Luminaire modelling using Radiance

German_Molina · August 7, 2015, 6:09pm

Hello everyone,

I think this might be a silly question, but I actually have not found too
much information on how to model luminaires using Radiance... I am asking
this because I want to add this feature to the plugin I am developing.

What is the recommended method for modelling luminaires in Radiance? I
intend to use IES files as input. Hopefully I would also have the geometry,
but I have to consider cases when this is not available.

I know there is an IES2RAD program, but I am not quite sure how general it
is. Also, I have heard about the use of illums (a sphere, for example) that
covers the entire luminaire....?

I am kind of lost, so if someone could give me a hint, I would really
appreciate it.

Also, if someone know where to find information about IES files and their
format, that would also be really helpful.

THANKS

Germán

Christopher_Rush · August 7, 2015, 7:14pm

Germán,

Appendix A and Appendix B of this linked document are excellent reference for the file format of IES and Elumdat files:

One of things you’ll see is that the IES file includes a crude dimensional information for the X Y and Z size of the luminaire. Negative numbers in the file can be used to indicate if a dimension indicates a dimension of a round rather than rectangular shape. In manufacturer IES data the geometric information is often missing altogether, Z dimension is omitted for recessed luminaires, or the X and Y dimensions are in the wrong places in relation to the photometric distribution.

If you use the IES2RAD command it will produce a geometric definition of the luminaire based purely on the X Y Z dimension definition in the IES file. So it’s best to correct the dimensions by editing the IES file with a text editor prior to running IES2RAD. Otherwise once you run IES2RAD it’s easier to make a mistake if you scale the fixture geometry and scale the intensity accordingly after the conversion.

-Chris

···

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Thomas_Bleicher2 · August 8, 2015, 2:46pm

Hi German.

The most important information you need you will find in the ies2rad man
page. In general you use it to create a library of luminaire *.rad and
*.dat files which you can later reference into your scenes via xform. I
found it more convenient and flexible for my exporters to create files with
triangular markers and use "!replmarks ..." to place multiple luminaire
files. That way you can later replace all luminaires in an array with a
single change in the scene file.

When you write a plugin you have to pay attention to the units of the ies
file and adjust the -d parameter accordingly. Unfortunately ies2rad doesn't
read that information from the file.

The geometry in IES files is limited to discs, ovals, rectangles and
extrusions of these shapes. Mostly you will find the 2 dimensional shapes
for recessed and spot lights while the 3 dimensional shapes are used for
pendants (boxes and cylinders). If you want to avoid these crude things in
your model and use detailed geometry instead (from a dxf file, for example)
then you use the -i option to create an illum sphere. The sphere will be
used with the luminance data generated from the ies file. You have to place
the detailed geometry of fixture into the sphere yourself. ies2rad doesn't
do that for you.

I found that geometry provided by manufacturers is very detailed and can
lead to problems in large models. MGF geometry information is extremely
rare.

You can use the -t option to set the lamp type. This defines the color
temperature. The -m option allows you to set a maintenance factor that all
artificial lighting calculations require. Not that some lamp type entries
in the lamp.tab file already include a correction factor for the lamp so
you have to take this into account when calculating the final value of -m.
I found it safest to use "-t WHITE" (which does not have a correction) and
lump all the efficiency reductions and maintenance factors together into a
single -m value.

European manufacturers provide are more likely to provide Eulumdat file
specs for their luminairs. Sometimes they convert these for you into IES
files. If you can only get LDT files you can use DIALUX or something
similar to convert the LDT to IES files. It used to offer this option a few
year ago, at least. There may be other converters out there, but I don't
remember the names.

Hth, Thomas

···

On Fri, Aug 7, 2015 at 2:09 PM, Germán Molina Larrain <[email protected]> wrote:

Hello everyone,

I think this might be a silly question, but I actually have not found too
much information on how to model luminaires using Radiance... I am asking
this because I want to add this feature to the plugin I am developing.

What is the recommended method for modelling luminaires in Radiance? I
intend to use IES files as input. Hopefully I would also have the geometry,
but I have to consider cases when this is not available.

I know there is an IES2RAD program, but I am not quite sure how general it
is. Also, I have heard about the use of illums (a sphere, for example) that
covers the entire luminaire....?

I am kind of lost, so if someone could give me a hint, I would really
appreciate it.

Also, if someone know where to find information about IES files and their
format, that would also be really helpful.

THANKS

Germán

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

Randolph_Fritz4 · August 8, 2015, 8:31pm

The basic technique is to wrap the visible geometry of the luminaire, if
any, with a glow in a simple shape that actually radiates the light. The
glow is transparent, so that the geometry can be seen, and direct
illumination does not pass through the glow, so light can be used internal
to the glow to give the luminaire a realistic look.

The glow geometry and description may be generated by ies2rad. IIRC only
four shapes are supported: sphere, rectangular, cuboid (box), and thin disc.

Ies2rad does not support eulumdat and again, IIRC, has not been updated to
support the latest IES photometry standard, LM-63-02.

···

--
Randolph M. Fritz, Lighting Design and Simulation
+1 206 390 4477 || [email protected]

On Sat, Aug 8, 2015 at 7:46 AM, Thomas Bleicher <[email protected]> wrote:

Hi German.

The most important information you need you will find in the ies2rad man
page. In general you use it to create a library of luminaire *.rad and

*.dat

files which you can later reference into your scenes via xform. I found it
more convenient and flexible for my exporters to create files with
triangular markers and use "!replmarks ..." to place multiple luminaire
files. That way you can later replace all luminaires in an array with a
single change in the scene file.

When you write a plugin you have to pay attention to the units of the ies
file and adjust the -d parameter accordingly. Unfortunately ies2rad

doesn't

read that information from the file.

The geometry in IES files is limited to discs, ovals, rectangles and
extrusions of these shapes. Mostly you will find the 2 dimensional shapes
for recessed and spot lights while the 3 dimensional shapes are used for
pendants (boxes and cylinders). If you want to avoid these crude things in
your model and use detailed geometry instead (from a dxf file, for

example)

then you use the -i option to create an illum sphere. The sphere will be
used with the luminance data generated from the ies file. You have to

place

the detailed geometry of fixture into the sphere yourself. ies2rad doesn't
do that for you.

I found that geometry provided by manufacturers is very detailed and can
lead to problems in large models. MGF geometry information is extremely
rare.

You can use the -t option to set the lamp type. This defines the color
temperature. The -m option allows you to set a maintenance factor that all
artificial lighting calculations require. Not that some lamp type entries

in

the lamp.tab file already include a correction factor for the lamp so you
have to take this into account when calculating the final value of -m. I
found it safest to use "-t WHITE" (which does not have a correction) and
lump all the efficiency reductions and maintenance factors together into a
single -m value.

European manufacturers provide are more likely to provide Eulumdat file
specs for their luminairs. Sometimes they convert these for you into IES
files. If you can only get LDT files you can use DIALUX or something

similar

to convert the LDT to IES files. It used to offer this option a few year
ago, at least. There may be other converters out there, but I don't

remember

the names.

Hth, Thomas

On Fri, Aug 7, 2015 at 2:09 PM, Germán Molina Larrain < [email protected]> > wrote:

Hello everyone,

I think this might be a silly question, but I actually have not found too
much information on how to model luminaires using Radiance... I am asking
this because I want to add this feature to the plugin I am developing.

What is the recommended method for modelling luminaires in Radiance? I
intend to use IES files as input. Hopefully I would also have the

geometry,

but I have to consider cases when this is not available.

