projects/TeachingResources/Gett
ing
StartedwithEcotectRadianceDaysim.pdf

I hope if you can kindly advise me on that asap, please?

Ikrima,

Strictly speaking, Radiance always use ray-tracing. Whenever you call
RPICT, RTRACE or RCONTRIB, there will always be a ray-tracing
simulation performed. However, when you want to perform annual
simulations, you will want to do as few ray-tracing simulations as
possible since they take time.
RTRACE, for example, is a method used to calculate the illuminance or
luminance of a point (sensor) in a static scene. Doing this for a whole
year would require 8760 or more RTRACE calls, which means 8760 or more
ray-tracing simulations, which is slow.

Accordingly, Daysim (which uses the 2-phase method) runs one
ray-tracing simulation that calculates the Daylight Coefficient matrix
(this can be done in pure radiance by using RCONTRIB). This matrix
relates the sensors
(workplane?) in the scene with the sky, mich means that you can modify
the sky and quickly evaluate illuminance in the same points. This
allows performing annual simulations fast (only the sky changes in a
static annual simulation). 3 and 5 phase method are extensions to this
that allow also modifying the CFSs in the scene.

Hope that clarify a little bit.

-----Original Message-----
From: [email protected]
[mailto:[email protected]]
Sent: 10 August 2015 14:20
To: [email protected]
Subject: Radiance-general Digest, Vol 138, Issue 12

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  1. Re: Ray-tracing with Radiance (Germ?n Molina Larrain)

----------------------------------------------------------------------

Message: 1
Date: Mon, 10 Aug 2015 10:19:18 -0300
From: Germ?n Molina Larrain <[email protected]>
To: Radiance general discussion <[email protected]>
Subject: Re: [Radiance-general] Ray-tracing with Radiance
Message-ID:

<CAF-iH4LVHB_V+Vmy-mSiv2EtUE25KDxtTAyJfao5Mi6fzFDU1g@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

Ikrima,

Strictly speaking, Radiance always use ray-tracing. Whenever you call
RPICT, RTRACE or RCONTRIB, there will always be a ray-tracing
simulation performed. However, when you want to perform annual
simulations, you will want to do as few ray-tracing simulations as
possible since they take time.
RTRACE, for example, is a method used to calculate the illuminance or
luminance of a point (sensor) in a static scene. Doing this for a whole
year would require 8760 or more RTRACE calls, which means 8760 or more
ray-tracing simulations, which is slow.

Accordingly, Daysim (which uses the 2-phase method) runs one
ray-tracing simulation that calculates the Daylight Coefficient matrix
(this can be done in pure radiance by using RCONTRIB). This matrix
relates the sensors
(workplane?) in the scene with the sky, mich means that you can modify
the sky and quickly evaluate illuminance in the same points. This
allows performing annual simulations fast (only the sky changes in a
static annual simulation). 3 and 5 phase method are extensions to this
that allow also modifying the CFSs in the scene.

Hope that clarify a little bit.

Best,

Germ?n

2015-08-10 8:51 GMT-03:00 Ikrima Amaireh <[email protected]>:

Hello Robert,
Hello all,

As some of you may remember, I am trying to model a set of CFS to
compare their effect on indoor horizontal illuminance of a room. So
far, I have been advised by you for several stages, which really
helped me a lot for better understanding of radiance and how it works.

Now, I have a question about how I use ray-tracing method in radiance?
Is it similar to the way explained through the following attachment?
As here, calculations are run using Radiance engine but Ecotect or
Daysim interface (for geometry modelling and material assignment).

Document:
http://web.mit.edu/sustainabledesignlab/projects/TeachingResources/Ge
t tingStartedwithEcotectRadianceDaysim.pdf

I hope if you can kindly advise me on that asap, please?

Best regards
Ikrima

-----Original Message-----
From: [email protected] [mailto:
[email protected]]
Sent: 12 July 2015 20:37
To: [email protected]
Subject: Radiance-general Digest, Vol 137, Issue 12

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   1. Git for Windows and starting tutorials (Ikrima Amaireh)

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Message: 1
Date: Sun, 12 Jul 2015 20:36:19 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
        <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] Git for Windows and starting tutorials
Message-ID:
        <
D697763F9F216044A99BC674C00561961358CA9C4C@EXCHANGE1.ad.nottingham.ac.
>

Content-Type: text/plain; charset="us-ascii"

Hi Robert,

Many thanks for your help.

I have installed Git for Windows as you adviced :slight_smile: Now, Before I
start with 3 or 5-phase tutorials, I'm thinking to go through
"radiance tutorial"
(by Axel Jacobs) as a beginner with almost a shallow
knowledge/experience of radiance. So, do recommend this (radiance
tutorial would be enough to start with 3 or 5-phase methods and
understanding of BSDF data approach,
etc) or advice another tutorial/source for better understanding of
radiance basics (using command prompt)?

Many thanks again :slight_smile:

Regards
Ikrima

------------------------------

Message: 2
Date: Fri, 10 Jul 2015 15:52:23 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
        <[email protected]>
Subject: Re: [Radiance-general] Radiance-general Digest, Vol 137,
        Issue 8
Message-ID: <D1C542EA.1AE88%[email protected]>
Content-Type: text/plain; charset="us-ascii"

OK so it sounds like you first tried the Windows installer
(presumably a NREL-provided one such as this:
https://github.com/NREL/Radiance/releases/download/5.0.a.3/radiance-5.
0.a-w in64.exe), and this most likely worked fine, you just had some
issues actually *doing* anything with it. This is normal. =)

I recommend you install Git for windows (https://msysgit.github.io/),
as that will add a little BASH emulator in your Windows system. This
way you can run most of the commands exactly as they appear in most
of the tutorials out there that are written from a UNIX perspective
(as you point out). If you run the "Git BASH shell" you will be able
to try out all the multi-phase methods, use and generate BSDFs, etc.
Once you have Git for Windows installed, head over to Andy McNeil's
tutorials for 3- and 5-phase, fire up the Git BASH shell (it'll be in
the Git program group in the Windows start menu), and get started!

One thing to keep in mind is that when running any commands that
read/write data (e.g. rcontrib), be sure to use ASCII format rather
than float. Windows has issues with float data (among many other
things).

Good luck!

- Rob

On 7/10/15, 8:08 AM, "Ikrima Amaireh" <[email protected]> wrote:

>Hi Robert,
>
>My PC is running on Windows 7 Enterprise.
>Initially, I installed Radiance for Window using its installer but I
>found that most of the tutorials are provided for pc with Linux
>and/or Linux-like operating systems; So I had to install try learnix
>(that did not work) and Ubuntu (also did not work)!
>Finally, I tried to use Cygwin to run Radiance on Window OS. I could
>install Cygwin (works fine), Xming (not sure if working) and
>Radiance (not all its programs are working!).
>
>I'm a bit confused as I'm not sure if running Radiance on windows
>using Cygwin will be enough for carrying my work. For example, can I
>work out phases methods and generate BSDF data?
>
>I wish if you can help me to do that.
>
>Many thanks
>ikrima
>
>
>
>------------------------------
>
>Message: 3
>Date: Thu, 9 Jul 2015 16:44:49 +0000
>From: "Guglielmetti, Robert" <[email protected]>
>To: "[email protected]"
> <[email protected]>
>Subject: Re: [Radiance-general] Could not install Radiance!!!
>Message-ID: <D1C400AC.1ADAC%[email protected]>
>Content-Type: text/plain; charset="us-ascii"
>
>Hi Ikrima,
>
>We'll need a bit more info, here. What OS are you on? How are you
>attempting to install it (using an installer, compiling from source,
>or what)? What happens when you try??
>
>On 7/9/15, 10:38 AM, "Ikrima Amaireh" <[email protected]> wrote:
>
>>Hi all,
>>
>>After one a few weeks of trying, I could not manage to install
>>radiance properly. I am almost disappointed! Please any help?
>>
>>Regards
>>Ikrima
>
>
>
>
>This message and any attachment are intended solely for the
>addressee and may contain confidential information. If you have
>received this message in error, please send it back to me, and
immediately delete it.
>
>Please do not use, copy or disclose the information contained in
>this message or in any attachment. Any views or opinions expressed
>by the author of this email do not necessarily reflect the views of
>the University of Nottingham.
>
>This message has been checked for viruses but the contents of an
>attachment may still contain software viruses which could damage
>your computer system, you are advised to perform your own checks.
>Email communications with the University of Nottingham may be
>monitored as permitted by UK legislation.
>
>
>_______________________________________________
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------------------------------

Message: 3
Date: Fri, 10 Jul 2015 17:34:30 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
        <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] Modelling CFS
Message-ID:
        <
D697763F9F216044A99BC674C00561961358CA9BAF@EXCHANGE1.ad.nottingham.ac.
>

Content-Type: text/plain; charset="us-ascii"

Hi all,

Thanks Robert and Larrain for your detailed replies, that helped me a
lot.

I would summarise here what I got form your appreciated replies, as
following:
- Radiance is convenient and best of tools to model daylighting due
to its ray-tracing method.
- 3 or 5-phases methods are used to facilitate the calculations.
- Generating BSDF data is also used to facilitate these calculations
but it is limited to Klems resolution of some CFS.

Initially, I'm not planning to do annual calculations. It's just for
specific hours of the day and the target is to produce a illuminance
levels for indoor grid under different CFSs. Hence, according to my
understanding from Larrain words, I can use either 2-phase or
Ray-tracing methods. My question is how can I draw/define the CFS
geometry and Space for these calculations? Is it similar to the way
use in Ecotect/Radiance calculations?

Regards
Ikrima

-----Original Message-----
From: [email protected] [mailto:
[email protected]]
Sent: 09 July 2015 19:56
To: [email protected]
Subject: Radiance-general Digest, Vol 137, Issue 8

Send Radiance-general mailing list submissions to
        [email protected]

To subscribe or unsubscribe via the World Wide Web, visit

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        [email protected]

When replying, please edit your Subject line so it is more specific
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"Re: Contents of Radiance-general digest..."

Today's Topics:

   1. CFS with Radiance (Ikrima Amaireh)
   2. Could not install Radiance!!! (Ikrima Amaireh)
   3. Re: Could not install Radiance!!! (Guglielmetti, Robert)
   4. Re: CFS with Radiance (Guglielmetti, Robert)
   5. Re: CFS with Radiance (Germ?n Molina Larrain)

---------------------------------------------------------------------
-

Message: 1
Date: Thu, 9 Jul 2015 17:26:29 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
        <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] CFS with Radiance
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D697763F9F216044A99BC674C00561961358CA9710@EXCHANGE1.ad.nottingham.ac.
>

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Hi G. Larrain,

Thanks for your detailed clarification (below).

I wonder if you kindly can help me toward better understanding and
answering the following:

We agreed that for daylight modelling of spaces with CFS, Radiance is
a suitable tool as it applies ray-tracing method. And for annual
and/or climate-based daylight calculations, as calculation time
becomes a critical factor, using BSDF data for CFS is highly
recommended to tackle the task with radiance (using phases methods).
However:

- if someone needs to perform daylight calculations for given space
with different CFS (different cases for comparison purposes) to get
illumination levels for horizontal grid points (and not pictures nor
scenes), is Radiance still the most convenient option?
- is it still needed to use any of the phase methods (2, 3 or 5)?
- most importantly, is it still needed to get BSDF data for CFS or
just can model the detailed CFS in Radiance (and, if yes, how?)

Many thanks for your kind help :slight_smile:

Regards
Ikrima

"Ikrima,

I am going to try to build the puzzle of CFS, Phases, BSDF and
calculations.... at least the way I understand it.

*CFS* are those systems that, via interreflection or other light
transport phenomena, redirect light (or solar radiation). Thus, in
order to get a reliable result you will have to consider all the
phenomena involved.
Then, *common
simple performance indexes*, such as the miss-used Shading
Coefficient and the Aperture Percentage, *always loose a lot of
information, trying to reduce all the complex behavior of a CFS to
one single number*. We all know that venetian blinds are more
"transparent" from certain viewing directions than from others, but
these performance indexes do not tell you that.

Now... Radiance can certainly perform calculations of spaces with CFS
using its "common" Ray-tracing. However, this may be slow for some
purposes (i.e.
annual simulations and climate-based daylight modelling), and *this
is why 2, 3 and 5 phase methods have been developed*. The *BSDF*
representation, I would say, goes in the same direction... It allow
summarizing all the bounces, reflections, refractions, etc. that
occure withing the CFS in a single matrix or tensor.* By using
BSDFs*, Radiance itself and other tools (i.e. EnergyPlus) can treat
CFS as blackboxes, avoiding all the opcits within the system. A BSDF
that uses the Klems Full representation has
21,045 numbers (instead of one, such as the Shading Coefficient).

Being said all that, I would not trust a calculation method unless it
can actually deal with the optics of a CFS that is drawn and/or it
can use BSDF (or similar) information.

Lets remember that a perforated screen, a venetian blind, a light
diffusing device can all have a Shading Coefficient of 50%, but all
of them will behave very differently. I made some presentations about
this on my previous work (we sold complex Shading Devices), trying to
promote the use of BSDF in EnergyPlus calculations... the differences
(in solar heat gains) were more than considerable.

I hope that someone else gives us his/her perspective on this topic...
there are a lot of concepts that I might be misunderstanding.

Best!"

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Message: 2
Date: Thu, 9 Jul 2015 17:38:41 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
        <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] Could not install Radiance!!!
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Hi all,

After one a few weeks of trying, I could not manage to install
radiance properly. I am almost disappointed! Please any help?

Regards
Ikrima

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Message: 3
Date: Thu, 9 Jul 2015 16:44:49 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
        <[email protected]>
Subject: Re: [Radiance-general] Could not install Radiance!!!
Message-ID: <D1C400AC.1ADAC%[email protected]>
Content-Type: text/plain; charset="us-ascii"

Hi Ikrima,

We'll need a bit more info, here. What OS are you on? How are you
attempting to install it (using an installer, compiling from source,
or what)? What happens when you try??

On 7/9/15, 10:38 AM, "Ikrima Amaireh" <[email protected]> wrote:

>Hi all,
>
>After one a few weeks of trying, I could not manage to install
>radiance properly. I am almost disappointed! Please any help?
>
>Regards
>Ikrima
>
>
>
>
>This message and any attachment are intended solely for the
>addressee and may contain confidential information. If you have
>received this message in error, please send it back to me, and
immediately delete it.
>
>Please do not use, copy or disclose the information contained in
>this message or in any attachment. Any views or opinions expressed
>by the author of this email do not necessarily reflect the views of
>the University of Nottingham.
>
>This message has been checked for viruses but the contents of an
>attachment may still contain software viruses which could damage
>your computer system, you are advised to perform your own checks.
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>monitored as permitted by UK legislation.
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------------------------------

Message: 4
Date: Thu, 9 Jul 2015 17:29:39 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
        <[email protected]>
Subject: Re: [Radiance-general] CFS with Radiance
Message-ID: <D1C40477.1ADCA%[email protected]>
Content-Type: text/plain; charset="us-ascii"

Some very quick replies and clarifications within:

On 7/9/15, 10:26 AM, "Ikrima Amaireh" <[email protected]> wrote:

>Hi G. Larrain,
>
>Thanks for your detailed clarification (below).
>
>I wonder if you kindly can help me toward better understanding and
>answering the following:
>
>We agreed that for daylight modelling of spaces with CFS, Radiance
>is a suitable tool as it applies ray-tracing method. And for annual
>and/or climate-based daylight calculations, as calculation time
>becomes a critical factor, using BSDF data for CFS is highly
>recommended to tackle the task with radiance (using phases methods).
However:

BSDF data in an annual simulation context is generally limited to
Klems basis BSDF data, which may not be high enough resolution for
some CFS. And the 5-phase method, which can circumvent this, is not
necessarily "quick".
This is all still very much a quandary and the newest daylight
metrics have added confusion to all of this, IMO.

>
>- if someone needs to perform daylight calculations for given space
>with different CFS (different cases for comparison purposes) to get
>illumination levels for horizontal grid points (and not pictures nor
>scenes), is Radiance still the most convenient option?

Absolutely. The lack of an image-as-output requirement does not
change the fact that ray tracing is a good/convenient algorithm
option for daylight simulation problems, especially when dealing with
diffusing media and CFS in general. BSDFs allow you to do lots of
"what-ifs", relatively quickly, but are beholden to the limitations
of the resolution of the BSDF.

>- is it still needed to use any of the phase methods (2, 3 or 5)?

Is what still needed? BSDF data? Ray tracing? I don't know of other
lighting simulation tools that can employ the multiphase methods. I
would say BSDF data is optional for 2-phase, required for 3-phase,
and optional for 5-phase.

>- most importantly, is it still needed to get BSDF data for CFS or
>just can model the detailed CFS in Radiance (and, if yes, how?)

Again I'm confused as to what "it" is. A couple of approaches are
available to you in general. If you have a geometric model of the CFS
you can use Radiance (genBSDF) to make a BSDF of the CFS and use that
in a 3- or 5-phase context. However in an annual/climate-based
simulation context, you will be stuck with a Klems basis BSDF and that
will not be very good resolution for a lot of CFS; here you may want
to use the 5-phase method and stick the actual CFS geometry in the
building model.

Some things to consider here are the photon map, now a part of
Radiance proper, or using the 2-phase method where appropriate. By
2-phase method I mean generating a daylight matrix for your
calculation points (or view), and modeling the window material as-is.
If the "CFS" is a shade cloth, you can approximate that with a
Radiance "trans". Same for translucent panels.
With this single daylight matrix, you can throw a vector of sky
matrices at it and get an annual climate-based result very quickly.
Problem is, we want to do stuff to the windows, sometimes at the time
step level, so:

Blinds and compact daylight redirection devices (e.g. Lightlouver)
are best represented as BSDF, and if most of the redirected flux is
headed up and away from the points of interest, a Klems basis BSDF is
good enough IMO. In these cases you could use the 3-phase method.
Problem is when you have a BSDF for blinds, and you also want to
simulate the blinds-up condition (i.e. clear, specularly transmitting
glass). Using a Klems basis BSDF for this is sub-optimal. You end up
needing to do two annual simulations, one as 2-phase for the clear
glass scenario, and again as a 3-phase (with a blinds BSDF for the
transmission
matrix) for the blinds down condition. If you have a lot of different
window groups, your simulation space can get large in a hurry. But
it's still do-able and you can get results that tell a story you
simply couldn't tell 5 years ago, informing the newest daylight
metrics as well.

------------------------------

Message: 5
Date: Thu, 9 Jul 2015 15:56:11 -0300
From: Germ?n Molina Larrain <[email protected]>
To: Radiance general discussion
<[email protected]>
Subject: Re: [Radiance-general] CFS with Radiance
Message-ID:
        <CAF-iH4LSr=y12F1khTrHh6hnf-kS=EmaFuo8uWKvHqMs=
[email protected]>
Content-Type: text/plain; charset="utf-8"

I must say that I agree with Rob, however, a short answer that might
help.

For evaluating illuminance levels in a space with different CFS you,
strictly speaking, DO NOT HAVE TO do anything. You may choose between
different methods that have some pros and cons.

*ray-tracing*

   - Requires ray-tracing for each time-step and each system, which
is slow
   (*four systems simulated annualy in an hourly basis --> 4*8760 =
35,040
   simulations*.)
   - As accurate as it gets, if options are defined correctly.

*2 phase method*

   - Do not need the BSDF
   - Requires ray-tracing for each CFS (*4 systems --> 4 ray-tracing
   simulations*)
   - After ray-tracing, annual simulation is fast.

*3-phase method:*

   - Requires BSDF data in KLEMS basis, which may be slow to compute,
   unless it can be exported from WINDOW, for example, or such data has
   already been calculated (the idea is to make a database, I think).
   - Does not really work well for specular systems (Klems patches
are too
   big)
   - Requires 2 ray-tracing runs, always (*4 systems --> 2 ray-tracing
   simulations*)
   - After ray-tracing and BSDF calculation, annual simulation is
fast

*5-phase method:*

   - Requires BSDF data in KLEMS basis AND/OR Tensor tree format,
which
   may be slow to compute, unless it can be exported from WINDOW, for
example,
   or such data has already been calculated (the idea is to make a
database, I
   think).
   - Works well for specular systems
   - Requires 4 ray-tracing runs + 1 for each system, always (*4
systems
   --> 4+1 = 5 ray-tracing simulations*)
   - Hard to code...?
   - After ray-tracing and BSDF calculation, annual simulation is
fast

I would not say there is a recipe. If you have to choose between 1 or
2 CFSs, maybe it is faster to just draw them and use the 2 phase
method (or ray-tracing if an annual simulaton is not required). On
the contrary, if you are going to test 10 different CFSs, 3 and 5
phases may make sense, since you reduce the expensive ray-tracing
calculations... However, this will also depend on weather you have
the BSDF data AND/OR if it makes sense to calculate it and store it
AND/OR if you intend to simulate a dynamically controlled CFS.

Best!

2015-07-09 14:29 GMT-03:00 Guglielmetti, Robert <
[email protected]>:

> Some very quick replies and clarifications within:
>
> On 7/9/15, 10:26 AM, "Ikrima Amaireh" <[email protected]> wrote:
>
> >Hi G. Larrain,
> >
> >Thanks for your detailed clarification (below).
> >
> >I wonder if you kindly can help me toward better understanding and
> >answering the following:
> >
> >We agreed that for daylight modelling of spaces with CFS, Radiance
> >is a suitable tool as it applies ray-tracing method. And for
> >annual and/or climate-based daylight calculations, as calculation
> >time becomes a critical factor, using BSDF data for CFS is highly
> >recommended to tackle the task with radiance (using phases methods).
However:
>
>
> BSDF data in an annual simulation context is generally limited to
> Klems basis BSDF data, which may not be high enough resolution for
> some CFS. And the 5-phase method, which can circumvent this, is not
necessarily "quick".
> This is all still very much a quandary and the newest daylight
> metrics have added confusion to all of this, IMO.
>
>
> >
> >- if someone needs to perform daylight calculations for given
> >space with different CFS (different cases for comparison purposes)
> >to get illumination levels for horizontal grid points (and not
> >pictures nor scenes), is Radiance still the most convenient option?
>
>
> Absolutely. The lack of an image-as-output requirement does not
> change the fact that ray tracing is a good/convenient algorithm
> option for daylight simulation problems, especially when dealing
> with diffusing media and CFS in general. BSDFs allow you to do lots
> of "what-ifs", relatively quickly, but are beholden to the
> limitations of the
resolution of the BSDF.
>
>
> >- is it still needed to use any of the phase methods (2, 3 or 5)?
>
>
> Is what still needed? BSDF data? Ray tracing? I don't know of other
> lighting simulation tools that can employ the multiphase methods. I
> would say BSDF data is optional for 2-phase, required for 3-phase,
> and optional for 5-phase.
>
> >- most importantly, is it still needed to get BSDF data for CFS or
> >just can model the detailed CFS in Radiance (and, if yes, how?)
>
>
> Again I'm confused as to what "it" is. A couple of approaches are
> available to you in general. If you have a geometric model of the
> CFS you can use Radiance (genBSDF) to make a BSDF of the CFS and
> use that in a 3- or 5-phase context. However in an
> annual/climate-based simulation context, you will be stuck with a
> Klems basis BSDF and that will not be very good resolution for a
> lot of CFS; here you may want to use the 5-phase method and stick
> the actual CFS geometry in the
building model.
>
> Some things to consider here are the photon map, now a part of
> Radiance proper, or using the 2-phase method where appropriate. By
> 2-phase method I mean generating a daylight matrix for your
> calculation points (or view), and modeling the window material as-is.
> If the "CFS" is a shade cloth, you can approximate that with a
> Radiance
"trans". Same for translucent panels.
> With this single daylight matrix, you can throw a vector of sky
> matrices at it and get an annual climate-based result very quickly.
> Problem is, we want to do stuff to the windows, sometimes at the
> time
step level, so:
>
> Blinds and compact daylight redirection devices (e.g. Lightlouver)
> are best represented as BSDF, and if most of the redirected flux is
> headed up and away from the points of interest, a Klems basis BSDF
> is good enough IMO. In these cases you could use the 3-phase method.
> Problem is when you have a BSDF for blinds, and you also want to
> simulate the blinds-up condition (i.e. clear, specularly
> transmitting glass). Using a Klems basis BSDF for this is
> sub-optimal. You end up needing to do two annual simulations, one
> as 2-phase for the clear glass scenario, and again as a 3-phase
> (with a blinds BSDF for the transmission
> matrix) for the blinds down condition. If you have a lot of
> different window groups, your simulation space can get large in a
> hurry. But it's still do-able and you can get results that tell a
> story you simply couldn't tell 5 years ago, informing the newest
> daylight metrics
as well.
>
>
>
>
> _______________________________________________
> Radiance-general mailing list
> [email protected]
> http://www.radiance-online.org/mailman/listinfo/radiance-general
>
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Dear Ikrima,

Daysim comes with its own special version of the Radiance binaries that can be downloaded at the Daysim website <http://daysim.ning.com/>. These get stored in c:\DAYSIM\bin\ after installation on Windows. Unfortunately the binaries are based on an older Radiance version, so you miss some options like using BSDF data. Still, Daysim is perfectly serviceable for most cases. I hope I understood your question.

Best,
Alstan

···

On 8/11/2015 11:09 PM, Guglielmetti, Robert wrote:

I really have no experience with Daysim at this point so I really am not
the best person to answer this one, sorry. In a general sense, with
respect to Daysim and Radiance you'd use one or the other, not both. The
Radiance daylight coefficient method (i.e. using rcontrib and other tools
in Radiance to do a 2-phase annual simulation) *is* basically the same
thing as Daysim. Hope this helps but it probably doesn't. =/

On 8/11/15, 4:54 AM, "Ikrima Amaireh" <[email protected]> wrote:

Dear Robert,

Thanks for making clear that using rcontrib and using 3/5 phase methods
need a recent version of radiance. does that apply to using 2-phse
(Daysim) or one can still use old versions of radiance (as I have a
problem yet with installing recent versions of radiance and link it with
Daysim tool)?

Many thanks for you in advance:

Regards,
ikriam

------------------------------

Message: 2
Date: Mon, 10 Aug 2015 17:03:49 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
        <[email protected]>
Subject: Re: [Radiance-general] Ray-tracing with Radiance
Message-ID: <D1EE1EEF.1B923%[email protected]>
Content-Type: text/plain; charset="us-ascii"

There is a daysim-specific mailing list that may be useful for some of
your questions:

http://www.radiance-online.org/community/mailing-lists/subscribe/radiance-
d
aysim

I can tell you that if you're planning to use rcontrib and do 3- or
5-phase type stuff, you definitely should be using a recent version of
Radiance. Either build from latest source, or use one of the NREL
pre-built packages (I recommend v5):

https://github.com/NREL/Radiance/releases/tag/5.0.a.3

On 8/10/15, 9:14 AM, "Ikrima Amaireh" <[email protected]> wrote:

Dear Germ?n,

Many thanks for you. I agree with you totally that all Radiance works
need to apply ray-tracing approach as the core principle of it.
However, what I meant by using ray-tracing in radiance, was the using
of RTRACE directly through stand-alone radiance tool (as you kindly
mentioned).

As you clarified, Daysim uses 2-phase method to do annual simulation
(2nd
phase) fast, based on pre-calculated Daylight Coefficient Matrix (1st
phase). Now, if I need to produce the illuminance levels (produced by
specific CFS) at the Workplane under static scene, can I still use
Daysim for that? Or, shall I stick to RTRACE tool directly through pure
Radiance?

And, if I have to stick to using Pure Radiance (RTRACE), is the method
detailed in the attached document (hope, you see that: where Geometry
and Workplane sensors are built in Ecotect and directly exported to
Radiance engine), is it still valid?

Finally, in both cases (using pure Radiance and/or Daysim), shall we
replace the Radiance tool (works as engine) by the latest released
version (i.e. Version 4.2 or recent?) as the one works with
Ecotect-Radiance approach (I'm not sure about Daysim, yet) is old
version (2.0; in think!)?

Really, I am grateful to you for your appreciated help and looking to
hear from you again :slight_smile:

Regards,

Ikrima

As some of you may remember, I am trying to model a set of CFS to
compare their effect on indoor horizontal illuminance of a room.

So far, I have been advised by you for several stages, which really
helped me a lot for better understanding of radiance and how it works.
Now, I have a question about how I use ray-tracing method in radiance?
Is it similar to the way explained through the following attachment?
As here, calculations are run using Radiance engine but Ecotect or
Daysim interface (for geometry modelling and material assignment).
Document:
http://web.mit.edu/sustainabledesignlab/projects/TeachingResources/Gett
ing
StartedwithEcotectRadianceDaysim.pdf

I hope if you can kindly advise me on that asap, please?

Ikrima,

Strictly speaking, Radiance always use ray-tracing. Whenever you call
RPICT, RTRACE or RCONTRIB, there will always be a ray-tracing
simulation performed. However, when you want to perform annual
simulations, you will want to do as few ray-tracing simulations as
possible since they take time.
RTRACE, for example, is a method used to calculate the illuminance or
luminance of a point (sensor) in a static scene. Doing this for a whole
year would require 8760 or more RTRACE calls, which means 8760 or more
ray-tracing simulations, which is slow.

Accordingly, Daysim (which uses the 2-phase method) runs one
ray-tracing simulation that calculates the Daylight Coefficient matrix
(this can be done in pure radiance by using RCONTRIB). This matrix
relates the sensors
(workplane?) in the scene with the sky, mich means that you can modify
the sky and quickly evaluate illuminance in the same points. This
allows performing annual simulations fast (only the sky changes in a
static annual simulation). 3 and 5 phase method are extensions to this
that allow also modifying the CFSs in the scene.

Hope that clarify a little bit.

-----Original Message-----
From: [email protected]
[mailto:[email protected]]
Sent: 10 August 2015 14:20
To: [email protected]
Subject: Radiance-general Digest, Vol 138, Issue 12

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   1. Re: Ray-tracing with Radiance (Germ?n Molina Larrain)

----------------------------------------------------------------------

Message: 1
Date: Mon, 10 Aug 2015 10:19:18 -0300
From: Germ?n Molina Larrain <[email protected]>
To: Radiance general discussion <[email protected]>
Subject: Re: [Radiance-general] Ray-tracing with Radiance
Message-ID:

<CAF-iH4LVHB_V+Vmy-mSiv2EtUE25KDxtTAyJfao5Mi6fzFDU1g@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

Ikrima,

Strictly speaking, Radiance always use ray-tracing. Whenever you call
RPICT, RTRACE or RCONTRIB, there will always be a ray-tracing
simulation performed. However, when you want to perform annual
simulations, you will want to do as few ray-tracing simulations as
possible since they take time.
RTRACE, for example, is a method used to calculate the illuminance or
luminance of a point (sensor) in a static scene. Doing this for a whole
year would require 8760 or more RTRACE calls, which means 8760 or more
ray-tracing simulations, which is slow.

Accordingly, Daysim (which uses the 2-phase method) runs one
ray-tracing simulation that calculates the Daylight Coefficient matrix
(this can be done in pure radiance by using RCONTRIB). This matrix
relates the sensors
(workplane?) in the scene with the sky, mich means that you can modify
the sky and quickly evaluate illuminance in the same points. This
allows performing annual simulations fast (only the sky changes in a
static annual simulation). 3 and 5 phase method are extensions to this
that allow also modifying the CFSs in the scene.

Hope that clarify a little bit.

Best,

Germ?n

2015-08-10 8:51 GMT-03:00 Ikrima Amaireh <[email protected]>:

Hello Robert,
Hello all,

As some of you may remember, I am trying to model a set of CFS to
compare their effect on indoor horizontal illuminance of a room. So
far, I have been advised by you for several stages, which really
helped me a lot for better understanding of radiance and how it works.

Now, I have a question about how I use ray-tracing method in radiance?
Is it similar to the way explained through the following attachment?
As here, calculations are run using Radiance engine but Ecotect or
Daysim interface (for geometry modelling and material assignment).

Document:
http://web.mit.edu/sustainabledesignlab/projects/TeachingResources/Ge
t tingStartedwithEcotectRadianceDaysim.pdf

I hope if you can kindly advise me on that asap, please?

Best regards
Ikrima

-----Original Message-----
From: [email protected] [mailto:
[email protected]]
Sent: 12 July 2015 20:37
To: [email protected]
Subject: Radiance-general Digest, Vol 137, Issue 12

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    1. Git for Windows and starting tutorials (Ikrima Amaireh)

---------------------------------------------------------------------
-

Message: 1
Date: Sun, 12 Jul 2015 20:36:19 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
         <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] Git for Windows and starting tutorials
Message-ID:
         <
D697763F9F216044A99BC674C00561961358CA9C4C@EXCHANGE1.ad.nottingham.ac.
>

Content-Type: text/plain; charset="us-ascii"

Hi Robert,

Many thanks for your help.

I have installed Git for Windows as you adviced :slight_smile: Now, Before I
start with 3 or 5-phase tutorials, I'm thinking to go through
"radiance tutorial"
(by Axel Jacobs) as a beginner with almost a shallow
knowledge/experience of radiance. So, do recommend this (radiance
tutorial would be enough to start with 3 or 5-phase methods and
understanding of BSDF data approach,
etc) or advice another tutorial/source for better understanding of
radiance basics (using command prompt)?

Many thanks again :slight_smile:

Regards
Ikrima

------------------------------

Message: 2
Date: Fri, 10 Jul 2015 15:52:23 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
         <[email protected]>
Subject: Re: [Radiance-general] Radiance-general Digest, Vol 137,
         Issue 8
Message-ID: <D1C542EA.1AE88%[email protected]>
Content-Type: text/plain; charset="us-ascii"

OK so it sounds like you first tried the Windows installer
(presumably a NREL-provided one such as this:
https://github.com/NREL/Radiance/releases/download/5.0.a.3/radiance-5.
0.a-w in64.exe), and this most likely worked fine, you just had some
issues actually *doing* anything with it. This is normal. =)

I recommend you install Git for windows (https://msysgit.github.io/),
as that will add a little BASH emulator in your Windows system. This
way you can run most of the commands exactly as they appear in most
of the tutorials out there that are written from a UNIX perspective
(as you point out). If you run the "Git BASH shell" you will be able
to try out all the multi-phase methods, use and generate BSDFs, etc.
Once you have Git for Windows installed, head over to Andy McNeil's
tutorials for 3- and 5-phase, fire up the Git BASH shell (it'll be in
the Git program group in the Windows start menu), and get started!

One thing to keep in mind is that when running any commands that
read/write data (e.g. rcontrib), be sure to use ASCII format rather
than float. Windows has issues with float data (among many other
things).

Good luck!

- Rob

On 7/10/15, 8:08 AM, "Ikrima Amaireh" <[email protected]> wrote:

Hi Robert,

My PC is running on Windows 7 Enterprise.
Initially, I installed Radiance for Window using its installer but I
found that most of the tutorials are provided for pc with Linux
and/or Linux-like operating systems; So I had to install try learnix
(that did not work) and Ubuntu (also did not work)!
Finally, I tried to use Cygwin to run Radiance on Window OS. I could
install Cygwin (works fine), Xming (not sure if working) and
Radiance (not all its programs are working!).

I'm a bit confused as I'm not sure if running Radiance on windows
using Cygwin will be enough for carrying my work. For example, can I
work out phases methods and generate BSDF data?

I wish if you can help me to do that.

Many thanks
ikrima

------------------------------

Message: 3
Date: Thu, 9 Jul 2015 16:44:49 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
       <[email protected]>
Subject: Re: [Radiance-general] Could not install Radiance!!!
Message-ID: <D1C400AC.1ADAC%[email protected]>
Content-Type: text/plain; charset="us-ascii"

Hi Ikrima,

We'll need a bit more info, here. What OS are you on? How are you
attempting to install it (using an installer, compiling from source,
or what)? What happens when you try??

On 7/9/15, 10:38 AM, "Ikrima Amaireh" <[email protected]> wrote:

Hi all,

After one a few weeks of trying, I could not manage to install
radiance properly. I am almost disappointed! Please any help?