I know there is an IES2RAD program, but I am not quite sure how general

it

is. Also, I have heard about the use of illums (a sphere, for example)

that

covers the entire luminaire....?

I am kind of lost, so if someone could give me a hint, I would really
appreciate it.

Also, if someone know where to find information about IES files and their
format, that would also be really helpful.

THANKS

Germán

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

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

Rob_Guglielmetti · August 8, 2015, 8:59pm

Thomas has great info on lamp color and using replmarks. Further to Randolph’s post, the idea is to wrap the luminaire geometry as tightly as possible using the shapes Randolph mentioned, but this enveloping geometry will have *illum* applied to it, not glow. The glow is used to illuminate the luminaire geometry itself so that it appears realistic in a rendering. You apply glows to the lamp objects in the luminaire generally, or you could apply them to any shades or lenses in the luminaire.

The luminous intensity of the illum is derived from the input lumens in the IES file and is modulated by a few cal files, which use the candela values from the IES file. The lamp color utility can give you reasonable values to use for the glows, based on lamp input lumens. Again, the glows illuminate the local luminaire geometry, and the illums actually illuminate the space. The ileum material is invisible when viewed directly, which is why you need the glows to make the luminaries appear correct in a rendering. The flux from the glow also does not make it past the illum geometry and so it does not contribute to the scene illumination or any calculations.

There is some info on using illums and glows here:

http://www.rumblestrip.org/using-the-illum-material-for-smoother-renderings-in-radiance/

I did a bunch of crap with different illum geometry and cal files (lboxcorr.cal et al.) and got pretty good at picking the best ones for the jobs at hand (wall mounted sconces and stuff like that can be tricky to get looking “right”), but never got around to posting a summary on that stuff. A good place to start is just running a few different luminaire types though ies2rad and see what you get, and then play with the output files from there.

Are we having fun yet?

-Rob

···

From: Randolph M. Fritz <[email protected]>
Reply: Radiance general discussion <[email protected]>>
Date: August 8, 2015 at 2:32:01 PM
To: Radiance general discussion <[email protected]>>
Subject: Re: [Radiance-general] Luminaire modelling using Radiance

The basic technique is to wrap the visible geometry of the luminaire, if any, with a glow in a simple shape that actually radiates the light. The glow is transparent, so that the geometry can be seen, and direct illumination does not pass through the glow, so light can be used internal to the glow to give the luminaire a realistic look.

The glow geometry and description may be generated by ies2rad. IIRC only four shapes are supported: sphere, rectangular, cuboid (box), and thin disc.

Ies2rad does not support eulumdat and again, IIRC, has not been updated to support the latest IES photometry standard, LM-63-02.

--
Randolph M. Fritz, Lighting Design and Simulation
+1 206 390 4477 || [email protected]

On Sat, Aug 8, 2015 at 7:46 AM, Thomas Bleicher <[email protected]> wrote:

Hi German.

The most important information you need you will find in the ies2rad man
page. In general you use it to create a library of luminaire *.rad and *.dat
files which you can later reference into your scenes via xform. I found it
more convenient and flexible for my exporters to create files with
triangular markers and use "!replmarks ..." to place multiple luminaire
files. That way you can later replace all luminaires in an array with a
single change in the scene file.

When you write a plugin you have to pay attention to the units of the ies
file and adjust the -d parameter accordingly. Unfortunately ies2rad doesn't
read that information from the file.

The geometry in IES files is limited to discs, ovals, rectangles and
extrusions of these shapes. Mostly you will find the 2 dimensional shapes
for recessed and spot lights while the 3 dimensional shapes are used for
pendants (boxes and cylinders). If you want to avoid these crude things in
your model and use detailed geometry instead (from a dxf file, for example)
then you use the -i option to create an illum sphere. The sphere will be
used with the luminance data generated from the ies file. You have to place
the detailed geometry of fixture into the sphere yourself. ies2rad doesn't
do that for you.

I found that geometry provided by manufacturers is very detailed and can
lead to problems in large models. MGF geometry information is extremely
rare.

You can use the -t option to set the lamp type. This defines the color
temperature. The -m option allows you to set a maintenance factor that all
artificial lighting calculations require. Not that some lamp type entries in
the lamp.tab file already include a correction factor for the lamp so you
have to take this into account when calculating the final value of -m. I
found it safest to use "-t WHITE" (which does not have a correction) and
lump all the efficiency reductions and maintenance factors together into a
single -m value.

European manufacturers provide are more likely to provide Eulumdat file
specs for their luminairs. Sometimes they convert these for you into IES
files. If you can only get LDT files you can use DIALUX or something similar
to convert the LDT to IES files. It used to offer this option a few year
ago, at least. There may be other converters out there, but I don't remember
the names.

Hth, Thomas

On Fri, Aug 7, 2015 at 2:09 PM, Germán Molina Larrain <[email protected]> > wrote:

Hello everyone,

I think this might be a silly question, but I actually have not found too
much information on how to model luminaires using Radiance... I am asking
this because I want to add this feature to the plugin I am developing.

What is the recommended method for modelling luminaires in Radiance? I
intend to use IES files as input. Hopefully I would also have the geometry,
but I have to consider cases when this is not available.

I know there is an IES2RAD program, but I am not quite sure how general it
is. Also, I have heard about the use of illums (a sphere, for example) that
covers the entire luminaire....?

I am kind of lost, so if someone could give me a hint, I would really
appreciate it.

Also, if someone know where to find information about IES files and their
format, that would also be really helpful.

THANKS

Germán

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

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

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

Randolph_Fritz4 · August 8, 2015, 10:52pm

"Further to Randolph’s post, the idea is to wrap the luminaire
geometry as tightly as possible using the shapes Randolph mentioned,
but this enveloping geometry will have *illum* applied to it, not
glow"

Duh. Rob is, of course, quite correct.

···

--
Randolph M. Fritz, Lighting Design and Simulation
+1 206 390 4477 || [email protected]

On Sat, Aug 8, 2015 at 1:59 PM, Rob Guglielmetti <[email protected]> wrote:

Thomas has great info on lamp color and using replmarks. Further to
Randolph’s post, the idea is to wrap the luminaire geometry as tightly as
possible using the shapes Randolph mentioned, but this enveloping geometry
will have *illum* applied to it, not glow. The glow is used to illuminate
the luminaire geometry itself so that it appears realistic in a rendering.
You apply glows to the lamp objects in the luminaire generally, or you could
apply them to any shades or lenses in the luminaire.

The luminous intensity of the illum is derived from the input lumens in the
IES file and is modulated by a few cal files, which use the candela values
from the IES file. The lamp color utility can give you reasonable values to
use for the glows, based on lamp input lumens. Again, the glows illuminate
the local luminaire geometry, and the illums actually illuminate the space.
The ileum material is invisible when viewed directly, which is why you need
the glows to make the luminaries appear correct in a rendering. The flux
from the glow also does not make it past the illum geometry and so it does
not contribute to the scene illumination or any calculations.

There is some info on using illums and glows here:

http://www.rumblestrip.org/using-the-illum-material-for-smoother-renderings-in-radiance/

I did a bunch of crap with different illum geometry and cal files
(lboxcorr.cal et al.) and got pretty good at picking the best ones for the
jobs at hand (wall mounted sconces and stuff like that can be tricky to get
looking “right”), but never got around to posting a summary on that stuff. A
good place to start is just running a few different luminaire types though
ies2rad and see what you get, and then play with the output files from
there.

Are we having fun yet?