Regards
Ikrima

This message and any attachment are intended solely for the
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------------------------------

Message: 3
Date: Fri, 10 Jul 2015 17:34:30 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
         <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] Modelling CFS
Message-ID:
         <
D697763F9F216044A99BC674C00561961358CA9BAF@EXCHANGE1.ad.nottingham.ac.
>

Content-Type: text/plain; charset="us-ascii"

Hi all,

Thanks Robert and Larrain for your detailed replies, that helped me a
lot.

I would summarise here what I got form your appreciated replies, as
following:
- Radiance is convenient and best of tools to model daylighting due
to its ray-tracing method.
- 3 or 5-phases methods are used to facilitate the calculations.
- Generating BSDF data is also used to facilitate these calculations
but it is limited to Klems resolution of some CFS.

Initially, I'm not planning to do annual calculations. It's just for
specific hours of the day and the target is to produce a illuminance
levels for indoor grid under different CFSs. Hence, according to my
understanding from Larrain words, I can use either 2-phase or
Ray-tracing methods. My question is how can I draw/define the CFS
geometry and Space for these calculations? Is it similar to the way
use in Ecotect/Radiance calculations?

Regards
Ikrima

  -----Original Message-----
From: [email protected] [mailto:
[email protected]]
Sent: 09 July 2015 19:56
To: [email protected]
Subject: Radiance-general Digest, Vol 137, Issue 8

Send Radiance-general mailing list submissions to
         [email protected]

To subscribe or unsubscribe via the World Wide Web, visit

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You can reach the person managing the list at
         [email protected]

When replying, please edit your Subject line so it is more specific
than
"Re: Contents of Radiance-general digest..."

Today's Topics:

    1. CFS with Radiance (Ikrima Amaireh)
    2. Could not install Radiance!!! (Ikrima Amaireh)
    3. Re: Could not install Radiance!!! (Guglielmetti, Robert)
    4. Re: CFS with Radiance (Guglielmetti, Robert)
    5. Re: CFS with Radiance (Germ?n Molina Larrain)

---------------------------------------------------------------------
-

Message: 1
Date: Thu, 9 Jul 2015 17:26:29 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
         <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] CFS with Radiance
Message-ID:
         <
D697763F9F216044A99BC674C00561961358CA9710@EXCHANGE1.ad.nottingham.ac.
>

Content-Type: text/plain; charset="us-ascii"

Hi G. Larrain,

Thanks for your detailed clarification (below).

I wonder if you kindly can help me toward better understanding and
answering the following:

We agreed that for daylight modelling of spaces with CFS, Radiance is
a suitable tool as it applies ray-tracing method. And for annual
and/or climate-based daylight calculations, as calculation time
becomes a critical factor, using BSDF data for CFS is highly
recommended to tackle the task with radiance (using phases methods).
However:

- if someone needs to perform daylight calculations for given space
with different CFS (different cases for comparison purposes) to get
illumination levels for horizontal grid points (and not pictures nor
scenes), is Radiance still the most convenient option?
- is it still needed to use any of the phase methods (2, 3 or 5)?
- most importantly, is it still needed to get BSDF data for CFS or
just can model the detailed CFS in Radiance (and, if yes, how?)

Many thanks for your kind help :slight_smile:

Regards
Ikrima

"Ikrima,

I am going to try to build the puzzle of CFS, Phases, BSDF and
calculations.... at least the way I understand it.

*CFS* are those systems that, via interreflection or other light
transport phenomena, redirect light (or solar radiation). Thus, in
order to get a reliable result you will have to consider all the
phenomena involved.
Then, *common
simple performance indexes*, such as the miss-used Shading
Coefficient and the Aperture Percentage, *always loose a lot of
information, trying to reduce all the complex behavior of a CFS to
one single number*. We all know that venetian blinds are more
"transparent" from certain viewing directions than from others, but
these performance indexes do not tell you that.

Now... Radiance can certainly perform calculations of spaces with CFS
using its "common" Ray-tracing. However, this may be slow for some
purposes (i.e.
annual simulations and climate-based daylight modelling), and *this
is why 2, 3 and 5 phase methods have been developed*. The *BSDF*
representation, I would say, goes in the same direction... It allow
summarizing all the bounces, reflections, refractions, etc. that
occure withing the CFS in a single matrix or tensor.* By using
BSDFs*, Radiance itself and other tools (i.e. EnergyPlus) can treat
CFS as blackboxes, avoiding all the opcits within the system. A BSDF
that uses the Klems Full representation has
21,045 numbers (instead of one, such as the Shading Coefficient).

Being said all that, I would not trust a calculation method unless it
can actually deal with the optics of a CFS that is drawn and/or it
can use BSDF (or similar) information.

Lets remember that a perforated screen, a venetian blind, a light
diffusing device can all have a Shading Coefficient of 50%, but all
of them will behave very differently. I made some presentations about
this on my previous work (we sold complex Shading Devices), trying to
promote the use of BSDF in EnergyPlus calculations... the differences
(in solar heat gains) were more than considerable.

I hope that someone else gives us his/her perspective on this topic...
there are a lot of concepts that I might be misunderstanding.

Best!"

This message and any attachment are intended solely for the addressee
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Please do not use, copy or disclose the information contained in this
message or in any attachment. Any views or opinions expressed by the
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University of Nottingham.

This message has been checked for viruses but the contents of an
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------------------------------

Message: 2
Date: Thu, 9 Jul 2015 17:38:41 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
         <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] Could not install Radiance!!!
Message-ID:
         <
D697763F9F216044A99BC674C00561961358CA9719@EXCHANGE1.ad.nottingham.ac.
>

Content-Type: text/plain; charset="us-ascii"

Hi all,

After one a few weeks of trying, I could not manage to install
radiance properly. I am almost disappointed! Please any help?

Regards
Ikrima

This message and any attachment are intended solely for the addressee
and may contain confidential information. If you have received this
message in error, please send it back to me, and immediately delete it.

Please do not use, copy or disclose the information contained in this
message or in any attachment. Any views or opinions expressed by the
author of this email do not necessarily reflect the views of the
University of Nottingham.

This message has been checked for viruses but the contents of an
attachment may still contain software viruses which could damage your
computer system, you are advised to perform your own checks. Email
communications with the University of Nottingham may be monitored as
permitted by UK legislation.

------------------------------

Message: 3
Date: Thu, 9 Jul 2015 16:44:49 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
         <[email protected]>
Subject: Re: [Radiance-general] Could not install Radiance!!!
Message-ID: <D1C400AC.1ADAC%[email protected]>
Content-Type: text/plain; charset="us-ascii"

Hi Ikrima,

We'll need a bit more info, here. What OS are you on? How are you
attempting to install it (using an installer, compiling from source,
or what)? What happens when you try??

On 7/9/15, 10:38 AM, "Ikrima Amaireh" <[email protected]> wrote:

Hi all,

After one a few weeks of trying, I could not manage to install
radiance properly. I am almost disappointed! Please any help?

Regards
Ikrima

This message and any attachment are intended solely for the
addressee and may contain confidential information. If you have
received this message in error, please send it back to me, and

immediately delete it.

Please do not use, copy or disclose the information contained in
this message or in any attachment. Any views or opinions expressed
by the author of this email do not necessarily reflect the views of
the University of Nottingham.

This message has been checked for viruses but the contents of an
attachment may still contain software viruses which could damage
your computer system, you are advised to perform your own checks.
Email communications with the University of Nottingham may be
monitored as permitted by UK legislation.

_______________________________________________
Radiance-general mailing list
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http://www.radiance-online.org/mailman/listinfo/radiance-general

------------------------------

Message: 4
Date: Thu, 9 Jul 2015 17:29:39 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
         <[email protected]>
Subject: Re: [Radiance-general] CFS with Radiance
Message-ID: <D1C40477.1ADCA%[email protected]>
Content-Type: text/plain; charset="us-ascii"

Some very quick replies and clarifications within:

On 7/9/15, 10:26 AM, "Ikrima Amaireh" <[email protected]> wrote:

Hi G. Larrain,

Thanks for your detailed clarification (below).

I wonder if you kindly can help me toward better understanding and
answering the following:

We agreed that for daylight modelling of spaces with CFS, Radiance
is a suitable tool as it applies ray-tracing method. And for annual
and/or climate-based daylight calculations, as calculation time
becomes a critical factor, using BSDF data for CFS is highly
recommended to tackle the task with radiance (using phases methods).

However:

BSDF data in an annual simulation context is generally limited to
Klems basis BSDF data, which may not be high enough resolution for
some CFS. And the 5-phase method, which can circumvent this, is not
necessarily "quick".
This is all still very much a quandary and the newest daylight
metrics have added confusion to all of this, IMO.

- if someone needs to perform daylight calculations for given space
with different CFS (different cases for comparison purposes) to get
illumination levels for horizontal grid points (and not pictures nor
scenes), is Radiance still the most convenient option?

Absolutely. The lack of an image-as-output requirement does not
change the fact that ray tracing is a good/convenient algorithm
option for daylight simulation problems, especially when dealing with
diffusing media and CFS in general. BSDFs allow you to do lots of
"what-ifs", relatively quickly, but are beholden to the limitations
of the resolution of the BSDF.

- is it still needed to use any of the phase methods (2, 3 or 5)?

Is what still needed? BSDF data? Ray tracing? I don't know of other
lighting simulation tools that can employ the multiphase methods. I
would say BSDF data is optional for 2-phase, required for 3-phase,
and optional for 5-phase.

- most importantly, is it still needed to get BSDF data for CFS or
just can model the detailed CFS in Radiance (and, if yes, how?)

Again I'm confused as to what "it" is. A couple of approaches are
available to you in general. If you have a geometric model of the CFS
you can use Radiance (genBSDF) to make a BSDF of the CFS and use that
in a 3- or 5-phase context. However in an annual/climate-based
simulation context, you will be stuck with a Klems basis BSDF and that
will not be very good resolution for a lot of CFS; here you may want
to use the 5-phase method and stick the actual CFS geometry in the
building model.

Some things to consider here are the photon map, now a part of
Radiance proper, or using the 2-phase method where appropriate. By
2-phase method I mean generating a daylight matrix for your
calculation points (or view), and modeling the window material as-is.
If the "CFS" is a shade cloth, you can approximate that with a
Radiance "trans". Same for translucent panels.
With this single daylight matrix, you can throw a vector of sky
matrices at it and get an annual climate-based result very quickly.
Problem is, we want to do stuff to the windows, sometimes at the time
step level, so:

Blinds and compact daylight redirection devices (e.g. Lightlouver)
are best represented as BSDF, and if most of the redirected flux is
headed up and away from the points of interest, a Klems basis BSDF is
good enough IMO. In these cases you could use the 3-phase method.
Problem is when you have a BSDF for blinds, and you also want to
simulate the blinds-up condition (i.e. clear, specularly transmitting
glass). Using a Klems basis BSDF for this is sub-optimal. You end up
needing to do two annual simulations, one as 2-phase for the clear
glass scenario, and again as a 3-phase (with a blinds BSDF for the
transmission
matrix) for the blinds down condition. If you have a lot of different
window groups, your simulation space can get large in a hurry. But
it's still do-able and you can get results that tell a story you
simply couldn't tell 5 years ago, informing the newest daylight
metrics as well.

------------------------------

Message: 5
Date: Thu, 9 Jul 2015 15:56:11 -0300
From: Germ?n Molina Larrain <[email protected]>
To: Radiance general discussion
<[email protected]>
Subject: Re: [Radiance-general] CFS with Radiance
Message-ID:
         <CAF-iH4LSr=y12F1khTrHh6hnf-kS=EmaFuo8uWKvHqMs=
[email protected]>
Content-Type: text/plain; charset="utf-8"

I must say that I agree with Rob, however, a short answer that might
help.

For evaluating illuminance levels in a space with different CFS you,
strictly speaking, DO NOT HAVE TO do anything. You may choose between
different methods that have some pros and cons.

*ray-tracing*

    - Requires ray-tracing for each time-step and each system, which
is slow
    (*four systems simulated annualy in an hourly basis --> 4*8760 =
35,040
    simulations*.)
    - As accurate as it gets, if options are defined correctly.

*2 phase method*

    - Do not need the BSDF
    - Requires ray-tracing for each CFS (*4 systems --> 4 ray-tracing
    simulations*)
    - After ray-tracing, annual simulation is fast.

*3-phase method:*

    - Requires BSDF data in KLEMS basis, which may be slow to compute,
    unless it can be exported from WINDOW, for example, or such data has
    already been calculated (the idea is to make a database, I think).
    - Does not really work well for specular systems (Klems patches
are too
    big)
    - Requires 2 ray-tracing runs, always (*4 systems --> 2 ray-tracing
    simulations*)
    - After ray-tracing and BSDF calculation, annual simulation is
fast

*5-phase method:*

    - Requires BSDF data in KLEMS basis AND/OR Tensor tree format,
which
    may be slow to compute, unless it can be exported from WINDOW, for
example,
    or such data has already been calculated (the idea is to make a
database, I
    think).
    - Works well for specular systems
    - Requires 4 ray-tracing runs + 1 for each system, always (*4
systems
    --> 4+1 = 5 ray-tracing simulations*)
    - Hard to code...?
    - After ray-tracing and BSDF calculation, annual simulation is
fast

I would not say there is a recipe. If you have to choose between 1 or
2 CFSs, maybe it is faster to just draw them and use the 2 phase
method (or ray-tracing if an annual simulaton is not required). On
the contrary, if you are going to test 10 different CFSs, 3 and 5
phases may make sense, since you reduce the expensive ray-tracing
calculations... However, this will also depend on weather you have
the BSDF data AND/OR if it makes sense to calculate it and store it
AND/OR if you intend to simulate a dynamically controlled CFS.

Best!

2015-07-09 14:29 GMT-03:00 Guglielmetti, Robert <
[email protected]>:

Some very quick replies and clarifications within:

On 7/9/15, 10:26 AM, "Ikrima Amaireh" <[email protected]> wrote:

Hi G. Larrain,

Thanks for your detailed clarification (below).

I wonder if you kindly can help me toward better understanding and
answering the following:

We agreed that for daylight modelling of spaces with CFS, Radiance
is a suitable tool as it applies ray-tracing method. And for
annual and/or climate-based daylight calculations, as calculation
time becomes a critical factor, using BSDF data for CFS is highly
recommended to tackle the task with radiance (using phases methods).

However:

BSDF data in an annual simulation context is generally limited to
Klems basis BSDF data, which may not be high enough resolution for
some CFS. And the 5-phase method, which can circumvent this, is not

necessarily "quick".

This is all still very much a quandary and the newest daylight
metrics have added confusion to all of this, IMO.

- if someone needs to perform daylight calculations for given
space with different CFS (different cases for comparison purposes)
to get illumination levels for horizontal grid points (and not
pictures nor scenes), is Radiance still the most convenient option?

Absolutely. The lack of an image-as-output requirement does not
change the fact that ray tracing is a good/convenient algorithm
option for daylight simulation problems, especially when dealing
with diffusing media and CFS in general. BSDFs allow you to do lots
of "what-ifs", relatively quickly, but are beholden to the
limitations of the

resolution of the BSDF.

- is it still needed to use any of the phase methods (2, 3 or 5)?

Is what still needed? BSDF data? Ray tracing? I don't know of other
lighting simulation tools that can employ the multiphase methods. I
would say BSDF data is optional for 2-phase, required for 3-phase,
and optional for 5-phase.

- most importantly, is it still needed to get BSDF data for CFS or
just can model the detailed CFS in Radiance (and, if yes, how?)

Again I'm confused as to what "it" is. A couple of approaches are
available to you in general. If you have a geometric model of the
CFS you can use Radiance (genBSDF) to make a BSDF of the CFS and
use that in a 3- or 5-phase context. However in an
annual/climate-based simulation context, you will be stuck with a
Klems basis BSDF and that will not be very good resolution for a
lot of CFS; here you may want to use the 5-phase method and stick
the actual CFS geometry in the

building model.

Some things to consider here are the photon map, now a part of
Radiance proper, or using the 2-phase method where appropriate. By
2-phase method I mean generating a daylight matrix for your
calculation points (or view), and modeling the window material as-is.
If the "CFS" is a shade cloth, you can approximate that with a
Radiance

"trans". Same for translucent panels.

With this single daylight matrix, you can throw a vector of sky
matrices at it and get an annual climate-based result very quickly.
Problem is, we want to do stuff to the windows, sometimes at the
time

step level, so:

Blinds and compact daylight redirection devices (e.g. Lightlouver)
are best represented as BSDF, and if most of the redirected flux is
headed up and away from the points of interest, a Klems basis BSDF
is good enough IMO. In these cases you could use the 3-phase method.
Problem is when you have a BSDF for blinds, and you also want to
simulate the blinds-up condition (i.e. clear, specularly
transmitting glass). Using a Klems basis BSDF for this is
sub-optimal. You end up needing to do two annual simulations, one
as 2-phase for the clear glass scenario, and again as a 3-phase
(with a blinds BSDF for the transmission
matrix) for the blinds down condition. If you have a lot of
different window groups, your simulation space can get large in a
hurry. But it's still do-able and you can get results that tell a
story you simply couldn't tell 5 years ago, informing the newest
daylight metrics

as well.

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Dear Alstan,

Yes, you actually did :slight_smile:

What exactly I want to do is: modelling different CFS to assess their effect on indoor illuminance (Workplane). So, Daysim (with its current old version Radiance binaries) can do that; isn't it? At the same time, one can still say that simulations are based on the powerful Radiance tools, does that sound right, too?

So far, I don't think I still need to use BSDF as there is no need for 3- nor 5-phase methods for such level of work!

Can you please correct me if there is something wrong with my understanding/assumptions?

Best regards
Ikrima

···

-----Original Message-----
From: [email protected] [mailto:[email protected]]
Sent: 11 August 2015 17:00
To: [email protected]
Subject: Radiance-general Digest, Vol 138, Issue 22

Send Radiance-general mailing list submissions to
        [email protected]

To subscribe or unsubscribe via the World Wide Web, visit
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Today's Topics:

   1. Re: rcontrib with 2-phase method? (J. Alstan Jakubiec)

----------------------------------------------------------------------

Message: 1
Date: Tue, 11 Aug 2015 23:38:14 +0800
From: "J. Alstan Jakubiec" <[email protected]>
To: [email protected]
Cc: [email protected]
Subject: Re: [Radiance-general] rcontrib with 2-phase method?
Message-ID: <[email protected]>
Content-Type: text/plain; charset="windows-1252"; Format="flowed"

Dear Ikrima,

Daysim comes with its own special version of the Radiance binaries that can be downloaded at the Daysim website <http://daysim.ning.com/>. These get stored in c:\DAYSIM\bin\ after installation on Windows.
Unfortunately the binaries are based on an older Radiance version, so you miss some options like using BSDF data. Still, Daysim is perfectly serviceable for most cases. I hope I understood your question.

Best,
Alstan

On 8/11/2015 11:09 PM, Guglielmetti, Robert wrote:

I really have no experience with Daysim at this point so I really am
not the best person to answer this one, sorry. In a general sense,
with respect to Daysim and Radiance you'd use one or the other, not
both. The Radiance daylight coefficient method (i.e. using rcontrib
and other tools in Radiance to do a 2-phase annual simulation) *is*
basically the same thing as Daysim. Hope this helps but it probably
doesn't. =/

On 8/11/15, 4:54 AM, "Ikrima Amaireh" <[email protected]> wrote:

Dear Robert,

Thanks for making clear that using rcontrib and using 3/5 phase
methods need a recent version of radiance. does that apply to using
2-phse
(Daysim) or one can still use old versions of radiance (as I have a
problem yet with installing recent versions of radiance and link it
with Daysim tool)?

Many thanks for you in advance:

Regards,
ikriam

------------------------------

Message: 2
Date: Mon, 10 Aug 2015 17:03:49 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
        <[email protected]>
Subject: Re: [Radiance-general] Ray-tracing with Radiance
Message-ID: <D1EE1EEF.1B923%[email protected]>
Content-Type: text/plain; charset="us-ascii"

There is a daysim-specific mailing list that may be useful for some
of your questions:

http://www.radiance-online.org/community/mailing-lists/subscribe/radi
ance-
d
aysim

I can tell you that if you're planning to use rcontrib and do 3- or
5-phase type stuff, you definitely should be using a recent version
of Radiance. Either build from latest source, or use one of the NREL
pre-built packages (I recommend v5):

https://github.com/NREL/Radiance/releases/tag/5.0.a.3

On 8/10/15, 9:14 AM, "Ikrima Amaireh" <[email protected]> wrote:

Dear Germ?n,

Many thanks for you. I agree with you totally that all Radiance
works need to apply ray-tracing approach as the core principle of it.
However, what I meant by using ray-tracing in radiance, was the
using of RTRACE directly through stand-alone radiance tool (as you
kindly mentioned).

As you clarified, Daysim uses 2-phase method to do annual simulation
(2nd
phase) fast, based on pre-calculated Daylight Coefficient Matrix
(1st phase). Now, if I need to produce the illuminance levels
(produced by specific CFS) at the Workplane under static scene, can
I still use Daysim for that? Or, shall I stick to RTRACE tool
directly through pure Radiance?

And, if I have to stick to using Pure Radiance (RTRACE), is the
method detailed in the attached document (hope, you see that: where
Geometry and Workplane sensors are built in Ecotect and directly
exported to Radiance engine), is it still valid?

Finally, in both cases (using pure Radiance and/or Daysim), shall we
replace the Radiance tool (works as engine) by the latest released
version (i.e. Version 4.2 or recent?) as the one works with
Ecotect-Radiance approach (I'm not sure about Daysim, yet) is old
version (2.0; in think!)?

Really, I am grateful to you for your appreciated help and looking
to hear from you again :slight_smile:

Regards,

Ikrima

As some of you may remember, I am trying to model a set of CFS to
compare their effect on indoor horizontal illuminance of a room.

So far, I have been advised by you for several stages, which really
helped me a lot for better understanding of radiance and how it works.
Now, I have a question about how I use ray-tracing method in radiance?
Is it similar to the way explained through the following attachment?
As here, calculations are run using Radiance engine but Ecotect or
Daysim interface (for geometry modelling and material assignment).
Document:
http://web.mit.edu/sustainabledesignlab/projects/TeachingResources/G
ett
ing
StartedwithEcotectRadianceDaysim.pdf

I hope if you can kindly advise me on that asap, please?

Ikrima,

Strictly speaking, Radiance always use ray-tracing. Whenever you
call RPICT, RTRACE or RCONTRIB, there will always be a ray-tracing
simulation performed. However, when you want to perform annual
simulations, you will want to do as few ray-tracing simulations as
possible since they take time.
RTRACE, for example, is a method used to calculate the illuminance
or luminance of a point (sensor) in a static scene. Doing this for a
whole year would require 8760 or more RTRACE calls, which means 8760
or more ray-tracing simulations, which is slow.

Accordingly, Daysim (which uses the 2-phase method) runs one
ray-tracing simulation that calculates the Daylight Coefficient
matrix (this can be done in pure radiance by using RCONTRIB). This
matrix relates the sensors
(workplane?) in the scene with the sky, mich means that you can
modify the sky and quickly evaluate illuminance in the same points.
This allows performing annual simulations fast (only the sky changes
in a static annual simulation). 3 and 5 phase method are extensions
to this that allow also modifying the CFSs in the scene.

Hope that clarify a little bit.

-----Original Message-----
From: [email protected]
[mailto:[email protected]]
Sent: 10 August 2015 14:20
To: [email protected]
Subject: Radiance-general Digest, Vol 138, Issue 12

Send Radiance-general mailing list submissions to
        [email protected]

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Today's Topics:

   1. Re: Ray-tracing with Radiance (Germ?n Molina Larrain)

--------------------------------------------------------------------
--

Message: 1
Date: Mon, 10 Aug 2015 10:19:18 -0300
From: Germ?n Molina Larrain <[email protected]>
To: Radiance general discussion
<[email protected]>
Subject: Re: [Radiance-general] Ray-tracing with Radiance
Message-ID:

<CAF-iH4LVHB_V+Vmy-mSiv2EtUE25KDxtTAyJfao5Mi6fzFDU1g@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

Ikrima,

Strictly speaking, Radiance always use ray-tracing. Whenever you
call RPICT, RTRACE or RCONTRIB, there will always be a ray-tracing
simulation performed. However, when you want to perform annual
simulations, you will want to do as few ray-tracing simulations as
possible since they take time.
RTRACE, for example, is a method used to calculate the illuminance
or luminance of a point (sensor) in a static scene. Doing this for a
whole year would require 8760 or more RTRACE calls, which means 8760
or more ray-tracing simulations, which is slow.

Accordingly, Daysim (which uses the 2-phase method) runs one
ray-tracing simulation that calculates the Daylight Coefficient
matrix (this can be done in pure radiance by using RCONTRIB). This
matrix relates the sensors
(workplane?) in the scene with the sky, mich means that you can
modify the sky and quickly evaluate illuminance in the same points.
This allows performing annual simulations fast (only the sky changes
in a static annual simulation). 3 and 5 phase method are extensions
to this that allow also modifying the CFSs in the scene.

Hope that clarify a little bit.

Best,

Germ?n

2015-08-10 8:51 GMT-03:00 Ikrima Amaireh <[email protected]>:

Hello Robert,
Hello all,

As some of you may remember, I am trying to model a set of CFS to
compare their effect on indoor horizontal illuminance of a room. So
far, I have been advised by you for several stages, which really
helped me a lot for better understanding of radiance and how it works.

Now, I have a question about how I use ray-tracing method in radiance?
Is it similar to the way explained through the following attachment?
As here, calculations are run using Radiance engine but Ecotect or
Daysim interface (for geometry modelling and material assignment).

Document:
http://web.mit.edu/sustainabledesignlab/projects/TeachingResources/
Ge t tingStartedwithEcotectRadianceDaysim.pdf

I hope if you can kindly advise me on that asap, please?

Best regards
Ikrima

-----Original Message-----
From: [email protected] [mailto:
[email protected]]
Sent: 12 July 2015 20:37
To: [email protected]
Subject: Radiance-general Digest, Vol 137, Issue 12

Send Radiance-general mailing list submissions to
         [email protected]

To subscribe or unsubscribe via the World Wide Web, visit

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         [email protected]

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Today's Topics:

    1. Git for Windows and starting tutorials (Ikrima Amaireh)

-------------------------------------------------------------------
--
-

Message: 1
Date: Sun, 12 Jul 2015 20:36:19 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
         <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] Git for Windows and starting tutorials
Message-ID:
         <
D697763F9F216044A99BC674C00561961358CA9C4C@EXCHANGE1.ad.nottingham.ac.
>

Content-Type: text/plain; charset="us-ascii"

Hi Robert,

Many thanks for your help.

I have installed Git for Windows as you adviced :slight_smile: Now, Before I
start with 3 or 5-phase tutorials, I'm thinking to go through
"radiance tutorial"
(by Axel Jacobs) as a beginner with almost a shallow
knowledge/experience of radiance. So, do recommend this (radiance
tutorial would be enough to start with 3 or 5-phase methods and
understanding of BSDF data approach,
etc) or advice another tutorial/source for better understanding of
radiance basics (using command prompt)?

Many thanks again :slight_smile:

Regards
Ikrima

------------------------------

Message: 2
Date: Fri, 10 Jul 2015 15:52:23 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
         <[email protected]>
Subject: Re: [Radiance-general] Radiance-general Digest, Vol 137,
         Issue 8
Message-ID: <D1C542EA.1AE88%[email protected]>
Content-Type: text/plain; charset="us-ascii"

OK so it sounds like you first tried the Windows installer
(presumably a NREL-provided one such as this:
https://github.com/NREL/Radiance/releases/download/5.0.a.3/radiance-5.
0.a-w in64.exe), and this most likely worked fine, you just had
some issues actually *doing* anything with it. This is normal. =)

I recommend you install Git for windows
(https://msysgit.github.io/), as that will add a little BASH
emulator in your Windows system. This way you can run most of the
commands exactly as they appear in most of the tutorials out there
that are written from a UNIX perspective (as you point out). If you
run the "Git BASH shell" you will be able to try out all the multi-phase methods, use and generate BSDFs, etc.
Once you have Git for Windows installed, head over to Andy McNeil's
tutorials for 3- and 5-phase, fire up the Git BASH shell (it'll be
in the Git program group in the Windows start menu), and get started!

One thing to keep in mind is that when running any commands that
read/write data (e.g. rcontrib), be sure to use ASCII format rather
than float. Windows has issues with float data (among many other
things).

Good luck!

- Rob

On 7/10/15, 8:08 AM, "Ikrima Amaireh" <[email protected]> wrote:

Hi Robert,

My PC is running on Windows 7 Enterprise.
Initially, I installed Radiance for Window using its installer but
I found that most of the tutorials are provided for pc with Linux
and/or Linux-like operating systems; So I had to install try
learnix (that did not work) and Ubuntu (also did not work)!
Finally, I tried to use Cygwin to run Radiance on Window OS. I
could install Cygwin (works fine), Xming (not sure if working) and
Radiance (not all its programs are working!).

I'm a bit confused as I'm not sure if running Radiance on windows
using Cygwin will be enough for carrying my work. For example, can
I work out phases methods and generate BSDF data?

I wish if you can help me to do that.

Many thanks
ikrima

------------------------------

Message: 3
Date: Thu, 9 Jul 2015 16:44:49 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
       <[email protected]>
Subject: Re: [Radiance-general] Could not install Radiance!!!
Message-ID: <D1C400AC.1ADAC%[email protected]>
Content-Type: text/plain; charset="us-ascii"

Hi Ikrima,

We'll need a bit more info, here. What OS are you on? How are you
attempting to install it (using an installer, compiling from
source, or what)? What happens when you try??

On 7/9/15, 10:38 AM, "Ikrima Amaireh" <[email protected]> wrote:

Hi all,

After one a few weeks of trying, I could not manage to install
radiance properly. I am almost disappointed! Please any help?

Regards
Ikrima

This message and any attachment are intended solely for the
addressee and may contain confidential information. If you have
received this message in error, please send it back to me, and

immediately delete it.

Please do not use, copy or disclose the information contained in
this message or in any attachment. Any views or opinions
expressed by the author of this email do not necessarily reflect
the views of the University of Nottingham.

This message has been checked for viruses but the contents of an
attachment may still contain software viruses which could damage
your computer system, you are advised to perform your own checks.
Email communications with the University of Nottingham may be
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------------------------------

Message: 3
Date: Fri, 10 Jul 2015 17:34:30 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
         <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] Modelling CFS
Message-ID:
         <
D697763F9F216044A99BC674C00561961358CA9BAF@EXCHANGE1.ad.nottingham.ac.
>

Content-Type: text/plain; charset="us-ascii"

Hi all,

Thanks Robert and Larrain for your detailed replies, that helped me
a lot.

I would summarise here what I got form your appreciated replies, as
following:
- Radiance is convenient and best of tools to model daylighting due
to its ray-tracing method.
- 3 or 5-phases methods are used to facilitate the calculations.
- Generating BSDF data is also used to facilitate these
calculations but it is limited to Klems resolution of some CFS.

Initially, I'm not planning to do annual calculations. It's just
for specific hours of the day and the target is to produce a
illuminance levels for indoor grid under different CFSs. Hence,
according to my understanding from Larrain words, I can use either
2-phase or Ray-tracing methods. My question is how can I
draw/define the CFS geometry and Space for these calculations? Is
it similar to the way use in Ecotect/Radiance calculations?

Regards
Ikrima

  -----Original Message-----
From: [email protected] [mailto:
[email protected]]
Sent: 09 July 2015 19:56
To: [email protected]
Subject: Radiance-general Digest, Vol 137, Issue 8

Send Radiance-general mailing list submissions to
         [email protected]

To subscribe or unsubscribe via the World Wide Web, visit

http://www.radiance-online.org/mailman/listinfo/radiance-general
or, via email, send a message with subject or body 'help' to
         [email protected]

You can reach the person managing the list at
         [email protected]

When replying, please edit your Subject line so it is more specific
than
"Re: Contents of Radiance-general digest..."

Today's Topics:

    1. CFS with Radiance (Ikrima Amaireh)
    2. Could not install Radiance!!! (Ikrima Amaireh)
    3. Re: Could not install Radiance!!! (Guglielmetti, Robert)
    4. Re: CFS with Radiance (Guglielmetti, Robert)
    5. Re: CFS with Radiance (Germ?n Molina Larrain)

-------------------------------------------------------------------
--
-

Message: 1
Date: Thu, 9 Jul 2015 17:26:29 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
         <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] CFS with Radiance
Message-ID:
         <
D697763F9F216044A99BC674C00561961358CA9710@EXCHANGE1.ad.nottingham.ac.
>

Content-Type: text/plain; charset="us-ascii"

Hi G. Larrain,

Thanks for your detailed clarification (below).

I wonder if you kindly can help me toward better understanding and
answering the following:

We agreed that for daylight modelling of spaces with CFS, Radiance
is a suitable tool as it applies ray-tracing method. And for annual
and/or climate-based daylight calculations, as calculation time
becomes a critical factor, using BSDF data for CFS is highly
recommended to tackle the task with radiance (using phases methods).
However:

- if someone needs to perform daylight calculations for given space
with different CFS (different cases for comparison purposes) to get
illumination levels for horizontal grid points (and not pictures
nor scenes), is Radiance still the most convenient option?
- is it still needed to use any of the phase methods (2, 3 or 5)?
- most importantly, is it still needed to get BSDF data for CFS or
just can model the detailed CFS in Radiance (and, if yes, how?)

Many thanks for your kind help :slight_smile:

Regards
Ikrima

"Ikrima,

I am going to try to build the puzzle of CFS, Phases, BSDF and
calculations.... at least the way I understand it.

*CFS* are those systems that, via interreflection or other light
transport phenomena, redirect light (or solar radiation). Thus, in
order to get a reliable result you will have to consider all the
phenomena involved.
Then, *common
simple performance indexes*, such as the miss-used Shading
Coefficient and the Aperture Percentage, *always loose a lot of
information, trying to reduce all the complex behavior of a CFS to
one single number*. We all know that venetian blinds are more
"transparent" from certain viewing directions than from others,
but these performance indexes do not tell you that.

Now... Radiance can certainly perform calculations of spaces with
CFS using its "common" Ray-tracing. However, this may be slow for
some purposes (i.e.
annual simulations and climate-based daylight modelling), and *this
is why 2, 3 and 5 phase methods have been developed*. The *BSDF*
representation, I would say, goes in the same direction... It allow
summarizing all the bounces, reflections, refractions, etc. that
occure withing the CFS in a single matrix or tensor.* By using
BSDFs*, Radiance itself and other tools (i.e. EnergyPlus) can treat
CFS as blackboxes, avoiding all the opcits within the system. A
BSDF that uses the Klems Full representation has
21,045 numbers (instead of one, such as the Shading Coefficient).

Being said all that, I would not trust a calculation method unless
it can actually deal with the optics of a CFS that is drawn and/or
it can use BSDF (or similar) information.

Lets remember that a perforated screen, a venetian blind, a light
diffusing device can all have a Shading Coefficient of 50%, but all
of them will behave very differently. I made some presentations
about this on my previous work (we sold complex Shading Devices),
trying to promote the use of BSDF in EnergyPlus calculations... the
differences (in solar heat gains) were more than considerable.

I hope that someone else gives us his/her perspective on this topic...
there are a lot of concepts that I might be misunderstanding.

Best!"

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Message: 2
Date: Thu, 9 Jul 2015 17:38:41 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
         <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] Could not install Radiance!!!
Message-ID:
         <
D697763F9F216044A99BC674C00561961358CA9719@EXCHANGE1.ad.nottingham.ac.
>

Content-Type: text/plain; charset="us-ascii"

Hi all,

After one a few weeks of trying, I could not manage to install
radiance properly. I am almost disappointed! Please any help?

Regards
Ikrima

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Message: 3
Date: Thu, 9 Jul 2015 16:44:49 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
         <[email protected]>
Subject: Re: [Radiance-general] Could not install Radiance!!!
Message-ID: <D1C400AC.1ADAC%[email protected]>
Content-Type: text/plain; charset="us-ascii"

Hi Ikrima,

We'll need a bit more info, here. What OS are you on? How are you
attempting to install it (using an installer, compiling from
source, or what)? What happens when you try??