-Rob

From: Randolph M. Fritz <[email protected]>
Reply: Radiance general discussion <[email protected]>>
Date: August 8, 2015 at 2:32:01 PM
To: Radiance general discussion <[email protected]>>
Subject: Re: [Radiance-general] Luminaire modelling using Radiance

The basic technique is to wrap the visible geometry of the luminaire, if
any, with a glow in a simple shape that actually radiates the light. The
glow is transparent, so that the geometry can be seen, and direct
illumination does not pass through the glow, so light can be used internal
to the glow to give the luminaire a realistic look.

The glow geometry and description may be generated by ies2rad. IIRC only
four shapes are supported: sphere, rectangular, cuboid (box), and thin disc.

Ies2rad does not support eulumdat and again, IIRC, has not been updated to
support the latest IES photometry standard, LM-63-02.

--
Randolph M. Fritz, Lighting Design and Simulation
+1 206 390 4477 || [email protected]

On Sat, Aug 8, 2015 at 7:46 AM, Thomas Bleicher <[email protected]> wrote:

Hi German.

The most important information you need you will find in the ies2rad man
page. In general you use it to create a library of luminaire *.rad and
*.dat
files which you can later reference into your scenes via xform. I found it
more convenient and flexible for my exporters to create files with
triangular markers and use "!replmarks ..." to place multiple luminaire
files. That way you can later replace all luminaires in an array with a
single change in the scene file.

When you write a plugin you have to pay attention to the units of the ies
file and adjust the -d parameter accordingly. Unfortunately ies2rad
doesn't
read that information from the file.

The geometry in IES files is limited to discs, ovals, rectangles and
extrusions of these shapes. Mostly you will find the 2 dimensional shapes
for recessed and spot lights while the 3 dimensional shapes are used for
pendants (boxes and cylinders). If you want to avoid these crude things in
your model and use detailed geometry instead (from a dxf file, for
example)
then you use the -i option to create an illum sphere. The sphere will be
used with the luminance data generated from the ies file. You have to
place
the detailed geometry of fixture into the sphere yourself. ies2rad doesn't
do that for you.

I found that geometry provided by manufacturers is very detailed and can
lead to problems in large models. MGF geometry information is extremely
rare.

You can use the -t option to set the lamp type. This defines the color
temperature. The -m option allows you to set a maintenance factor that all
artificial lighting calculations require. Not that some lamp type entries
in
the lamp.tab file already include a correction factor for the lamp so you
have to take this into account when calculating the final value of -m. I
found it safest to use "-t WHITE" (which does not have a correction) and
lump all the efficiency reductions and maintenance factors together into a
single -m value.

European manufacturers provide are more likely to provide Eulumdat file
specs for their luminairs. Sometimes they convert these for you into IES
files. If you can only get LDT files you can use DIALUX or something
similar
to convert the LDT to IES files. It used to offer this option a few year
ago, at least. There may be other converters out there, but I don't
remember
the names.

Hth, Thomas

On Fri, Aug 7, 2015 at 2:09 PM, Germán Molina Larrain >> <[email protected]> >> wrote:

Hello everyone,

I think this might be a silly question, but I actually have not found too
much information on how to model luminaires using Radiance... I am asking
this because I want to add this feature to the plugin I am developing.

What is the recommended method for modelling luminaires in Radiance? I
intend to use IES files as input. Hopefully I would also have the
geometry,
but I have to consider cases when this is not available.

I know there is an IES2RAD program, but I am not quite sure how general
it
is. Also, I have heard about the use of illums (a sphere, for example)
that
covers the entire luminaire....?

I am kind of lost, so if someone could give me a hint, I would really
appreciate it.

Also, if someone know where to find information about IES files and their
format, that would also be really helpful.

THANKS

Germán

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

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

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

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

German_Molina · August 10, 2015, 1:24pm

well, thanks a lot guys! I have a lot to read, write, try and see now.... I
will let you guys know how this goes and come back with a lot of new
questions, haha.

Best,

Germán

···

2015-08-08 19:52 GMT-03:00 Randolph M. Fritz <[email protected]>:

"Further to Randolph’s post, the idea is to wrap the luminaire
geometry as tightly as possible using the shapes Randolph mentioned,
but this enveloping geometry will have *illum* applied to it, not
glow"

Duh. Rob is, of course, quite correct.
--
Randolph M. Fritz, Lighting Design and Simulation
+1 206 390 4477 || [email protected]

On Sat, Aug 8, 2015 at 1:59 PM, Rob Guglielmetti > <[email protected]> wrote:
> Thomas has great info on lamp color and using replmarks. Further to
> Randolph’s post, the idea is to wrap the luminaire geometry as tightly as
> possible using the shapes Randolph mentioned, but this enveloping
geometry
> will have *illum* applied to it, not glow. The glow is used to illuminate
> the luminaire geometry itself so that it appears realistic in a
rendering.
> You apply glows to the lamp objects in the luminaire generally, or you
could
> apply them to any shades or lenses in the luminaire.
>
> The luminous intensity of the illum is derived from the input lumens in
the
> IES file and is modulated by a few cal files, which use the candela
values
> from the IES file. The lamp color utility can give you reasonable values
to
> use for the glows, based on lamp input lumens. Again, the glows
illuminate
> the local luminaire geometry, and the illums actually illuminate the
space.
> The ileum material is invisible when viewed directly, which is why you