On 7/9/15, 10:38 AM, "Ikrima Amaireh" <[email protected]> wrote:

Hi all,

After one a few weeks of trying, I could not manage to install
radiance properly. I am almost disappointed! Please any help?

Regards
Ikrima

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Message: 4
Date: Thu, 9 Jul 2015 17:29:39 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
         <[email protected]>
Subject: Re: [Radiance-general] CFS with Radiance
Message-ID: <D1C40477.1ADCA%[email protected]>
Content-Type: text/plain; charset="us-ascii"

Some very quick replies and clarifications within:

On 7/9/15, 10:26 AM, "Ikrima Amaireh" <[email protected]> wrote:

Hi G. Larrain,

Thanks for your detailed clarification (below).

I wonder if you kindly can help me toward better understanding and
answering the following:

We agreed that for daylight modelling of spaces with CFS, Radiance
is a suitable tool as it applies ray-tracing method. And for
annual and/or climate-based daylight calculations, as calculation
time becomes a critical factor, using BSDF data for CFS is highly
recommended to tackle the task with radiance (using phases methods).

However:

BSDF data in an annual simulation context is generally limited to
Klems basis BSDF data, which may not be high enough resolution for
some CFS. And the 5-phase method, which can circumvent this, is not
necessarily "quick".
This is all still very much a quandary and the newest daylight
metrics have added confusion to all of this, IMO.

- if someone needs to perform daylight calculations for given
space with different CFS (different cases for comparison purposes)
to get illumination levels for horizontal grid points (and not
pictures nor scenes), is Radiance still the most convenient option?

Absolutely. The lack of an image-as-output requirement does not
change the fact that ray tracing is a good/convenient algorithm
option for daylight simulation problems, especially when dealing
with diffusing media and CFS in general. BSDFs allow you to do
lots of "what-ifs", relatively quickly, but are beholden to the
limitations of the resolution of the BSDF.

- is it still needed to use any of the phase methods (2, 3 or 5)?

Is what still needed? BSDF data? Ray tracing? I don't know of other
lighting simulation tools that can employ the multiphase methods. I
would say BSDF data is optional for 2-phase, required for 3-phase,
and optional for 5-phase.

- most importantly, is it still needed to get BSDF data for CFS or
just can model the detailed CFS in Radiance (and, if yes, how?)

Again I'm confused as to what "it" is. A couple of approaches are
available to you in general. If you have a geometric model of the
CFS you can use Radiance (genBSDF) to make a BSDF of the CFS and
use that in a 3- or 5-phase context. However in an
annual/climate-based simulation context, you will be stuck with a
Klems basis BSDF and that will not be very good resolution for a
lot of CFS; here you may want to use the 5-phase method and stick
the actual CFS geometry in the building model.

Some things to consider here are the photon map, now a part of
Radiance proper, or using the 2-phase method where appropriate. By
2-phase method I mean generating a daylight matrix for your
calculation points (or view), and modeling the window material as-is.
If the "CFS" is a shade cloth, you can approximate that with a
Radiance "trans". Same for translucent panels.
With this single daylight matrix, you can throw a vector of sky
matrices at it and get an annual climate-based result very quickly.
Problem is, we want to do stuff to the windows, sometimes at the
time step level, so:

Blinds and compact daylight redirection devices (e.g. Lightlouver)
are best represented as BSDF, and if most of the redirected flux
is headed up and away from the points of interest, a Klems basis
BSDF is good enough IMO. In these cases you could use the 3-phase method.
Problem is when you have a BSDF for blinds, and you also want to
simulate the blinds-up condition (i.e. clear, specularly
transmitting glass). Using a Klems basis BSDF for this is
sub-optimal. You end up needing to do two annual simulations, one
as 2-phase for the clear glass scenario, and again as a 3-phase
(with a blinds BSDF for the transmission
matrix) for the blinds down condition. If you have a lot of
different window groups, your simulation space can get large in a
hurry. But it's still do-able and you can get results that tell a
story you simply couldn't tell 5 years ago, informing the newest
daylight metrics as well.

------------------------------

Message: 5
Date: Thu, 9 Jul 2015 15:56:11 -0300
From: Germ?n Molina Larrain <[email protected]>
To: Radiance general discussion
<[email protected]>
Subject: Re: [Radiance-general] CFS with Radiance
Message-ID:
         <CAF-iH4LSr=y12F1khTrHh6hnf-kS=EmaFuo8uWKvHqMs=
[email protected]>
Content-Type: text/plain; charset="utf-8"

I must say that I agree with Rob, however, a short answer that
might help.

For evaluating illuminance levels in a space with different CFS
you, strictly speaking, DO NOT HAVE TO do anything. You may choose
between different methods that have some pros and cons.

*ray-tracing*

    - Requires ray-tracing for each time-step and each system,
which is slow
    (*four systems simulated annualy in an hourly basis --> 4*8760

35,040
    simulations*.)
    - As accurate as it gets, if options are defined correctly.

*2 phase method*

    - Do not need the BSDF
    - Requires ray-tracing for each CFS (*4 systems --> 4 ray-tracing
    simulations*)
    - After ray-tracing, annual simulation is fast.

*3-phase method:*

    - Requires BSDF data in KLEMS basis, which may be slow to compute,
    unless it can be exported from WINDOW, for example, or such data has
    already been calculated (the idea is to make a database, I think).
    - Does not really work well for specular systems (Klems patches
are too
    big)
    - Requires 2 ray-tracing runs, always (*4 systems --> 2 ray-tracing
    simulations*)
    - After ray-tracing and BSDF calculation, annual simulation is
fast

*5-phase method:*

    - Requires BSDF data in KLEMS basis AND/OR Tensor tree format,
which
    may be slow to compute, unless it can be exported from WINDOW,
for example,
    or such data has already been calculated (the idea is to make a
database, I
    think).
    - Works well for specular systems
    - Requires 4 ray-tracing runs + 1 for each system, always (*4
systems
    --> 4+1 = 5 ray-tracing simulations*)
    - Hard to code...?
    - After ray-tracing and BSDF calculation, annual simulation is
fast

I would not say there is a recipe. If you have to choose between 1
or
2 CFSs, maybe it is faster to just draw them and use the 2 phase
method (or ray-tracing if an annual simulaton is not required). On
the contrary, if you are going to test 10 different CFSs, 3 and 5
phases may make sense, since you reduce the expensive ray-tracing
calculations... However, this will also depend on weather you have
the BSDF data AND/OR if it makes sense to calculate it and store it
AND/OR if you intend to simulate a dynamically controlled CFS.

Best!

2015-07-09 14:29 GMT-03:00 Guglielmetti, Robert <
[email protected]>:

Some very quick replies and clarifications within:

On 7/9/15, 10:26 AM, "Ikrima Amaireh" <[email protected]> wrote:

Hi G. Larrain,

Thanks for your detailed clarification (below).

I wonder if you kindly can help me toward better understanding
and answering the following:

We agreed that for daylight modelling of spaces with CFS,
Radiance is a suitable tool as it applies ray-tracing method. And
for annual and/or climate-based daylight calculations, as
calculation time becomes a critical factor, using BSDF data for
CFS is highly recommended to tackle the task with radiance (using phases methods).

However:

BSDF data in an annual simulation context is generally limited to
Klems basis BSDF data, which may not be high enough resolution for
some CFS. And the 5-phase method, which can circumvent this, is
not

necessarily "quick".

This is all still very much a quandary and the newest daylight
metrics have added confusion to all of this, IMO.

- if someone needs to perform daylight calculations for given
space with different CFS (different cases for comparison
purposes) to get illumination levels for horizontal grid points
(and not pictures nor scenes), is Radiance still the most convenient option?

Absolutely. The lack of an image-as-output requirement does not
change the fact that ray tracing is a good/convenient algorithm
option for daylight simulation problems, especially when dealing
with diffusing media and CFS in general. BSDFs allow you to do
lots of "what-ifs", relatively quickly, but are beholden to the
limitations of the

resolution of the BSDF.

- is it still needed to use any of the phase methods (2, 3 or 5)?

Is what still needed? BSDF data? Ray tracing? I don't know of
other lighting simulation tools that can employ the multiphase
methods. I would say BSDF data is optional for 2-phase, required
for 3-phase, and optional for 5-phase.

- most importantly, is it still needed to get BSDF data for CFS
or just can model the detailed CFS in Radiance (and, if yes,
how?)

Again I'm confused as to what "it" is. A couple of approaches are
available to you in general. If you have a geometric model of the
CFS you can use Radiance (genBSDF) to make a BSDF of the CFS and
use that in a 3- or 5-phase context. However in an
annual/climate-based simulation context, you will be stuck with a
Klems basis BSDF and that will not be very good resolution for a
lot of CFS; here you may want to use the 5-phase method and stick
the actual CFS geometry in the

building model.

Some things to consider here are the photon map, now a part of
Radiance proper, or using the 2-phase method where appropriate. By
2-phase method I mean generating a daylight matrix for your
calculation points (or view), and modeling the window material as-is.
If the "CFS" is a shade cloth, you can approximate that with a
Radiance

"trans". Same for translucent panels.

With this single daylight matrix, you can throw a vector of sky
matrices at it and get an annual climate-based result very quickly.
Problem is, we want to do stuff to the windows, sometimes at the
time

step level, so:

Blinds and compact daylight redirection devices (e.g. Lightlouver)
are best represented as BSDF, and if most of the redirected flux
is headed up and away from the points of interest, a Klems basis
BSDF is good enough IMO. In these cases you could use the 3-phase method.
Problem is when you have a BSDF for blinds, and you also want to
simulate the blinds-up condition (i.e. clear, specularly
transmitting glass). Using a Klems basis BSDF for this is
sub-optimal. You end up needing to do two annual simulations, one
as 2-phase for the clear glass scenario, and again as a 3-phase
(with a blinds BSDF for the transmission
matrix) for the blinds down condition. If you have a lot of
different window groups, your simulation space can get large in a
hurry. But it's still do-able and you can get results that tell a
story you simply couldn't tell 5 years ago, informing the newest
daylight metrics

as well.

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Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general

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Dear Ikrima,

Yes, I think that is a fair series statements, and it sounds right. You may want to read the Daysim paper in order to understand the methods a bit more,

    Reinhart, Christoph F., and Oliver Walkenhorst. "Validation of
    dynamic RADIANCE-based daylight simulations for a test office with
    external blinds." /Energy and Buildings/ 33.7 (2001): 683-697.

Best,
Alstan

···

On 8/12/2015 12:21 AM, Ikrima Amaireh wrote:

Dear Alstan,

Yes, you actually did :slight_smile:

What exactly I want to do is: modelling different CFS to assess their effect on indoor illuminance (Workplane). So, Daysim (with its current old version Radiance binaries) can do that; isn't it? At the same time, one can still say that simulations are based on the powerful Radiance tools, does that sound right, too?

So far, I don't think I still need to use BSDF as there is no need for 3- nor 5-phase methods for such level of work!

Can you please correct me if there is something wrong with my understanding/assumptions?

Best regards
Ikrima

-----Original Message-----
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Sent: 11 August 2015 17:00
To: [email protected]
Subject: Radiance-general Digest, Vol 138, Issue 22

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    1. Re: rcontrib with 2-phase method? (J. Alstan Jakubiec)

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Message: 1
Date: Tue, 11 Aug 2015 23:38:14 +0800
From: "J. Alstan Jakubiec" <[email protected]>
To: [email protected]
Cc: [email protected]
Subject: Re: [Radiance-general] rcontrib with 2-phase method?
Message-ID: <[email protected]>
Content-Type: text/plain; charset="windows-1252"; Format="flowed"

Dear Ikrima,

Daysim comes with its own special version of the Radiance binaries that can be downloaded at the Daysim website <http://daysim.ning.com/>. These get stored in c:\DAYSIM\bin\ after installation on Windows.
Unfortunately the binaries are based on an older Radiance version, so you miss some options like using BSDF data. Still, Daysim is perfectly serviceable for most cases. I hope I understood your question.

Best,
Alstan

On 8/11/2015 11:09 PM, Guglielmetti, Robert wrote:

I really have no experience with Daysim at this point so I really am
not the best person to answer this one, sorry. In a general sense,
with respect to Daysim and Radiance you'd use one or the other, not
both. The Radiance daylight coefficient method (i.e. using rcontrib
and other tools in Radiance to do a 2-phase annual simulation) *is*
basically the same thing as Daysim. Hope this helps but it probably
doesn't. =/

On 8/11/15, 4:54 AM, "Ikrima Amaireh" <[email protected]> wrote:

Dear Robert,

Thanks for making clear that using rcontrib and using 3/5 phase
methods need a recent version of radiance. does that apply to using
2-phse
(Daysim) or one can still use old versions of radiance (as I have a
problem yet with installing recent versions of radiance and link it
with Daysim tool)?

Many thanks for you in advance:

Regards,
ikriam

------------------------------

Message: 2
Date: Mon, 10 Aug 2015 17:03:49 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
         <[email protected]>
Subject: Re: [Radiance-general] Ray-tracing with Radiance
Message-ID: <D1EE1EEF.1B923%[email protected]>
Content-Type: text/plain; charset="us-ascii"

There is a daysim-specific mailing list that may be useful for some
of your questions:

http://www.radiance-online.org/community/mailing-lists/subscribe/radi
ance-
d
aysim

I can tell you that if you're planning to use rcontrib and do 3- or
5-phase type stuff, you definitely should be using a recent version
of Radiance. Either build from latest source, or use one of the NREL
pre-built packages (I recommend v5):

https://github.com/NREL/Radiance/releases/tag/5.0.a.3

On 8/10/15, 9:14 AM, "Ikrima Amaireh" <[email protected]> wrote:

Dear Germ?n,

Many thanks for you. I agree with you totally that all Radiance
works need to apply ray-tracing approach as the core principle of it.
However, what I meant by using ray-tracing in radiance, was the
using of RTRACE directly through stand-alone radiance tool (as you
kindly mentioned).

As you clarified, Daysim uses 2-phase method to do annual simulation
(2nd
phase) fast, based on pre-calculated Daylight Coefficient Matrix
(1st phase). Now, if I need to produce the illuminance levels
(produced by specific CFS) at the Workplane under static scene, can
I still use Daysim for that? Or, shall I stick to RTRACE tool
directly through pure Radiance?

And, if I have to stick to using Pure Radiance (RTRACE), is the
method detailed in the attached document (hope, you see that: where
Geometry and Workplane sensors are built in Ecotect and directly
exported to Radiance engine), is it still valid?

Finally, in both cases (using pure Radiance and/or Daysim), shall we
replace the Radiance tool (works as engine) by the latest released
version (i.e. Version 4.2 or recent?) as the one works with
Ecotect-Radiance approach (I'm not sure about Daysim, yet) is old
version (2.0; in think!)?

Really, I am grateful to you for your appreciated help and looking
to hear from you again :slight_smile:

Regards,

Ikrima

As some of you may remember, I am trying to model a set of CFS to
compare their effect on indoor horizontal illuminance of a room.

So far, I have been advised by you for several stages, which really
helped me a lot for better understanding of radiance and how it works.
Now, I have a question about how I use ray-tracing method in radiance?
Is it similar to the way explained through the following attachment?
As here, calculations are run using Radiance engine but Ecotect or
Daysim interface (for geometry modelling and material assignment).
Document:
http://web.mit.edu/sustainabledesignlab/projects/TeachingResources/G
ett
ing
StartedwithEcotectRadianceDaysim.pdf

I hope if you can kindly advise me on that asap, please?

Ikrima,

Strictly speaking, Radiance always use ray-tracing. Whenever you
call RPICT, RTRACE or RCONTRIB, there will always be a ray-tracing
simulation performed. However, when you want to perform annual
simulations, you will want to do as few ray-tracing simulations as
possible since they take time.
RTRACE, for example, is a method used to calculate the illuminance
or luminance of a point (sensor) in a static scene. Doing this for a
whole year would require 8760 or more RTRACE calls, which means 8760
or more ray-tracing simulations, which is slow.

Accordingly, Daysim (which uses the 2-phase method) runs one
ray-tracing simulation that calculates the Daylight Coefficient
matrix (this can be done in pure radiance by using RCONTRIB). This
matrix relates the sensors
(workplane?) in the scene with the sky, mich means that you can
modify the sky and quickly evaluate illuminance in the same points.
This allows performing annual simulations fast (only the sky changes
in a static annual simulation). 3 and 5 phase method are extensions
to this that allow also modifying the CFSs in the scene.

Hope that clarify a little bit.

-----Original Message-----
From: [email protected]
[mailto:[email protected]]
Sent: 10 August 2015 14:20
To: [email protected]
Subject: Radiance-general Digest, Vol 138, Issue 12

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         [email protected]

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    1. Re: Ray-tracing with Radiance (Germ?n Molina Larrain)

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Message: 1
Date: Mon, 10 Aug 2015 10:19:18 -0300
From: Germ?n Molina Larrain <[email protected]>
To: Radiance general discussion
<[email protected]>
Subject: Re: [Radiance-general] Ray-tracing with Radiance
Message-ID:

<CAF-iH4LVHB_V+Vmy-mSiv2EtUE25KDxtTAyJfao5Mi6fzFDU1g@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

Ikrima,

Strictly speaking, Radiance always use ray-tracing. Whenever you
call RPICT, RTRACE or RCONTRIB, there will always be a ray-tracing
simulation performed. However, when you want to perform annual
simulations, you will want to do as few ray-tracing simulations as
possible since they take time.
RTRACE, for example, is a method used to calculate the illuminance
or luminance of a point (sensor) in a static scene. Doing this for a
whole year would require 8760 or more RTRACE calls, which means 8760
or more ray-tracing simulations, which is slow.

Accordingly, Daysim (which uses the 2-phase method) runs one
ray-tracing simulation that calculates the Daylight Coefficient
matrix (this can be done in pure radiance by using RCONTRIB). This
matrix relates the sensors
(workplane?) in the scene with the sky, mich means that you can
modify the sky and quickly evaluate illuminance in the same points.
This allows performing annual simulations fast (only the sky changes
in a static annual simulation). 3 and 5 phase method are extensions
to this that allow also modifying the CFSs in the scene.

Hope that clarify a little bit.

Best,

Germ?n

2015-08-10 8:51 GMT-03:00 Ikrima Amaireh <[email protected]>:

Hello Robert,
Hello all,

As some of you may remember, I am trying to model a set of CFS to
compare their effect on indoor horizontal illuminance of a room. So
far, I have been advised by you for several stages, which really
helped me a lot for better understanding of radiance and how it works.

Now, I have a question about how I use ray-tracing method in radiance?
Is it similar to the way explained through the following attachment?
As here, calculations are run using Radiance engine but Ecotect or
Daysim interface (for geometry modelling and material assignment).

Document:
http://web.mit.edu/sustainabledesignlab/projects/TeachingResources/
Ge t tingStartedwithEcotectRadianceDaysim.pdf

I hope if you can kindly advise me on that asap, please?

Best regards
Ikrima

-----Original Message-----
From: [email protected] [mailto:
[email protected]]
Sent: 12 July 2015 20:37
To: [email protected]
Subject: Radiance-general Digest, Vol 137, Issue 12

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     1. Git for Windows and starting tutorials (Ikrima Amaireh)

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Message: 1
Date: Sun, 12 Jul 2015 20:36:19 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
          <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] Git for Windows and starting tutorials
Message-ID:
          <
D697763F9F216044A99BC674C00561961358CA9C4C@EXCHANGE1.ad.nottingham.ac.
>

Content-Type: text/plain; charset="us-ascii"

Hi Robert,

Many thanks for your help.

I have installed Git for Windows as you adviced :slight_smile: Now, Before I
start with 3 or 5-phase tutorials, I'm thinking to go through
"radiance tutorial"
(by Axel Jacobs) as a beginner with almost a shallow
knowledge/experience of radiance. So, do recommend this (radiance
tutorial would be enough to start with 3 or 5-phase methods and
understanding of BSDF data approach,
etc) or advice another tutorial/source for better understanding of
radiance basics (using command prompt)?

Many thanks again :slight_smile:

Regards
Ikrima

------------------------------

Message: 2
Date: Fri, 10 Jul 2015 15:52:23 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
          <[email protected]>
Subject: Re: [Radiance-general] Radiance-general Digest, Vol 137,
          Issue 8
Message-ID: <D1C542EA.1AE88%[email protected]>
Content-Type: text/plain; charset="us-ascii"

OK so it sounds like you first tried the Windows installer
(presumably a NREL-provided one such as this:
https://github.com/NREL/Radiance/releases/download/5.0.a.3/radiance-5.
0.a-w in64.exe), and this most likely worked fine, you just had
some issues actually *doing* anything with it. This is normal. =)

I recommend you install Git for windows
(https://msysgit.github.io/), as that will add a little BASH
emulator in your Windows system. This way you can run most of the
commands exactly as they appear in most of the tutorials out there
that are written from a UNIX perspective (as you point out). If you
run the "Git BASH shell" you will be able to try out all the multi-phase methods, use and generate BSDFs, etc.
Once you have Git for Windows installed, head over to Andy McNeil's
tutorials for 3- and 5-phase, fire up the Git BASH shell (it'll be
in the Git program group in the Windows start menu), and get started!

One thing to keep in mind is that when running any commands that
read/write data (e.g. rcontrib), be sure to use ASCII format rather
than float. Windows has issues with float data (among many other
things).

Good luck!

- Rob

On 7/10/15, 8:08 AM, "Ikrima Amaireh" <[email protected]> wrote:

Hi Robert,

My PC is running on Windows 7 Enterprise.
Initially, I installed Radiance for Window using its installer but
I found that most of the tutorials are provided for pc with Linux
and/or Linux-like operating systems; So I had to install try
learnix (that did not work) and Ubuntu (also did not work)!
Finally, I tried to use Cygwin to run Radiance on Window OS. I
could install Cygwin (works fine), Xming (not sure if working) and
Radiance (not all its programs are working!).

I'm a bit confused as I'm not sure if running Radiance on windows
using Cygwin will be enough for carrying my work. For example, can
I work out phases methods and generate BSDF data?

I wish if you can help me to do that.

Many thanks
ikrima

------------------------------

Message: 3
Date: Thu, 9 Jul 2015 16:44:49 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
        <[email protected]>
Subject: Re: [Radiance-general] Could not install Radiance!!!
Message-ID: <D1C400AC.1ADAC%[email protected]>
Content-Type: text/plain; charset="us-ascii"

Hi Ikrima,

We'll need a bit more info, here. What OS are you on? How are you
attempting to install it (using an installer, compiling from
source, or what)? What happens when you try??

On 7/9/15, 10:38 AM, "Ikrima Amaireh" <[email protected]> wrote:

Hi all,

After one a few weeks of trying, I could not manage to install
radiance properly. I am almost disappointed! Please any help?

Regards
Ikrima

This message and any attachment are intended solely for the
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immediately delete it.

Please do not use, copy or disclose the information contained in
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------------------------------

Message: 3
Date: Fri, 10 Jul 2015 17:34:30 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
          <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] Modelling CFS
Message-ID:
          <
D697763F9F216044A99BC674C00561961358CA9BAF@EXCHANGE1.ad.nottingham.ac.
>

Content-Type: text/plain; charset="us-ascii"

Hi all,

Thanks Robert and Larrain for your detailed replies, that helped me
a lot.

I would summarise here what I got form your appreciated replies, as
following:
- Radiance is convenient and best of tools to model daylighting due
to its ray-tracing method.
- 3 or 5-phases methods are used to facilitate the calculations.
- Generating BSDF data is also used to facilitate these
calculations but it is limited to Klems resolution of some CFS.

Initially, I'm not planning to do annual calculations. It's just
for specific hours of the day and the target is to produce a
illuminance levels for indoor grid under different CFSs. Hence,
according to my understanding from Larrain words, I can use either
2-phase or Ray-tracing methods. My question is how can I
draw/define the CFS geometry and Space for these calculations? Is
it similar to the way use in Ecotect/Radiance calculations?

Regards
Ikrima

   -----Original Message-----
From: [email protected] [mailto:
[email protected]]
Sent: 09 July 2015 19:56
To: [email protected]
Subject: Radiance-general Digest, Vol 137, Issue 8

Send Radiance-general mailing list submissions to
          [email protected]

To subscribe or unsubscribe via the World Wide Web, visit

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          [email protected]

When replying, please edit your Subject line so it is more specific
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"Re: Contents of Radiance-general digest..."

Today's Topics:

     1. CFS with Radiance (Ikrima Amaireh)
     2. Could not install Radiance!!! (Ikrima Amaireh)
     3. Re: Could not install Radiance!!! (Guglielmetti, Robert)
     4. Re: CFS with Radiance (Guglielmetti, Robert)
     5. Re: CFS with Radiance (Germ?n Molina Larrain)

-------------------------------------------------------------------
--
-

Message: 1
Date: Thu, 9 Jul 2015 17:26:29 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
          <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] CFS with Radiance
Message-ID:
          <
D697763F9F216044A99BC674C00561961358CA9710@EXCHANGE1.ad.nottingham.ac.
>

Content-Type: text/plain; charset="us-ascii"

Hi G. Larrain,

Thanks for your detailed clarification (below).

I wonder if you kindly can help me toward better understanding and
answering the following:

We agreed that for daylight modelling of spaces with CFS, Radiance
is a suitable tool as it applies ray-tracing method. And for annual
and/or climate-based daylight calculations, as calculation time
becomes a critical factor, using BSDF data for CFS is highly
recommended to tackle the task with radiance (using phases methods).
However:

- if someone needs to perform daylight calculations for given space
with different CFS (different cases for comparison purposes) to get
illumination levels for horizontal grid points (and not pictures
nor scenes), is Radiance still the most convenient option?
- is it still needed to use any of the phase methods (2, 3 or 5)?
- most importantly, is it still needed to get BSDF data for CFS or
just can model the detailed CFS in Radiance (and, if yes, how?)

Many thanks for your kind help :slight_smile:

Regards
Ikrima

"Ikrima,

I am going to try to build the puzzle of CFS, Phases, BSDF and
calculations.... at least the way I understand it.

*CFS* are those systems that, via interreflection or other light
transport phenomena, redirect light (or solar radiation). Thus, in
order to get a reliable result you will have to consider all the
phenomena involved.
Then, *common
simple performance indexes*, such as the miss-used Shading
Coefficient and the Aperture Percentage, *always loose a lot of
information, trying to reduce all the complex behavior of a CFS to
one single number*. We all know that venetian blinds are more
"transparent" from certain viewing directions than from others,
but these performance indexes do not tell you that.

Now... Radiance can certainly perform calculations of spaces with
CFS using its "common" Ray-tracing. However, this may be slow for
some purposes (i.e.
annual simulations and climate-based daylight modelling), and *this
is why 2, 3 and 5 phase methods have been developed*. The *BSDF*
representation, I would say, goes in the same direction... It allow
summarizing all the bounces, reflections, refractions, etc. that
occure withing the CFS in a single matrix or tensor.* By using
BSDFs*, Radiance itself and other tools (i.e. EnergyPlus) can treat
CFS as blackboxes, avoiding all the opcits within the system. A
BSDF that uses the Klems Full representation has
21,045 numbers (instead of one, such as the Shading Coefficient).

Being said all that, I would not trust a calculation method unless
it can actually deal with the optics of a CFS that is drawn and/or
it can use BSDF (or similar) information.

Lets remember that a perforated screen, a venetian blind, a light
diffusing device can all have a Shading Coefficient of 50%, but all
of them will behave very differently. I made some presentations
about this on my previous work (we sold complex Shading Devices),
trying to promote the use of BSDF in EnergyPlus calculations... the
differences (in solar heat gains) were more than considerable.

I hope that someone else gives us his/her perspective on this topic...
there are a lot of concepts that I might be misunderstanding.

Best!"

This message and any attachment are intended solely for the
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received this message in error, please send it back to me, and immediately delete it.

Please do not use, copy or disclose the information contained in
this message or in any attachment. Any views or opinions expressed
by the author of this email do not necessarily reflect the views of
the University of Nottingham.

This message has been checked for viruses but the contents of an
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your computer system, you are advised to perform your own checks.
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------------------------------

Message: 2
Date: Thu, 9 Jul 2015 17:38:41 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
          <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] Could not install Radiance!!!
Message-ID:
          <
D697763F9F216044A99BC674C00561961358CA9719@EXCHANGE1.ad.nottingham.ac.
>

Content-Type: text/plain; charset="us-ascii"

Hi all,

After one a few weeks of trying, I could not manage to install
radiance properly. I am almost disappointed! Please any help?

Regards
Ikrima

This message and any attachment are intended solely for the
addressee and may contain confidential information. If you have
received this message in error, please send it back to me, and immediately delete it.

Please do not use, copy or disclose the information contained in
this message or in any attachment. Any views or opinions expressed
by the author of this email do not necessarily reflect the views of
the University of Nottingham.

This message has been checked for viruses but the contents of an
attachment may still contain software viruses which could damage
your computer system, you are advised to perform your own checks.
Email communications with the University of Nottingham may be
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------------------------------

Message: 3
Date: Thu, 9 Jul 2015 16:44:49 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
          <[email protected]>
Subject: Re: [Radiance-general] Could not install Radiance!!!
Message-ID: <D1C400AC.1ADAC%[email protected]>
Content-Type: text/plain; charset="us-ascii"

Hi Ikrima,

We'll need a bit more info, here. What OS are you on? How are you
attempting to install it (using an installer, compiling from
source, or what)? What happens when you try??

On 7/9/15, 10:38 AM, "Ikrima Amaireh" <[email protected]> wrote:

Hi all,

After one a few weeks of trying, I could not manage to install
radiance properly. I am almost disappointed! Please any help?

Regards
Ikrima

This message and any attachment are intended solely for the
addressee and may contain confidential information. If you have
received this message in error, please send it back to me, and

immediately delete it.

Please do not use, copy or disclose the information contained in
this message or in any attachment. Any views or opinions
expressed by the author of this email do not necessarily reflect
the views of the University of Nottingham.

This message has been checked for viruses but the contents of an
attachment may still contain software viruses which could damage
your computer system, you are advised to perform your own checks.
Email communications with the University of Nottingham may be
monitored as permitted by UK legislation.

_______________________________________________
Radiance-general mailing list
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------------------------------

Message: 4
Date: Thu, 9 Jul 2015 17:29:39 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
          <[email protected]>
Subject: Re: [Radiance-general] CFS with Radiance
Message-ID: <D1C40477.1ADCA%[email protected]>
Content-Type: text/plain; charset="us-ascii"

Some very quick replies and clarifications within:

On 7/9/15, 10:26 AM, "Ikrima Amaireh" <[email protected]> wrote:

Hi G. Larrain,

Thanks for your detailed clarification (below).

I wonder if you kindly can help me toward better understanding and
answering the following:

We agreed that for daylight modelling of spaces with CFS, Radiance
is a suitable tool as it applies ray-tracing method. And for
annual and/or climate-based daylight calculations, as calculation
time becomes a critical factor, using BSDF data for CFS is highly
recommended to tackle the task with radiance (using phases methods).

However:

BSDF data in an annual simulation context is generally limited to
Klems basis BSDF data, which may not be high enough resolution for
some CFS. And the 5-phase method, which can circumvent this, is not
necessarily "quick".
This is all still very much a quandary and the newest daylight
metrics have added confusion to all of this, IMO.

- if someone needs to perform daylight calculations for given
space with different CFS (different cases for comparison purposes)
to get illumination levels for horizontal grid points (and not
pictures nor scenes), is Radiance still the most convenient option?

Absolutely. The lack of an image-as-output requirement does not
change the fact that ray tracing is a good/convenient algorithm
option for daylight simulation problems, especially when dealing
with diffusing media and CFS in general. BSDFs allow you to do
lots of "what-ifs", relatively quickly, but are beholden to the
limitations of the resolution of the BSDF.

- is it still needed to use any of the phase methods (2, 3 or 5)?

Is what still needed? BSDF data? Ray tracing? I don't know of other
lighting simulation tools that can employ the multiphase methods. I
would say BSDF data is optional for 2-phase, required for 3-phase,
and optional for 5-phase.

- most importantly, is it still needed to get BSDF data for CFS or
just can model the detailed CFS in Radiance (and, if yes, how?)

Again I'm confused as to what "it" is. A couple of approaches are
available to you in general. If you have a geometric model of the
CFS you can use Radiance (genBSDF) to make a BSDF of the CFS and
use that in a 3- or 5-phase context. However in an
annual/climate-based simulation context, you will be stuck with a
Klems basis BSDF and that will not be very good resolution for a
lot of CFS; here you may want to use the 5-phase method and stick
the actual CFS geometry in the building model.

Some things to consider here are the photon map, now a part of
Radiance proper, or using the 2-phase method where appropriate. By
2-phase method I mean generating a daylight matrix for your
calculation points (or view), and modeling the window material as-is.
If the "CFS" is a shade cloth, you can approximate that with a
Radiance "trans". Same for translucent panels.
With this single daylight matrix, you can throw a vector of sky
matrices at it and get an annual climate-based result very quickly.
Problem is, we want to do stuff to the windows, sometimes at the
time step level, so:

Blinds and compact daylight redirection devices (e.g. Lightlouver)
are best represented as BSDF, and if most of the redirected flux
is headed up and away from the points of interest, a Klems basis
BSDF is good enough IMO. In these cases you could use the 3-phase method.
Problem is when you have a BSDF for blinds, and you also want to
simulate the blinds-up condition (i.e. clear, specularly
transmitting glass). Using a Klems basis BSDF for this is
sub-optimal. You end up needing to do two annual simulations, one
as 2-phase for the clear glass scenario, and again as a 3-phase
(with a blinds BSDF for the transmission
matrix) for the blinds down condition. If you have a lot of
different window groups, your simulation space can get large in a
hurry. But it's still do-able and you can get results that tell a
story you simply couldn't tell 5 years ago, informing the newest
daylight metrics as well.

------------------------------

Message: 5
Date: Thu, 9 Jul 2015 15:56:11 -0300
From: Germ?n Molina Larrain <[email protected]>
To: Radiance general discussion
<[email protected]>
Subject: Re: [Radiance-general] CFS with Radiance
Message-ID:
          <CAF-iH4LSr=y12F1khTrHh6hnf-kS=EmaFuo8uWKvHqMs=
[email protected]>
Content-Type: text/plain; charset="utf-8"

I must say that I agree with Rob, however, a short answer that
might help.

For evaluating illuminance levels in a space with different CFS
you, strictly speaking, DO NOT HAVE TO do anything. You may choose
between different methods that have some pros and cons.

*ray-tracing*

     - Requires ray-tracing for each time-step and each system,
which is slow
     (*four systems simulated annualy in an hourly basis --> 4*8760

35,040
     simulations*.)
     - As accurate as it gets, if options are defined correctly.

*2 phase method*

     - Do not need the BSDF
     - Requires ray-tracing for each CFS (*4 systems --> 4 ray-tracing
     simulations*)
     - After ray-tracing, annual simulation is fast.

*3-phase method:*

     - Requires BSDF data in KLEMS basis, which may be slow to compute,
     unless it can be exported from WINDOW, for example, or such data has
     already been calculated (the idea is to make a database, I think).
     - Does not really work well for specular systems (Klems patches
are too
     big)
     - Requires 2 ray-tracing runs, always (*4 systems --> 2 ray-tracing
     simulations*)
     - After ray-tracing and BSDF calculation, annual simulation is
fast

*5-phase method:*

     - Requires BSDF data in KLEMS basis AND/OR Tensor tree format,
which
     may be slow to compute, unless it can be exported from WINDOW,
for example,
     or such data has already been calculated (the idea is to make a
database, I
     think).
     - Works well for specular systems
     - Requires 4 ray-tracing runs + 1 for each system, always (*4
systems
     --> 4+1 = 5 ray-tracing simulations*)
     - Hard to code...?
     - After ray-tracing and BSDF calculation, annual simulation is
fast

I would not say there is a recipe. If you have to choose between 1
or
2 CFSs, maybe it is faster to just draw them and use the 2 phase
method (or ray-tracing if an annual simulaton is not required). On
the contrary, if you are going to test 10 different CFSs, 3 and 5
phases may make sense, since you reduce the expensive ray-tracing
calculations... However, this will also depend on weather you have
the BSDF data AND/OR if it makes sense to calculate it and store it
AND/OR if you intend to simulate a dynamically controlled CFS.