need
> the glows to make the luminaries appear correct in a rendering. The flux
> from the glow also does not make it past the illum geometry and so it
does
> not contribute to the scene illumination or any calculations.
>
> There is some info on using illums and glows here:
>
>
http://www.rumblestrip.org/using-the-illum-material-for-smoother-renderings-in-radiance/
>
> I did a bunch of crap with different illum geometry and cal files
> (lboxcorr.cal et al.) and got pretty good at picking the best ones for
the
> jobs at hand (wall mounted sconces and stuff like that can be tricky to
get
> looking “right”), but never got around to posting a summary on that
stuff. A
> good place to start is just running a few different luminaire types
though
> ies2rad and see what you get, and then play with the output files from
> there.
>
> Are we having fun yet?
>
> -Rob
>
> From: Randolph M. Fritz <[email protected]>
> Reply: Radiance general discussion <[email protected]
>>
> Date: August 8, 2015 at 2:32:01 PM
> To: Radiance general discussion <[email protected]>>
> Subject: Re: [Radiance-general] Luminaire modelling using Radiance
>
> The basic technique is to wrap the visible geometry of the luminaire, if
> any, with a glow in a simple shape that actually radiates the light. The
> glow is transparent, so that the geometry can be seen, and direct
> illumination does not pass through the glow, so light can be used
internal
> to the glow to give the luminaire a realistic look.
>
> The glow geometry and description may be generated by ies2rad. IIRC only
> four shapes are supported: sphere, rectangular, cuboid (box), and thin
disc.
>
> Ies2rad does not support eulumdat and again, IIRC, has not been updated
to
> support the latest IES photometry standard, LM-63-02.
>
> --
> Randolph M. Fritz, Lighting Design and Simulation
> +1 206 390 4477 || [email protected]
>
> On Sat, Aug 8, 2015 at 7:46 AM, Thomas Bleicher <[email protected]> > wrote:
>> Hi German.
>>
>> The most important information you need you will find in the ies2rad man
>> page. In general you use it to create a library of luminaire *.rad and
>> *.dat
>> files which you can later reference into your scenes via xform. I found
it
>> more convenient and flexible for my exporters to create files with
>> triangular markers and use "!replmarks ..." to place multiple luminaire
>> files. That way you can later replace all luminaires in an array with a
>> single change in the scene file.
>>
>> When you write a plugin you have to pay attention to the units of the
ies
>> file and adjust the -d parameter accordingly. Unfortunately ies2rad
>> doesn't
>> read that information from the file.
>>
>> The geometry in IES files is limited to discs, ovals, rectangles and
>> extrusions of these shapes. Mostly you will find the 2 dimensional
shapes
>> for recessed and spot lights while the 3 dimensional shapes are used for
>> pendants (boxes and cylinders). If you want to avoid these crude things
in
>> your model and use detailed geometry instead (from a dxf file, for
>> example)
>> then you use the -i option to create an illum sphere. The sphere will be
>> used with the luminance data generated from the ies file. You have to
>> place
>> the detailed geometry of fixture into the sphere yourself. ies2rad
doesn't
>> do that for you.
>>
>> I found that geometry provided by manufacturers is very detailed and can
>> lead to problems in large models. MGF geometry information is extremely
>> rare.
>>
>> You can use the -t option to set the lamp type. This defines the color
>> temperature. The -m option allows you to set a maintenance factor that
all
>> artificial lighting calculations require. Not that some lamp type
entries
>> in
>> the lamp.tab file already include a correction factor for the lamp so
you
>> have to take this into account when calculating the final value of -m. I
>> found it safest to use "-t WHITE" (which does not have a correction) and
>> lump all the efficiency reductions and maintenance factors together
into a
>> single -m value.
>>
>> European manufacturers provide are more likely to provide Eulumdat file
>> specs for their luminairs. Sometimes they convert these for you into IES
>> files. If you can only get LDT files you can use DIALUX or something
>> similar
>> to convert the LDT to IES files. It used to offer this option a few year
>> ago, at least. There may be other converters out there, but I don't
>> remember
>> the names.
>>
>> Hth, Thomas
>>
>> On Fri, Aug 7, 2015 at 2:09 PM, Germán Molina Larrain > >> <[email protected]> > >> wrote:
>>>
>>> Hello everyone,
>>>
>>> I think this might be a silly question, but I actually have not found
too
>>> much information on how to model luminaires using Radiance... I am
asking
>>> this because I want to add this feature to the plugin I am developing.
>>>
>>> What is the recommended method for modelling luminaires in Radiance? I
>>> intend to use IES files as input. Hopefully I would also have the
>>> geometry,
>>> but I have to consider cases when this is not available.
>>>
>>> I know there is an IES2RAD program, but I am not quite sure how general
>>> it
>>> is. Also, I have heard about the use of illums (a sphere, for example)
>>> that
>>> covers the entire luminaire....?
>>>
>>> I am kind of lost, so if someone could give me a hint, I would really
>>> appreciate it.
>>>
>>> Also, if someone know where to find information about IES files and
their
>>> format, that would also be really helpful.
>>>
>>> THANKS
>>>
>>> Germán
>>>
>>> _______________________________________________
>>> Radiance-general mailing list
>>> [email protected]
>>> http://www.radiance-online.org/mailman/listinfo/radiance-general
>>>
>>
>>
>> _______________________________________________
>> Radiance-general mailing list
>> [email protected]
>> http://www.radiance-online.org/mailman/listinfo/radiance-general
>>
>
> _______________________________________________
> Radiance-general mailing list
> [email protected]
> http://www.radiance-online.org/mailman/listinfo/radiance-general
>
>
> _______________________________________________
> Radiance-general mailing list
> [email protected]
> http://www.radiance-online.org/mailman/listinfo/radiance-general
>