Best!

2015-07-09 14:29 GMT-03:00 Guglielmetti, Robert <
[email protected]>:

Some very quick replies and clarifications within:

On 7/9/15, 10:26 AM, "Ikrima Amaireh" <[email protected]> wrote:

Hi G. Larrain,

Thanks for your detailed clarification (below).

I wonder if you kindly can help me toward better understanding
and answering the following:

We agreed that for daylight modelling of spaces with CFS,
Radiance is a suitable tool as it applies ray-tracing method. And
for annual and/or climate-based daylight calculations, as
calculation time becomes a critical factor, using BSDF data for
CFS is highly recommended to tackle the task with radiance (using phases methods).

However:

BSDF data in an annual simulation context is generally limited to
Klems basis BSDF data, which may not be high enough resolution for
some CFS. And the 5-phase method, which can circumvent this, is
not

necessarily "quick".

This is all still very much a quandary and the newest daylight
metrics have added confusion to all of this, IMO.

- if someone needs to perform daylight calculations for given
space with different CFS (different cases for comparison
purposes) to get illumination levels for horizontal grid points
(and not pictures nor scenes), is Radiance still the most convenient option?

Absolutely. The lack of an image-as-output requirement does not
change the fact that ray tracing is a good/convenient algorithm
option for daylight simulation problems, especially when dealing
with diffusing media and CFS in general. BSDFs allow you to do
lots of "what-ifs", relatively quickly, but are beholden to the
limitations of the

resolution of the BSDF.

- is it still needed to use any of the phase methods (2, 3 or 5)?

Is what still needed? BSDF data? Ray tracing? I don't know of
other lighting simulation tools that can employ the multiphase
methods. I would say BSDF data is optional for 2-phase, required
for 3-phase, and optional for 5-phase.

- most importantly, is it still needed to get BSDF data for CFS
or just can model the detailed CFS in Radiance (and, if yes,
how?)

Again I'm confused as to what "it" is. A couple of approaches are
available to you in general. If you have a geometric model of the
CFS you can use Radiance (genBSDF) to make a BSDF of the CFS and
use that in a 3- or 5-phase context. However in an
annual/climate-based simulation context, you will be stuck with a
Klems basis BSDF and that will not be very good resolution for a
lot of CFS; here you may want to use the 5-phase method and stick
the actual CFS geometry in the

building model.

Some things to consider here are the photon map, now a part of
Radiance proper, or using the 2-phase method where appropriate. By
2-phase method I mean generating a daylight matrix for your
calculation points (or view), and modeling the window material as-is.
If the "CFS" is a shade cloth, you can approximate that with a
Radiance

"trans". Same for translucent panels.

With this single daylight matrix, you can throw a vector of sky
matrices at it and get an annual climate-based result very quickly.
Problem is, we want to do stuff to the windows, sometimes at the
time

step level, so:

Blinds and compact daylight redirection devices (e.g. Lightlouver)
are best represented as BSDF, and if most of the redirected flux
is headed up and away from the points of interest, a Klems basis
BSDF is good enough IMO. In these cases you could use the 3-phase method.
Problem is when you have a BSDF for blinds, and you also want to
simulate the blinds-up condition (i.e. clear, specularly
transmitting glass). Using a Klems basis BSDF for this is
sub-optimal. You end up needing to do two annual simulations, one
as 2-phase for the clear glass scenario, and again as a 3-phase
(with a blinds BSDF for the transmission
matrix) for the blinds down condition. If you have a lot of
different window groups, your simulation space can get large in a
hurry. But it's still do-able and you can get results that tell a
story you simply couldn't tell 5 years ago, informing the newest
daylight metrics

as well.

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Dear Alstan,

Many thanks for your response. I'll do and let you know if there is more inquires, if possible?

Regards
ikrima

···

-----Original Message-----
From: [email protected] [mailto:[email protected]]
Sent: 17 August 2015 03:54
To: [email protected]
Subject: Radiance-general Digest, Vol 138, Issue 31

Send Radiance-general mailing list submissions to
  [email protected]

To subscribe or unsubscribe via the World Wide Web, visit
  http://www.radiance-online.org/mailman/listinfo/radiance-general
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When replying, please edit your Subject line so it is more specific
than "Re: Contents of Radiance-general digest..."

Today's Topics:

   1. Gensky (Jiajie Zhu)
   2. Re: Gensky (Jia Hu)
   3. Re: rcontrib with 2-phase method? (J. Alstan Jakubiec)

----------------------------------------------------------------------

Message: 1
Date: Sun, 16 Aug 2015 22:07:55 +0100
From: "Jiajie Zhu" <[email protected]>
To: <[email protected]>
Subject: [Radiance-general] Gensky
Message-ID: <[email protected]>
Content-Type: text/plain; charset="us-ascii"

Hi

Could someone tell me how Radiance calculate the radiation values for the
sun using gensky. I mean where do these values come from, based on what
theory or which model.

Many Thanks,

Jiajie

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Message: 2
Date: Sun, 16 Aug 2015 17:51:00 -0400
From: Jia Hu <[email protected]>
To: Radiance general discussion <[email protected]>
Subject: Re: [Radiance-general] Gensky
Message-ID:
  <CABzgtwqrjAuQ0nL6xY3XUcyGsXqcJQX4FhJjbLCPjLJEmvfwPg@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

Hi Jiajie,

you can read the man page and some materials.
*Gensky* produces a RADIANCE scene description for the CIE standard sky
distribution,
http://radsite.lbl.gov/radiance/man_html/gensky.1.html

http://www.bozzograo.net/radiance/index.php?name=FAQ#faq5
http://www.radiance-online.org/pipermail/radiance-general/2003-October/001087.html

On Sun, Aug 16, 2015 at 5:07 PM, Jiajie Zhu <[email protected]> wrote:

Hi

Could someone tell me how Radiance calculate the radiation values for the
sun using gensky. I mean where do these values come from, based on what
theory or which model.

Many Thanks,

Jiajie

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Message: 3
Date: Wed, 12 Aug 2015 23:09:19 +0800
From: "J. Alstan Jakubiec" <[email protected]>
To: [email protected]
Subject: Re: [Radiance-general] rcontrib with 2-phase method?
Message-ID: <[email protected]>
Content-Type: text/plain; charset="windows-1252"; Format="flowed"

Dear Ikrima,

Yes, I think that is a fair series statements, and it sounds right. You
may want to read the Daysim paper in order to understand the methods a
bit more,

    Reinhart, Christoph F., and Oliver Walkenhorst. "Validation of
    dynamic RADIANCE-based daylight simulations for a test office with
    external blinds." /Energy and Buildings/ 33.7 (2001): 683-697.

Best,
Alstan

On 8/12/2015 12:21 AM, Ikrima Amaireh wrote:

Dear Alstan,

Yes, you actually did :slight_smile:

What exactly I want to do is: modelling different CFS to assess their effect on indoor illuminance (Workplane). So, Daysim (with its current old version Radiance binaries) can do that; isn't it? At the same time, one can still say that simulations are based on the powerful Radiance tools, does that sound right, too?

So far, I don't think I still need to use BSDF as there is no need for 3- nor 5-phase methods for such level of work!

Can you please correct me if there is something wrong with my understanding/assumptions?

Best regards
Ikrima

-----Original Message-----
From: [email protected] [mailto:[email protected]]
Sent: 11 August 2015 17:00
To: [email protected]
Subject: Radiance-general Digest, Vol 138, Issue 22

Send Radiance-general mailing list submissions to
         [email protected]

To subscribe or unsubscribe via the World Wide Web, visit
         http://www.radiance-online.org/mailman/listinfo/radiance-general
or, via email, send a message with subject or body 'help' to
         [email protected]

You can reach the person managing the list at
         [email protected]

When replying, please edit your Subject line so it is more specific than "Re: Contents of Radiance-general digest..."

Today's Topics:

    1. Re: rcontrib with 2-phase method? (J. Alstan Jakubiec)

----------------------------------------------------------------------

Message: 1
Date: Tue, 11 Aug 2015 23:38:14 +0800
From: "J. Alstan Jakubiec" <[email protected]>
To: [email protected]
Cc: [email protected]
Subject: Re: [Radiance-general] rcontrib with 2-phase method?
Message-ID: <[email protected]>
Content-Type: text/plain; charset="windows-1252"; Format="flowed"

Dear Ikrima,

Daysim comes with its own special version of the Radiance binaries that can be downloaded at the Daysim website <http://daysim.ning.com/>. These get stored in c:\DAYSIM\bin\ after installation on Windows.
Unfortunately the binaries are based on an older Radiance version, so you miss some options like using BSDF data. Still, Daysim is perfectly serviceable for most cases. I hope I understood your question.

Best,
Alstan

On 8/11/2015 11:09 PM, Guglielmetti, Robert wrote:

I really have no experience with Daysim at this point so I really am
not the best person to answer this one, sorry. In a general sense,
with respect to Daysim and Radiance you'd use one or the other, not
both. The Radiance daylight coefficient method (i.e. using rcontrib
and other tools in Radiance to do a 2-phase annual simulation) *is*
basically the same thing as Daysim. Hope this helps but it probably
doesn't. =/

On 8/11/15, 4:54 AM, "Ikrima Amaireh" <[email protected]> wrote:

Dear Robert,

Thanks for making clear that using rcontrib and using 3/5 phase
methods need a recent version of radiance. does that apply to using
2-phse
(Daysim) or one can still use old versions of radiance (as I have a
problem yet with installing recent versions of radiance and link it
with Daysim tool)?

Many thanks for you in advance:

Regards,
ikriam

------------------------------

Message: 2
Date: Mon, 10 Aug 2015 17:03:49 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
         <[email protected]>
Subject: Re: [Radiance-general] Ray-tracing with Radiance
Message-ID: <D1EE1EEF.1B923%[email protected]>
Content-Type: text/plain; charset="us-ascii"

There is a daysim-specific mailing list that may be useful for some
of your questions:

http://www.radiance-online.org/community/mailing-lists/subscribe/radi
ance-
d
aysim

I can tell you that if you're planning to use rcontrib and do 3- or
5-phase type stuff, you definitely should be using a recent version
of Radiance. Either build from latest source, or use one of the NREL
pre-built packages (I recommend v5):

https://github.com/NREL/Radiance/releases/tag/5.0.a.3

On 8/10/15, 9:14 AM, "Ikrima Amaireh" <[email protected]> wrote:

Dear Germ?n,

Many thanks for you. I agree with you totally that all Radiance
works need to apply ray-tracing approach as the core principle of it.
However, what I meant by using ray-tracing in radiance, was the
using of RTRACE directly through stand-alone radiance tool (as you
kindly mentioned).

As you clarified, Daysim uses 2-phase method to do annual simulation
(2nd
phase) fast, based on pre-calculated Daylight Coefficient Matrix
(1st phase). Now, if I need to produce the illuminance levels
(produced by specific CFS) at the Workplane under static scene, can
I still use Daysim for that? Or, shall I stick to RTRACE tool
directly through pure Radiance?

And, if I have to stick to using Pure Radiance (RTRACE), is the
method detailed in the attached document (hope, you see that: where
Geometry and Workplane sensors are built in Ecotect and directly
exported to Radiance engine), is it still valid?

Finally, in both cases (using pure Radiance and/or Daysim), shall we
replace the Radiance tool (works as engine) by the latest released
version (i.e. Version 4.2 or recent?) as the one works with
Ecotect-Radiance approach (I'm not sure about Daysim, yet) is old
version (2.0; in think!)?

Really, I am grateful to you for your appreciated help and looking
to hear from you again :slight_smile:

Regards,

Ikrima

As some of you may remember, I am trying to model a set of CFS to
compare their effect on indoor horizontal illuminance of a room.

So far, I have been advised by you for several stages, which really
helped me a lot for better understanding of radiance and how it works.
Now, I have a question about how I use ray-tracing method in radiance?
Is it similar to the way explained through the following attachment?
As here, calculations are run using Radiance engine but Ecotect or
Daysim interface (for geometry modelling and material assignment).
Document:
http://web.mit.edu/sustainabledesignlab/projects/TeachingResources/G
ett
ing
StartedwithEcotectRadianceDaysim.pdf

I hope if you can kindly advise me on that asap, please?

Ikrima,

Strictly speaking, Radiance always use ray-tracing. Whenever you
call RPICT, RTRACE or RCONTRIB, there will always be a ray-tracing
simulation performed. However, when you want to perform annual
simulations, you will want to do as few ray-tracing simulations as
possible since they take time.
RTRACE, for example, is a method used to calculate the illuminance
or luminance of a point (sensor) in a static scene. Doing this for a
whole year would require 8760 or more RTRACE calls, which means 8760
or more ray-tracing simulations, which is slow.

Accordingly, Daysim (which uses the 2-phase method) runs one
ray-tracing simulation that calculates the Daylight Coefficient
matrix (this can be done in pure radiance by using RCONTRIB). This
matrix relates the sensors
(workplane?) in the scene with the sky, mich means that you can
modify the sky and quickly evaluate illuminance in the same points.
This allows performing annual simulations fast (only the sky changes
in a static annual simulation). 3 and 5 phase method are extensions
to this that allow also modifying the CFSs in the scene.

Hope that clarify a little bit.

-----Original Message-----
From: [email protected]
[mailto:[email protected]]
Sent: 10 August 2015 14:20
To: [email protected]
Subject: Radiance-general Digest, Vol 138, Issue 12

Send Radiance-general mailing list submissions to
         [email protected]

To subscribe or unsubscribe via the World Wide Web, visit

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or, via email, send a message with subject or body 'help' to
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When replying, please edit your Subject line so it is more specific
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"Re: Contents of Radiance-general digest..."

Today's Topics:

    1. Re: Ray-tracing with Radiance (Germ?n Molina Larrain)

--------------------------------------------------------------------
--

Message: 1
Date: Mon, 10 Aug 2015 10:19:18 -0300
From: Germ?n Molina Larrain <[email protected]>
To: Radiance general discussion
<[email protected]>
Subject: Re: [Radiance-general] Ray-tracing with Radiance
Message-ID:

<CAF-iH4LVHB_V+Vmy-mSiv2EtUE25KDxtTAyJfao5Mi6fzFDU1g@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

Ikrima,

Strictly speaking, Radiance always use ray-tracing. Whenever you
call RPICT, RTRACE or RCONTRIB, there will always be a ray-tracing
simulation performed. However, when you want to perform annual
simulations, you will want to do as few ray-tracing simulations as
possible since they take time.
RTRACE, for example, is a method used to calculate the illuminance
or luminance of a point (sensor) in a static scene. Doing this for a
whole year would require 8760 or more RTRACE calls, which means 8760
or more ray-tracing simulations, which is slow.

Accordingly, Daysim (which uses the 2-phase method) runs one
ray-tracing simulation that calculates the Daylight Coefficient
matrix (this can be done in pure radiance by using RCONTRIB). This
matrix relates the sensors
(workplane?) in the scene with the sky, mich means that you can
modify the sky and quickly evaluate illuminance in the same points.
This allows performing annual simulations fast (only the sky changes
in a static annual simulation). 3 and 5 phase method are extensions
to this that allow also modifying the CFSs in the scene.

Hope that clarify a little bit.

Best,

Germ?n

2015-08-10 8:51 GMT-03:00 Ikrima Amaireh <[email protected]>:

Hello Robert,
Hello all,

As some of you may remember, I am trying to model a set of CFS to
compare their effect on indoor horizontal illuminance of a room. So
far, I have been advised by you for several stages, which really
helped me a lot for better understanding of radiance and how it works.

Now, I have a question about how I use ray-tracing method in radiance?
Is it similar to the way explained through the following attachment?
As here, calculations are run using Radiance engine but Ecotect or
Daysim interface (for geometry modelling and material assignment).

Document:
http://web.mit.edu/sustainabledesignlab/projects/TeachingResources/
Ge t tingStartedwithEcotectRadianceDaysim.pdf

I hope if you can kindly advise me on that asap, please?

Best regards
Ikrima

-----Original Message-----
From: [email protected] [mailto:
[email protected]]
Sent: 12 July 2015 20:37
To: [email protected]
Subject: Radiance-general Digest, Vol 137, Issue 12

Send Radiance-general mailing list submissions to
          [email protected]

To subscribe or unsubscribe via the World Wide Web, visit

http://www.radiance-online.org/mailman/listinfo/radiance-general
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          [email protected]

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          [email protected]

When replying, please edit your Subject line so it is more specific
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"Re: Contents of Radiance-general digest..."

Today's Topics:

     1. Git for Windows and starting tutorials (Ikrima Amaireh)

-------------------------------------------------------------------
--
-

Message: 1
Date: Sun, 12 Jul 2015 20:36:19 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
          <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] Git for Windows and starting tutorials
Message-ID:
          <
D697763F9F216044A99BC674C00561961358CA9C4C@EXCHANGE1.ad.nottingham.ac.
>

Content-Type: text/plain; charset="us-ascii"

Hi Robert,

Many thanks for your help.

I have installed Git for Windows as you adviced :slight_smile: Now, Before I
start with 3 or 5-phase tutorials, I'm thinking to go through
"radiance tutorial"
(by Axel Jacobs) as a beginner with almost a shallow
knowledge/experience of radiance. So, do recommend this (radiance
tutorial would be enough to start with 3 or 5-phase methods and
understanding of BSDF data approach,
etc) or advice another tutorial/source for better understanding of
radiance basics (using command prompt)?

Many thanks again :slight_smile:

Regards
Ikrima

------------------------------

Message: 2
Date: Fri, 10 Jul 2015 15:52:23 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
          <[email protected]>
Subject: Re: [Radiance-general] Radiance-general Digest, Vol 137,
          Issue 8
Message-ID: <D1C542EA.1AE88%[email protected]>
Content-Type: text/plain; charset="us-ascii"

OK so it sounds like you first tried the Windows installer
(presumably a NREL-provided one such as this:
https://github.com/NREL/Radiance/releases/download/5.0.a.3/radiance-5.
0.a-w in64.exe), and this most likely worked fine, you just had
some issues actually *doing* anything with it. This is normal. =)

I recommend you install Git for windows
(https://msysgit.github.io/), as that will add a little BASH
emulator in your Windows system. This way you can run most of the
commands exactly as they appear in most of the tutorials out there
that are written from a UNIX perspective (as you point out). If you
run the "Git BASH shell" you will be able to try out all the multi-phase methods, use and generate BSDFs, etc.
Once you have Git for Windows installed, head over to Andy McNeil's
tutorials for 3- and 5-phase, fire up the Git BASH shell (it'll be
in the Git program group in the Windows start menu), and get started!

One thing to keep in mind is that when running any commands that
read/write data (e.g. rcontrib), be sure to use ASCII format rather
than float. Windows has issues with float data (among many other
things).

Good luck!

- Rob

On 7/10/15, 8:08 AM, "Ikrima Amaireh" <[email protected]> wrote:

Hi Robert,

My PC is running on Windows 7 Enterprise.
Initially, I installed Radiance for Window using its installer but
I found that most of the tutorials are provided for pc with Linux
and/or Linux-like operating systems; So I had to install try
learnix (that did not work) and Ubuntu (also did not work)!
Finally, I tried to use Cygwin to run Radiance on Window OS. I
could install Cygwin (works fine), Xming (not sure if working) and
Radiance (not all its programs are working!).

I'm a bit confused as I'm not sure if running Radiance on windows
using Cygwin will be enough for carrying my work. For example, can
I work out phases methods and generate BSDF data?

I wish if you can help me to do that.

Many thanks
ikrima

------------------------------

Message: 3
Date: Thu, 9 Jul 2015 16:44:49 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
        <[email protected]>
Subject: Re: [Radiance-general] Could not install Radiance!!!
Message-ID: <D1C400AC.1ADAC%[email protected]>
Content-Type: text/plain; charset="us-ascii"

Hi Ikrima,

We'll need a bit more info, here. What OS are you on? How are you
attempting to install it (using an installer, compiling from
source, or what)? What happens when you try??

On 7/9/15, 10:38 AM, "Ikrima Amaireh" <[email protected]> wrote:

Hi all,

After one a few weeks of trying, I could not manage to install
radiance properly. I am almost disappointed! Please any help?

Regards
Ikrima

This message and any attachment are intended solely for the
addressee and may contain confidential information. If you have
received this message in error, please send it back to me, and

immediately delete it.

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attachment may still contain software viruses which could damage
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------------------------------

Message: 3
Date: Fri, 10 Jul 2015 17:34:30 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
          <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] Modelling CFS
Message-ID:
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D697763F9F216044A99BC674C00561961358CA9BAF@EXCHANGE1.ad.nottingham.ac.
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Hi all,

Thanks Robert and Larrain for your detailed replies, that helped me
a lot.

I would summarise here what I got form your appreciated replies, as
following:
- Radiance is convenient and best of tools to model daylighting due
to its ray-tracing method.
- 3 or 5-phases methods are used to facilitate the calculations.
- Generating BSDF data is also used to facilitate these
calculations but it is limited to Klems resolution of some CFS.

Initially, I'm not planning to do annual calculations. It's just
for specific hours of the day and the target is to produce a
illuminance levels for indoor grid under different CFSs. Hence,
according to my understanding from Larrain words, I can use either
2-phase or Ray-tracing methods. My question is how can I
draw/define the CFS geometry and Space for these calculations? Is
it similar to the way use in Ecotect/Radiance calculations?

Regards
Ikrima

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Sent: 09 July 2015 19:56
To: [email protected]
Subject: Radiance-general Digest, Vol 137, Issue 8

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Today's Topics:

     1. CFS with Radiance (Ikrima Amaireh)
     2. Could not install Radiance!!! (Ikrima Amaireh)
     3. Re: Could not install Radiance!!! (Guglielmetti, Robert)
     4. Re: CFS with Radiance (Guglielmetti, Robert)
     5. Re: CFS with Radiance (Germ?n Molina Larrain)

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Message: 1
Date: Thu, 9 Jul 2015 17:26:29 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
          <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] CFS with Radiance
Message-ID:
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D697763F9F216044A99BC674C00561961358CA9710@EXCHANGE1.ad.nottingham.ac.
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Hi G. Larrain,

Thanks for your detailed clarification (below).

I wonder if you kindly can help me toward better understanding and
answering the following:

We agreed that for daylight modelling of spaces with CFS, Radiance
is a suitable tool as it applies ray-tracing method. And for annual
and/or climate-based daylight calculations, as calculation time
becomes a critical factor, using BSDF data for CFS is highly
recommended to tackle the task with radiance (using phases methods).
However:

- if someone needs to perform daylight calculations for given space
with different CFS (different cases for comparison purposes) to get
illumination levels for horizontal grid points (and not pictures
nor scenes), is Radiance still the most convenient option?
- is it still needed to use any of the phase methods (2, 3 or 5)?
- most importantly, is it still needed to get BSDF data for CFS or
just can model the detailed CFS in Radiance (and, if yes, how?)

Many thanks for your kind help :slight_smile:

Regards
Ikrima

"Ikrima,

I am going to try to build the puzzle of CFS, Phases, BSDF and
calculations.... at least the way I understand it.

*CFS* are those systems that, via interreflection or other light
transport phenomena, redirect light (or solar radiation). Thus, in
order to get a reliable result you will have to consider all the
phenomena involved.
Then, *common
simple performance indexes*, such as the miss-used Shading
Coefficient and the Aperture Percentage, *always loose a lot of
information, trying to reduce all the complex behavior of a CFS to
one single number*. We all know that venetian blinds are more
"transparent" from certain viewing directions than from others,
but these performance indexes do not tell you that.

Now... Radiance can certainly perform calculations of spaces with
CFS using its "common" Ray-tracing. However, this may be slow for
some purposes (i.e.
annual simulations and climate-based daylight modelling), and *this
is why 2, 3 and 5 phase methods have been developed*. The *BSDF*
representation, I would say, goes in the same direction... It allow
summarizing all the bounces, reflections, refractions, etc. that
occure withing the CFS in a single matrix or tensor.* By using
BSDFs*, Radiance itself and other tools (i.e. EnergyPlus) can treat
CFS as blackboxes, avoiding all the opcits within the system. A
BSDF that uses the Klems Full representation has
21,045 numbers (instead of one, such as the Shading Coefficient).

Being said all that, I would not trust a calculation method unless
it can actually deal with the optics of a CFS that is drawn and/or
it can use BSDF (or similar) information.

Lets remember that a perforated screen, a venetian blind, a light
diffusing device can all have a Shading Coefficient of 50%, but all
of them will behave very differently. I made some presentations
about this on my previous work (we sold complex Shading Devices),
trying to promote the use of BSDF in EnergyPlus calculations... the
differences (in solar heat gains) were more than considerable.

I hope that someone else gives us his/her perspective on this topic...
there are a lot of concepts that I might be misunderstanding.

Best!"

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Message: 2
Date: Thu, 9 Jul 2015 17:38:41 +0100
From: Ikrima Amaireh <[email protected]>
To: "[email protected]"
          <[email protected]>
Cc: Ikrima Amaireh <[email protected]>
Subject: [Radiance-general] Could not install Radiance!!!
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D697763F9F216044A99BC674C00561961358CA9719@EXCHANGE1.ad.nottingham.ac.
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Hi all,

After one a few weeks of trying, I could not manage to install
radiance properly. I am almost disappointed! Please any help?

Regards
Ikrima

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Message: 3
Date: Thu, 9 Jul 2015 16:44:49 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
          <[email protected]>
Subject: Re: [Radiance-general] Could not install Radiance!!!
Message-ID: <D1C400AC.1ADAC%[email protected]>
Content-Type: text/plain; charset="us-ascii"

Hi Ikrima,

We'll need a bit more info, here. What OS are you on? How are you
attempting to install it (using an installer, compiling from
source, or what)? What happens when you try??

On 7/9/15, 10:38 AM, "Ikrima Amaireh" <[email protected]> wrote:

Hi all,

After one a few weeks of trying, I could not manage to install
radiance properly. I am almost disappointed! Please any help?

Regards
Ikrima

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immediately delete it.

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Message: 4
Date: Thu, 9 Jul 2015 17:29:39 +0000
From: "Guglielmetti, Robert" <[email protected]>
To: "[email protected]"
          <[email protected]>
Subject: Re: [Radiance-general] CFS with Radiance
Message-ID: <D1C40477.1ADCA%[email protected]>
Content-Type: text/plain; charset="us-ascii"

Some very quick replies and clarifications within:

On 7/9/15, 10:26 AM, "Ikrima Amaireh" <[email protected]> wrote:

Hi G. Larrain,

Thanks for your detailed clarification (below).

I wonder if you kindly can help me toward better understanding and
answering the following:

We agreed that for daylight modelling of spaces with CFS, Radiance
is a suitable tool as it applies ray-tracing method. And for
annual and/or climate-based daylight calculations, as calculation
time becomes a critical factor, using BSDF data for CFS is highly
recommended to tackle the task with radiance (using phases methods).

However:

BSDF data in an annual simulation context is generally limited to
Klems basis BSDF data, which may not be high enough resolution for
some CFS. And the 5-phase method, which can circumvent this, is not
necessarily "quick".
This is all still very much a quandary and the newest daylight
metrics have added confusion to all of this, IMO.

- if someone needs to perform daylight calculations for given
space with different CFS (different cases for comparison purposes)
to get illumination levels for horizontal grid points (and not
pictures nor scenes), is Radiance still the most convenient option?

Absolutely. The lack of an image-as-output requirement does not
change the fact that ray tracing is a good/convenient algorithm
option for daylight simulation problems, especially when dealing
with diffusing media and CFS in general. BSDFs allow you to do
lots of "what-ifs", relatively quickly, but are beholden to the
limitations of the resolution of the BSDF.

- is it still needed to use any of the phase methods (2, 3 or 5)?

Is what still needed? BSDF data? Ray tracing? I don't know of other
lighting simulation tools that can employ the multiphase methods. I
would say BSDF data is optional for 2-phase, required for 3-phase,
and optional for 5-phase.

- most importantly, is it still needed to get BSDF data for CFS or
just can model the detailed CFS in Radiance (and, if yes, how?)

Again I'm confused as to what "it" is. A couple of approaches are
available to you in general. If you have a geometric model of the
CFS you can use Radiance (genBSDF) to make a BSDF of the CFS and
use that in a 3- or 5-phase context. However in an
annual/climate-based simulation context, you will be stuck with a
Klems basis BSDF and that will not be very good resolution for a
lot of CFS; here you may want to use the 5-phase method and stick
the actual CFS geometry in the building model.

Some things to consider here are the photon map, now a part of
Radiance proper, or using the 2-phase method where appropriate. By
2-phase method I mean generating a daylight matrix for your
calculation points (or view), and modeling the window material as-is.
If the "CFS" is a shade cloth, you can approximate that with a
Radiance "trans". Same for translucent panels.
With this single daylight matrix, you can throw a vector of sky
matrices at it and get an annual climate-based result very quickly.
Problem is, we want to do stuff to the windows, sometimes at the
time step level, so:

Blinds and compact daylight redirection devices (e.g. Lightlouver)
are best represented as BSDF, and if most of the redirected flux
is headed up and away from the points of interest, a Klems basis
BSDF is good enough IMO. In these cases you could use the 3-phase method.
Problem is when you have a BSDF for blinds, and you also want to
simulate the blinds-up condition (i.e. clear, specularly
transmitting glass). Using a Klems basis BSDF for this is
sub-optimal. You end up needing to do two annual simulations, one
as 2-phase for the clear glass scenario, and again as a 3-phase
(with a blinds BSDF for the transmission
matrix) for the blinds down condition. If you have a lot of
different window groups, your simulation space can get large in a
hurry. But it's still do-able and you can get results that tell a
story you simply couldn't tell 5 years ago, informing the newest
daylight metrics as well.

------------------------------

Message: 5
Date: Thu, 9 Jul 2015 15:56:11 -0300
From: Germ?n Molina Larrain <[email protected]>
To: Radiance general discussion
<[email protected]>
Subject: Re: [Radiance-general] CFS with Radiance
Message-ID:
          <CAF-iH4LSr=y12F1khTrHh6hnf-kS=EmaFuo8uWKvHqMs=
[email protected]>
Content-Type: text/plain; charset="utf-8"

I must say that I agree with Rob, however, a short answer that
might help.

For evaluating illuminance levels in a space with different CFS
you, strictly speaking, DO NOT HAVE TO do anything. You may choose
between different methods that have some pros and cons.

*ray-tracing*

     - Requires ray-tracing for each time-step and each system,
which is slow
     (*four systems simulated annualy in an hourly basis --> 4*8760

35,040
     simulations*.)
     - As accurate as it gets, if options are defined correctly.

*2 phase method*

     - Do not need the BSDF
     - Requires ray-tracing for each CFS (*4 systems --> 4 ray-tracing
     simulations*)
     - After ray-tracing, annual simulation is fast.

*3-phase method:*

     - Requires BSDF data in KLEMS basis, which may be slow to compute,
     unless it can be exported from WINDOW, for example, or such data has
     already been calculated (the idea is to make a database, I think).
     - Does not really work well for specular systems (Klems patches
are too
     big)
     - Requires 2 ray-tracing runs, always (*4 systems --> 2 ray-tracing
     simulations*)
     - After ray-tracing and BSDF calculation, annual simulation is
fast

*5-phase method:*

     - Requires BSDF data in KLEMS basis AND/OR Tensor tree format,
which
     may be slow to compute, unless it can be exported from WINDOW,
for example,
     or such data has already been calculated (the idea is to make a
database, I
     think).
     - Works well for specular systems
     - Requires 4 ray-tracing runs + 1 for each system, always (*4
systems
     --> 4+1 = 5 ray-tracing simulations*)
     - Hard to code...?
     - After ray-tracing and BSDF calculation, annual simulation is
fast

I would not say there is a recipe. If you have to choose between 1
or
2 CFSs, maybe it is faster to just draw them and use the 2 phase
method (or ray-tracing if an annual simulaton is not required). On
the contrary, if you are going to test 10 different CFSs, 3 and 5
phases may make sense, since you reduce the expensive ray-tracing
calculations... However, this will also depend on weather you have
the BSDF data AND/OR if it makes sense to calculate it and store it
AND/OR if you intend to simulate a dynamically controlled CFS.

Best!

2015-07-09 14:29 GMT-03:00 Guglielmetti, Robert <
[email protected]>:

Some very quick replies and clarifications within:

On 7/9/15, 10:26 AM, "Ikrima Amaireh" <[email protected]> wrote:

Hi G. Larrain,

Thanks for your detailed clarification (below).

I wonder if you kindly can help me toward better understanding
and answering the following:

We agreed that for daylight modelling of spaces with CFS,
Radiance is a suitable tool as it applies ray-tracing method. And
for annual and/or climate-based daylight calculations, as
calculation time becomes a critical factor, using BSDF data for
CFS is highly recommended to tackle the task with radiance (using phases methods).

However:

BSDF data in an annual simulation context is generally limited to
Klems basis BSDF data, which may not be high enough resolution for
some CFS. And the 5-phase method, which can circumvent this, is
not

necessarily "quick".

This is all still very much a quandary and the newest daylight
metrics have added confusion to all of this, IMO.

- if someone needs to perform daylight calculations for given
space with different CFS (different cases for comparison
purposes) to get illumination levels for horizontal grid points
(and not pictures nor scenes), is Radiance still the most convenient option?

Absolutely. The lack of an image-as-output requirement does not
change the fact that ray tracing is a good/convenient algorithm
option for daylight simulation problems, especially when dealing
with diffusing media and CFS in general. BSDFs allow you to do
lots of "what-ifs", relatively quickly, but are beholden to the
limitations of the

resolution of the BSDF.

- is it still needed to use any of the phase methods (2, 3 or 5)?

Is what still needed? BSDF data? Ray tracing? I don't know of
other lighting simulation tools that can employ the multiphase
methods. I would say BSDF data is optional for 2-phase, required
for 3-phase, and optional for 5-phase.

- most importantly, is it still needed to get BSDF data for CFS
or just can model the detailed CFS in Radiance (and, if yes,
how?)

Again I'm confused as to what "it" is. A couple of approaches are
available to you in general. If you have a geometric model of the
CFS you can use Radiance (genBSDF) to make a BSDF of the CFS and
use that in a 3- or 5-phase context. However in an
annual/climate-based simulation context, you will be stuck with a
Klems basis BSDF and that will not be very good resolution for a
lot of CFS; here you may want to use the 5-phase method and stick
the actual CFS geometry in the

building model.

Some things to consider here are the photon map, now a part of
Radiance proper, or using the 2-phase method where appropriate. By
2-phase method I mean generating a daylight matrix for your
calculation points (or view), and modeling the window material as-is.
If the "CFS" is a shade cloth, you can approximate that with a
Radiance

"trans". Same for translucent panels.

With this single daylight matrix, you can throw a vector of sky
matrices at it and get an annual climate-based result very quickly.
Problem is, we want to do stuff to the windows, sometimes at the
time

step level, so:

Blinds and compact daylight redirection devices (e.g. Lightlouver)
are best represented as BSDF, and if most of the redirected flux
is headed up and away from the points of interest, a Klems basis
BSDF is good enough IMO. In these cases you could use the 3-phase method.
Problem is when you have a BSDF for blinds, and you also want to
simulate the blinds-up condition (i.e. clear, specularly
transmitting glass). Using a Klems basis BSDF for this is
sub-optimal. You end up needing to do two annual simulations, one
as 2-phase for the clear glass scenario, and again as a 3-phase
(with a blinds BSDF for the transmission
matrix) for the blinds down condition. If you have a lot of
different window groups, your simulation space can get large in a
hurry. But it's still do-able and you can get results that tell a
story you simply couldn't tell 5 years ago, informing the newest
daylight metrics

as well.

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Radiance-general mailing list
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http://www.radiance-online.org/mailman/listinfo/radiance-general

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