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

German_Molina · November 11, 2015, 7:29pm

Hello again guys,

I have a question now.... I have been reading about all this, and I would
like to input geometry surrounded by illum. However, ies2rad seem to only
be able to generate a Sphere. How do I try this with different shapes?
(i.e. a box) is it just a matter of deleting the Sphere and put a lot of
Polygons with the same modifier? I am worried about normals and stuff like
that.

I hope I made myself clear, haha

Regards,

Germán

···

2015-08-10 10:24 GMT-03:00 Germán Molina Larrain <[email protected]>:

well, thanks a lot guys! I have a lot to read, write, try and see now....
I will let you guys know how this goes and come back with a lot of new
questions, haha.

Best,

Germán

2015-08-08 19:52 GMT-03:00 Randolph M. Fritz <[email protected]>:

"Further to Randolph’s post, the idea is to wrap the luminaire
geometry as tightly as possible using the shapes Randolph mentioned,
but this enveloping geometry will have *illum* applied to it, not
glow"

Duh. Rob is, of course, quite correct.
--
Randolph M. Fritz, Lighting Design and Simulation
+1 206 390 4477 || [email protected]

On Sat, Aug 8, 2015 at 1:59 PM, Rob Guglielmetti >> <[email protected]> wrote:
> Thomas has great info on lamp color and using replmarks. Further to
> Randolph’s post, the idea is to wrap the luminaire geometry as tightly
as
> possible using the shapes Randolph mentioned, but this enveloping
geometry
> will have *illum* applied to it, not glow. The glow is used to
illuminate
> the luminaire geometry itself so that it appears realistic in a
rendering.
> You apply glows to the lamp objects in the luminaire generally, or you
could
> apply them to any shades or lenses in the luminaire.
>
> The luminous intensity of the illum is derived from the input lumens in
the
> IES file and is modulated by a few cal files, which use the candela
values
> from the IES file. The lamp color utility can give you reasonable
values to
> use for the glows, based on lamp input lumens. Again, the glows
illuminate
> the local luminaire geometry, and the illums actually illuminate the
space.
> The ileum material is invisible when viewed directly, which is why you
need
> the glows to make the luminaries appear correct in a rendering. The flux
> from the glow also does not make it past the illum geometry and so it
does
> not contribute to the scene illumination or any calculations.
>
> There is some info on using illums and glows here:
>
>
http://www.rumblestrip.org/using-the-illum-material-for-smoother-renderings-in-radiance/
>
> I did a bunch of crap with different illum geometry and cal files
> (lboxcorr.cal et al.) and got pretty good at picking the best ones for
the
> jobs at hand (wall mounted sconces and stuff like that can be tricky to
get
> looking “right”), but never got around to posting a summary on that
stuff. A
> good place to start is just running a few different luminaire types
though
> ies2rad and see what you get, and then play with the output files from
> there.
>
> Are we having fun yet?
>
> -Rob
>
> From: Randolph M. Fritz <[email protected]>
> Reply: Radiance general discussion <
[email protected]>>
> Date: August 8, 2015 at 2:32:01 PM
> To: Radiance general discussion <[email protected]>>
> Subject: Re: [Radiance-general] Luminaire modelling using Radiance
>
> The basic technique is to wrap the visible geometry of the luminaire, if
> any, with a glow in a simple shape that actually radiates the light. The
> glow is transparent, so that the geometry can be seen, and direct
> illumination does not pass through the glow, so light can be used
internal
> to the glow to give the luminaire a realistic look.
>
> The glow geometry and description may be generated by ies2rad. IIRC only
> four shapes are supported: sphere, rectangular, cuboid (box), and thin
disc.
>
> Ies2rad does not support eulumdat and again, IIRC, has not been updated
to
> support the latest IES photometry standard, LM-63-02.
>
> --
> Randolph M. Fritz, Lighting Design and Simulation
> +1 206 390 4477 || [email protected]
>
> On Sat, Aug 8, 2015 at 7:46 AM, Thomas Bleicher <[email protected]> >> wrote:
>> Hi German.
>>
>> The most important information you need you will find in the ies2rad
man
>> page. In general you use it to create a library of luminaire *.rad and
>> *.dat
>> files which you can later reference into your scenes via xform. I
found it
>> more convenient and flexible for my exporters to create files with
>> triangular markers and use "!replmarks ..." to place multiple luminaire
>> files. That way you can later replace all luminaires in an array with a
>> single change in the scene file.
>>
>> When you write a plugin you have to pay attention to the units of the
ies
>> file and adjust the -d parameter accordingly. Unfortunately ies2rad
>> doesn't
>> read that information from the file.
>>
>> The geometry in IES files is limited to discs, ovals, rectangles and
>> extrusions of these shapes. Mostly you will find the 2 dimensional
shapes
>> for recessed and spot lights while the 3 dimensional shapes are used
for
>> pendants (boxes and cylinders). If you want to avoid these crude
things in
>> your model and use detailed geometry instead (from a dxf file, for
>> example)
>> then you use the -i option to create an illum sphere. The sphere will
be
>> used with the luminance data generated from the ies file. You have to
>> place
>> the detailed geometry of fixture into the sphere yourself. ies2rad
doesn't
>> do that for you.
>>
>> I found that geometry provided by manufacturers is very detailed and
can
>> lead to problems in large models. MGF geometry information is extremely
>> rare.
>>
>> You can use the -t option to set the lamp type. This defines the color
>> temperature. The -m option allows you to set a maintenance factor that
all
>> artificial lighting calculations require. Not that some lamp type
entries
>> in
>> the lamp.tab file already include a correction factor for the lamp so
you
>> have to take this into account when calculating the final value of -m.
I
>> found it safest to use "-t WHITE" (which does not have a correction)
and
>> lump all the efficiency reductions and maintenance factors together
into a
>> single -m value.
>>
>> European manufacturers provide are more likely to provide Eulumdat file
>> specs for their luminairs. Sometimes they convert these for you into
IES
>> files. If you can only get LDT files you can use DIALUX or something
>> similar
>> to convert the LDT to IES files. It used to offer this option a few
year
>> ago, at least. There may be other converters out there, but I don't
>> remember
>> the names.
>>
>> Hth, Thomas
>>
>> On Fri, Aug 7, 2015 at 2:09 PM, Germán Molina Larrain >> >> <[email protected]> >> >> wrote:
>>>
>>> Hello everyone,
>>>
>>> I think this might be a silly question, but I actually have not found
too
>>> much information on how to model luminaires using Radiance... I am
asking
>>> this because I want to add this feature to the plugin I am developing.
>>>
>>> What is the recommended method for modelling luminaires in Radiance? I
>>> intend to use IES files as input. Hopefully I would also have the
>>> geometry,
>>> but I have to consider cases when this is not available.
>>>
>>> I know there is an IES2RAD program, but I am not quite sure how
general
>>> it
>>> is. Also, I have heard about the use of illums (a sphere, for example)
>>> that
>>> covers the entire luminaire....?
>>>
>>> I am kind of lost, so if someone could give me a hint, I would really
>>> appreciate it.
>>>
>>> Also, if someone know where to find information about IES files and
their
>>> format, that would also be really helpful.
>>>
>>> THANKS
>>>
>>> Germán
>>>
>>> _______________________________________________
>>> Radiance-general mailing list
>>> [email protected]
>>> http://www.radiance-online.org/mailman/listinfo/radiance-general
>>>
>>
>>
>> _______________________________________________
>> Radiance-general mailing list
>> [email protected]
>> http://www.radiance-online.org/mailman/listinfo/radiance-general
>>
>
> _______________________________________________
> Radiance-general mailing list
> [email protected]
> http://www.radiance-online.org/mailman/listinfo/radiance-general
>
>
> _______________________________________________
> Radiance-general mailing list
> [email protected]
> http://www.radiance-online.org/mailman/listinfo/radiance-general
>

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

Greg_Ward · November 11, 2015, 7:40pm

Hi Germán,

Yes, it is a little more complicated, and you are right to worry about normals! Actually, it is the projected area that matters, which for the sphere is (mostly) constant. The main thing you need to do is to compute a first real brightdata argument (A1) equal to the existing one produced by ies2rad, multiplied by PI*R*R, where R is the radius of the original sphere. Multiplying the value thus by the projected area of the emitter gets you back to radiant intensity. Then, use the "boxcorr" function as the first string argument to the brightdata primitive in order that this radiant intensity is divided by the projected area in the appropriate direction during rendering.

It would be prudent to verify the results by rendering illuminance in a large sphere around the light source before and after, just to make sure neither of us messed up!

Cheers,
-Greg

···

From: Germán Molina Larrain <[email protected]>
Subject: Re: [Radiance-general] Luminaire modelling using Radiance
Date: November 11, 2015 9:29:48 AM HST

Hello again guys,

I have a question now.... I have been reading about all this, and I would like to input geometry surrounded by illum. However, ies2rad seem to only be able to generate a Sphere. How do I try this with different shapes? (i.e. a box) is it just a matter of deleting the Sphere and put a lot of Polygons with the same modifier? I am worried about normals and stuff like that.

I hope I made myself clear, haha

Regards,

Germán

2015-08-10 10:24 GMT-03:00 Germán Molina Larrain <[email protected]>:
well, thanks a lot guys! I have a lot to read, write, try and see now.... I will let you guys know how this goes and come back with a lot of new questions, haha.

Best,

Germán

2015-08-08 19:52 GMT-03:00 Randolph M. Fritz <[email protected]>:
"Further to Randolph’s post, the idea is to wrap the luminaire
geometry as tightly as possible using the shapes Randolph mentioned,
but this enveloping geometry will have *illum* applied to it, not
glow"

Duh. Rob is, of course, quite correct.
--
Randolph M. Fritz, Lighting Design and Simulation
+1 206 390 4477 || [email protected]

On Sat, Aug 8, 2015 at 1:59 PM, Rob Guglielmetti > <[email protected]> wrote:
> Thomas has great info on lamp color and using replmarks. Further to
> Randolph’s post, the idea is to wrap the luminaire geometry as tightly as
> possible using the shapes Randolph mentioned, but this enveloping geometry
> will have *illum* applied to it, not glow. The glow is used to illuminate
> the luminaire geometry itself so that it appears realistic in a rendering.
> You apply glows to the lamp objects in the luminaire generally, or you could
> apply them to any shades or lenses in the luminaire.
>
> The luminous intensity of the illum is derived from the input lumens in the
> IES file and is modulated by a few cal files, which use the candela values
> from the IES file. The lamp color utility can give you reasonable values to
> use for the glows, based on lamp input lumens. Again, the glows illuminate
> the local luminaire geometry, and the illums actually illuminate the space.
> The ileum material is invisible when viewed directly, which is why you need
> the glows to make the luminaries appear correct in a rendering. The flux
> from the glow also does not make it past the illum geometry and so it does
> not contribute to the scene illumination or any calculations.
>
> There is some info on using illums and glows here:
>
> http://www.rumblestrip.org/using-the-illum-material-for-smoother-renderings-in-radiance/
>
> I did a bunch of crap with different illum geometry and cal files
> (lboxcorr.cal et al.) and got pretty good at picking the best ones for the
> jobs at hand (wall mounted sconces and stuff like that can be tricky to get
> looking “right”), but never got around to posting a summary on that stuff. A
> good place to start is just running a few different luminaire types though
> ies2rad and see what you get, and then play with the output files from
> there.
>
> Are we having fun yet?
>
> -Rob
>
> From: Randolph M. Fritz <[email protected]>
> Reply: Radiance general discussion <[email protected]>>
> Date: August 8, 2015 at 2:32:01 PM
> To: Radiance general discussion <[email protected]>>
> Subject: Re: [Radiance-general] Luminaire modelling using Radiance
>
> The basic technique is to wrap the visible geometry of the luminaire, if
> any, with a glow in a simple shape that actually radiates the light. The
> glow is transparent, so that the geometry can be seen, and direct
> illumination does not pass through the glow, so light can be used internal
> to the glow to give the luminaire a realistic look.
>
> The glow geometry and description may be generated by ies2rad. IIRC only
> four shapes are supported: sphere, rectangular, cuboid (box), and thin disc.
>
> Ies2rad does not support eulumdat and again, IIRC, has not been updated to
> support the latest IES photometry standard, LM-63-02.
>
> --
> Randolph M. Fritz, Lighting Design and Simulation
> +1 206 390 4477 || [email protected]
>
> On Sat, Aug 8, 2015 at 7:46 AM, Thomas Bleicher <[email protected]> wrote:
>> Hi German.
>>
>> The most important information you need you will find in the ies2rad man
>> page. In general you use it to create a library of luminaire *.rad and
>> *.dat
>> files which you can later reference into your scenes via xform. I found it
>> more convenient and flexible for my exporters to create files with
>> triangular markers and use "!replmarks ..." to place multiple luminaire
>> files. That way you can later replace all luminaires in an array with a
>> single change in the scene file.
>>
>> When you write a plugin you have to pay attention to the units of the ies
>> file and adjust the -d parameter accordingly. Unfortunately ies2rad
>> doesn't
>> read that information from the file.
>>
>> The geometry in IES files is limited to discs, ovals, rectangles and
>> extrusions of these shapes. Mostly you will find the 2 dimensional shapes
>> for recessed and spot lights while the 3 dimensional shapes are used for
>> pendants (boxes and cylinders). If you want to avoid these crude things in
>> your model and use detailed geometry instead (from a dxf file, for
>> example)
>> then you use the -i option to create an illum sphere. The sphere will be
>> used with the luminance data generated from the ies file. You have to
>> place
>> the detailed geometry of fixture into the sphere yourself. ies2rad doesn't
>> do that for you.
>>
>> I found that geometry provided by manufacturers is very detailed and can
>> lead to problems in large models. MGF geometry information is extremely
>> rare.
>>
>> You can use the -t option to set the lamp type. This defines the color
>> temperature. The -m option allows you to set a maintenance factor that all
>> artificial lighting calculations require. Not that some lamp type entries
>> in
>> the lamp.tab file already include a correction factor for the lamp so you
>> have to take this into account when calculating the final value of -m. I
>> found it safest to use "-t WHITE" (which does not have a correction) and
>> lump all the efficiency reductions and maintenance factors together into a
>> single -m value.
>>
>> European manufacturers provide are more likely to provide Eulumdat file
>> specs for their luminairs. Sometimes they convert these for you into IES
>> files. If you can only get LDT files you can use DIALUX or something
>> similar
>> to convert the LDT to IES files. It used to offer this option a few year
>> ago, at least. There may be other converters out there, but I don't
>> remember
>> the names.
>>
>> Hth, Thomas
>>
>> On Fri, Aug 7, 2015 at 2:09 PM, Germán Molina Larrain > >> <[email protected]> > >> wrote:
>>>
>>> Hello everyone,
>>>
>>> I think this might be a silly question, but I actually have not found too
>>> much information on how to model luminaires using Radiance... I am asking
>>> this because I want to add this feature to the plugin I am developing.
>>>
>>> What is the recommended method for modelling luminaires in Radiance? I
>>> intend to use IES files as input. Hopefully I would also have the
>>> geometry,
>>> but I have to consider cases when this is not available.
>>>
>>> I know there is an IES2RAD program, but I am not quite sure how general
>>> it
>>> is. Also, I have heard about the use of illums (a sphere, for example)
>>> that
>>> covers the entire luminaire....?
>>>
>>> I am kind of lost, so if someone could give me a hint, I would really
>>> appreciate it.
>>>
>>> Also, if someone know where to find information about IES files and their
>>> format, that would also be really helpful.
>>>
>>> THANKS
>>>
>>> Germán
>>>
>>> _______________________________________________
>>> Radiance-general mailing list
>>> [email protected]
>>> http://www.radiance-online.org/mailman/listinfo/radiance-general
>>>
>>
>>
>> _______________________________________________
>> Radiance-general mailing list
>> [email protected]
>> http://www.radiance-online.org/mailman/listinfo/radiance-general
>>
>
> _______________________________________________
> Radiance-general mailing list
> [email protected]
> http://www.radiance-online.org/mailman/listinfo/radiance-general
>
>
> _______________________________________________
> Radiance-general mailing list
> [email protected]
> http://www.radiance-online.org/mailman/listinfo/radiance-general
>

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

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

German_Molina · November 11, 2015, 8:56pm

Hi Greg,

Thanks very much for the information. I tried what you said, and I think
that you might be slightly wrong.

- At First I did what you said... multiplied the original A1 value in
brightdata (127.324) by Pi and by R2 (0.05*0.05) and the returned number
was ridiculously close to 1, which is the -m option I input.

- I checked the surce.cal file, and the boxcorr requires A1, A2, A3 and
A4... the first one being a multiplier and the others being the length,
width and depth of the box. Using A1...A4 = 1 0.1 0.1 0.1, I got the
following results

TOP VIEW <https://drive.google.com/file/d/0B2NfkTSl19hQVkdzN1JlWFllcE0/view>
BOTTOM VIEW
<https://drive.google.com/file/d/0B2NfkTSl19hQVXRvTXRWYV9hR2s/view?usp=sharing>

One of them is using just ies2rad , the second is using ies2rad -i 0.05 and
the third one is transforming this to a box as explained before.... *THEY
LOOK GOOD TO ME...?*

I think the area and that kind of things has to be used for planar
surfaces. right? I mean, for when we do crazier boxes...?

Regards,

Germán

···

2015-11-11 16:40 GMT-03:00 Greg Ward <[email protected]>:

Hi Germán,

Yes, it is a little more complicated, and you are right to worry about
normals! Actually, it is the projected area that matters, which for the
sphere is (mostly) constant. The main thing you need to do is to compute a
first real brightdata argument (A1) equal to the existing one produced by
ies2rad, multiplied by PI*R*R, where R is the radius of the original
sphere. Multiplying the value thus by the projected area of the emitter
gets you back to radiant intensity. Then, use the "boxcorr" function as
the first string argument to the brightdata primitive in order that this
radiant intensity is divided by the projected area in the appropriate
direction during rendering.

It would be prudent to verify the results by rendering illuminance in a
large sphere around the light source before and after, just to make sure
neither of us messed up!

Cheers,
-Greg

*From: *Germán Molina Larrain <[email protected]>

*Subject: *Re: [Radiance-general] Luminaire modelling using Radiance

*Date: *November 11, 2015 9:29:48 AM HST

Hello again guys,

I have a question now.... I have been reading about all this, and I would
like to input geometry surrounded by illum. However, ies2rad seem to only
be able to generate a Sphere. How do I try this with different shapes?
(i.e. a box) is it just a matter of deleting the Sphere and put a lot of
Polygons with the same modifier? I am worried about normals and stuff like
that.

I hope I made myself clear, haha

Regards,

Germán

2015-08-10 10:24 GMT-03:00 Germán Molina Larrain <[email protected]>:

well, thanks a lot guys! I have a lot to read, write, try and see now....
I will let you guys know how this goes and come back with a lot of new
questions, haha.

Best,

Germán

2015-08-08 19:52 GMT-03:00 Randolph M. Fritz <[email protected]>:

"Further to Randolph’s post, the idea is to wrap the luminaire
geometry as tightly as possible using the shapes Randolph mentioned,
but this enveloping geometry will have *illum* applied to it, not
glow"

Duh. Rob is, of course, quite correct.
--
Randolph M. Fritz, Lighting Design and Simulation
+1 206 390 4477 || [email protected]

On Sat, Aug 8, 2015 at 1:59 PM, Rob Guglielmetti >>> <[email protected]> wrote:
> Thomas has great info on lamp color and using replmarks. Further to
> Randolph’s post, the idea is to wrap the luminaire geometry as tightly
as
> possible using the shapes Randolph mentioned, but this enveloping
geometry
> will have *illum* applied to it, not glow. The glow is used to
illuminate
> the luminaire geometry itself so that it appears realistic in a
rendering.
> You apply glows to the lamp objects in the luminaire generally, or you
could
> apply them to any shades or lenses in the luminaire.
>
> The luminous intensity of the illum is derived from the input lumens
in the
> IES file and is modulated by a few cal files, which use the candela
values
> from the IES file. The lamp color utility can give you reasonable
values to
> use for the glows, based on lamp input lumens. Again, the glows
illuminate
> the local luminaire geometry, and the illums actually illuminate the
space.
> The ileum material is invisible when viewed directly, which is why you
need
> the glows to make the luminaries appear correct in a rendering. The
flux
> from the glow also does not make it past the illum geometry and so it
does
> not contribute to the scene illumination or any calculations.
>
> There is some info on using illums and glows here:
>
>
http://www.rumblestrip.org/using-the-illum-material-for-smoother-renderings-in-radiance/
>
> I did a bunch of crap with different illum geometry and cal files
> (lboxcorr.cal et al.) and got pretty good at picking the best ones for
the
> jobs at hand (wall mounted sconces and stuff like that can be tricky
to get
> looking “right”), but never got around to posting a summary on that
stuff. A
> good place to start is just running a few different luminaire types
though
> ies2rad and see what you get, and then play with the output files from
> there.
>
> Are we having fun yet?
>
> -Rob
>
> From: Randolph M. Fritz <[email protected]>
> Reply: Radiance general discussion <
[email protected]>>
> Date: August 8, 2015 at 2:32:01 PM
> To: Radiance general discussion <[email protected]
>>
> Subject: Re: [Radiance-general] Luminaire modelling using Radiance
>
> The basic technique is to wrap the visible geometry of the luminaire,
if
> any, with a glow in a simple shape that actually radiates the light.
The
> glow is transparent, so that the geometry can be seen, and direct
> illumination does not pass through the glow, so light can be used
internal
> to the glow to give the luminaire a realistic look.
>
> The glow geometry and description may be generated by ies2rad. IIRC
only
> four shapes are supported: sphere, rectangular, cuboid (box), and thin
disc.
>
> Ies2rad does not support eulumdat and again, IIRC, has not been
updated to
> support the latest IES photometry standard, LM-63-02.
>
> --
> Randolph M. Fritz, Lighting Design and Simulation
> +1 206 390 4477 || [email protected]
>
> On Sat, Aug 8, 2015 at 7:46 AM, Thomas Bleicher <[email protected]> >>> wrote:
>> Hi German.
>>
>> The most important information you need you will find in the ies2rad
man
>> page. In general you use it to create a library of luminaire *.rad and
>> *.dat
>> files which you can later reference into your scenes via xform. I
found it
>> more convenient and flexible for my exporters to create files with
>> triangular markers and use "!replmarks ..." to place multiple
luminaire
>> files. That way you can later replace all luminaires in an array with
a
>> single change in the scene file.
>>
>> When you write a plugin you have to pay attention to the units of the
ies
>> file and adjust the -d parameter accordingly. Unfortunately ies2rad
>> doesn't
>> read that information from the file.
>>
>> The geometry in IES files is limited to discs, ovals, rectangles and
>> extrusions of these shapes. Mostly you will find the 2 dimensional
shapes
>> for recessed and spot lights while the 3 dimensional shapes are used
for
>> pendants (boxes and cylinders). If you want to avoid these crude
things in
>> your model and use detailed geometry instead (from a dxf file, for
>> example)
>> then you use the -i option to create an illum sphere. The sphere will
be
>> used with the luminance data generated from the ies file. You have to
>> place
>> the detailed geometry of fixture into the sphere yourself. ies2rad
doesn't
>> do that for you.
>>
>> I found that geometry provided by manufacturers is very detailed and
can
>> lead to problems in large models. MGF geometry information is
extremely
>> rare.
>>
>> You can use the -t option to set the lamp type. This defines the color
>> temperature. The -m option allows you to set a maintenance factor
that all
>> artificial lighting calculations require. Not that some lamp type
entries
>> in
>> the lamp.tab file already include a correction factor for the lamp so
you
>> have to take this into account when calculating the final value of
-m. I
>> found it safest to use "-t WHITE" (which does not have a correction)
and
>> lump all the efficiency reductions and maintenance factors together
into a
>> single -m value.
>>
>> European manufacturers provide are more likely to provide Eulumdat
file
>> specs for their luminairs. Sometimes they convert these for you into
IES
>> files. If you can only get LDT files you can use DIALUX or something
>> similar
>> to convert the LDT to IES files. It used to offer this option a few
year
>> ago, at least. There may be other converters out there, but I don't
>> remember
>> the names.
>>
>> Hth, Thomas
>>
>> On Fri, Aug 7, 2015 at 2:09 PM, Germán Molina Larrain >>> >> <[email protected]> >>> >> wrote:
>>>
>>> Hello everyone,
>>>
>>> I think this might be a silly question, but I actually have not
found too
>>> much information on how to model luminaires using Radiance... I am
asking
>>> this because I want to add this feature to the plugin I am
developing.
>>>
>>> What is the recommended method for modelling luminaires in Radiance?
I
>>> intend to use IES files as input. Hopefully I would also have the
>>> geometry,
>>> but I have to consider cases when this is not available.
>>>
>>> I know there is an IES2RAD program, but I am not quite sure how
general
>>> it
>>> is. Also, I have heard about the use of illums (a sphere, for
example)
>>> that
>>> covers the entire luminaire....?
>>>
>>> I am kind of lost, so if someone could give me a hint, I would really
>>> appreciate it.
>>>
>>> Also, if someone know where to find information about IES files and
their
>>> format, that would also be really helpful.
>>>
>>> THANKS
>>>
>>> Germán
>>>
>>> _______________________________________________
>>> Radiance-general mailing list
>>> [email protected]
>>> http://www.radiance-online.org/mailman/listinfo/radiance-general
>>>
>>
>>
>> _______________________________________________
>> Radiance-general mailing list
>> [email protected]
>> http://www.radiance-online.org/mailman/listinfo/radiance-general
>>
>
> _______________________________________________
> Radiance-general mailing list
> [email protected]
> http://www.radiance-online.org/mailman/listinfo/radiance-general
>
>
> _______________________________________________
> Radiance-general mailing list
> [email protected]
> http://www.radiance-online.org/mailman/listinfo/radiance-general
>

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

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

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

German_Molina · November 11, 2015, 9:07pm

In the end, this is the illum modifier... *I wonder about the src_theta *
parameter

void brightdata noGeo_illum_dist
4 boxcorr noGeo_illum.dat source.cal src_theta
0
4 1 0.1 0.1 0.1 # 1, dimx, dimy, dimz

···

2015-11-11 17:56 GMT-03:00 Germán Molina Larrain <[email protected]>:

Hi Greg,

Thanks very much for the information. I tried what you said, and I think
that you might be slightly wrong.

- At First I did what you said... multiplied the original A1 value in
brightdata (127.324) by Pi and by R2 (0.05*0.05) and the returned number
was ridiculously close to 1, which is the -m option I input.

- I checked the surce.cal file, and the boxcorr requires A1, A2, A3 and
A4... the first one being a multiplier and the others being the length,
width and depth of the box. Using A1...A4 = 1 0.1 0.1 0.1, I got the
following results

TOP VIEW
<https://drive.google.com/file/d/0B2NfkTSl19hQVkdzN1JlWFllcE0/view>
BOTTOM VIEW
<https://drive.google.com/file/d/0B2NfkTSl19hQVXRvTXRWYV9hR2s/view?usp=sharing>

One of them is using just ies2rad , the second is using ies2rad -i 0.05
and the third one is transforming this to a box as explained before.... *THEY
LOOK GOOD TO ME...?*

I think the area and that kind of things has to be used for planar
surfaces. right? I mean, for when we do crazier boxes...?

Regards,

Germán

2015-11-11 16:40 GMT-03:00 Greg Ward <[email protected]>:

Hi Germán,

Yes, it is a little more complicated, and you are right to worry about
normals! Actually, it is the projected area that matters, which for the
sphere is (mostly) constant. The main thing you need to do is to compute a
first real brightdata argument (A1) equal to the existing one produced by
ies2rad, multiplied by PI*R*R, where R is the radius of the original
sphere. Multiplying the value thus by the projected area of the emitter
gets you back to radiant intensity. Then, use the "boxcorr" function as
the first string argument to the brightdata primitive in order that this
radiant intensity is divided by the projected area in the appropriate
direction during rendering.

It would be prudent to verify the results by rendering illuminance in a
large sphere around the light source before and after, just to make sure
neither of us messed up!

Cheers,
-Greg

*From: *Germán Molina Larrain <[email protected]>

*Subject: *Re: [Radiance-general] Luminaire modelling using Radiance

*Date: *November 11, 2015 9:29:48 AM HST

Hello again guys,

I have a question now.... I have been reading about all this, and I would
like to input geometry surrounded by illum. However, ies2rad seem to only
be able to generate a Sphere. How do I try this with different shapes?
(i.e. a box) is it just a matter of deleting the Sphere and put a lot of
Polygons with the same modifier? I am worried about normals and stuff like
that.

I hope I made myself clear, haha

Regards,

Germán

2015-08-10 10:24 GMT-03:00 Germán Molina Larrain <[email protected]>:

well, thanks a lot guys! I have a lot to read, write, try and see
now.... I will let you guys know how this goes and come back with a lot of
new questions, haha.

Best,

Germán

2015-08-08 19:52 GMT-03:00 Randolph M. Fritz <[email protected]>:

"Further to Randolph’s post, the idea is to wrap the luminaire
geometry as tightly as possible using the shapes Randolph mentioned,
but this enveloping geometry will have *illum* applied to it, not
glow"

Duh. Rob is, of course, quite correct.
--
Randolph M. Fritz, Lighting Design and Simulation
+1 206 390 4477 || [email protected]

On Sat, Aug 8, 2015 at 1:59 PM, Rob Guglielmetti >>>> <[email protected]> wrote:
> Thomas has great info on lamp color and using replmarks. Further to
> Randolph’s post, the idea is to wrap the luminaire geometry as
tightly as
> possible using the shapes Randolph mentioned, but this enveloping
geometry
> will have *illum* applied to it, not glow. The glow is used to
illuminate
> the luminaire geometry itself so that it appears realistic in a
rendering.
> You apply glows to the lamp objects in the luminaire generally, or
you could
> apply them to any shades or lenses in the luminaire.
>
> The luminous intensity of the illum is derived from the input lumens
in the
> IES file and is modulated by a few cal files, which use the candela
values
> from the IES file. The lamp color utility can give you reasonable
values to
> use for the glows, based on lamp input lumens. Again, the glows
illuminate
> the local luminaire geometry, and the illums actually illuminate the
space.
> The ileum material is invisible when viewed directly, which is why
you need
> the glows to make the luminaries appear correct in a rendering. The
flux
> from the glow also does not make it past the illum geometry and so it
does
> not contribute to the scene illumination or any calculations.
>
> There is some info on using illums and glows here:
>
>
http://www.rumblestrip.org/using-the-illum-material-for-smoother-renderings-in-radiance/
>
> I did a bunch of crap with different illum geometry and cal files
> (lboxcorr.cal et al.) and got pretty good at picking the best ones
for the
> jobs at hand (wall mounted sconces and stuff like that can be tricky
to get
> looking “right”), but never got around to posting a summary on that
stuff. A
> good place to start is just running a few different luminaire types
though
> ies2rad and see what you get, and then play with the output files from
> there.
>
> Are we having fun yet?
>
> -Rob
>
> From: Randolph M. Fritz <[email protected]>
> Reply: Radiance general discussion <
[email protected]>>
> Date: August 8, 2015 at 2:32:01 PM
> To: Radiance general discussion <[email protected]
>>
> Subject: Re: [Radiance-general] Luminaire modelling using Radiance
>
> The basic technique is to wrap the visible geometry of the luminaire,
if
> any, with a glow in a simple shape that actually radiates the light.
The
> glow is transparent, so that the geometry can be seen, and direct
> illumination does not pass through the glow, so light can be used
internal
> to the glow to give the luminaire a realistic look.
>
> The glow geometry and description may be generated by ies2rad. IIRC
only
> four shapes are supported: sphere, rectangular, cuboid (box), and
thin disc.
>
> Ies2rad does not support eulumdat and again, IIRC, has not been
updated to
> support the latest IES photometry standard, LM-63-02.
>
> --
> Randolph M. Fritz, Lighting Design and Simulation
> +1 206 390 4477 || [email protected]
>
> On Sat, Aug 8, 2015 at 7:46 AM, Thomas Bleicher <[email protected]> >>>> wrote:
>> Hi German.
>>
>> The most important information you need you will find in the ies2rad
man
>> page. In general you use it to create a library of luminaire *.rad
and
>> *.dat
>> files which you can later reference into your scenes via xform. I
found it
>> more convenient and flexible for my exporters to create files with
>> triangular markers and use "!replmarks ..." to place multiple
luminaire
>> files. That way you can later replace all luminaires in an array
with a
>> single change in the scene file.
>>
>> When you write a plugin you have to pay attention to the units of
the ies
>> file and adjust the -d parameter accordingly. Unfortunately ies2rad
>> doesn't
>> read that information from the file.
>>
>> The geometry in IES files is limited to discs, ovals, rectangles and
>> extrusions of these shapes. Mostly you will find the 2 dimensional
shapes
>> for recessed and spot lights while the 3 dimensional shapes are used
for
>> pendants (boxes and cylinders). If you want to avoid these crude
things in
>> your model and use detailed geometry instead (from a dxf file, for
>> example)
>> then you use the -i option to create an illum sphere. The sphere
will be
>> used with the luminance data generated from the ies file. You have to
>> place
>> the detailed geometry of fixture into the sphere yourself. ies2rad
doesn't
>> do that for you.
>>
>> I found that geometry provided by manufacturers is very detailed and
can
>> lead to problems in large models. MGF geometry information is
extremely
>> rare.
>>
>> You can use the -t option to set the lamp type. This defines the
color
>> temperature. The -m option allows you to set a maintenance factor
that all
>> artificial lighting calculations require. Not that some lamp type
entries
>> in
>> the lamp.tab file already include a correction factor for the lamp
so you
>> have to take this into account when calculating the final value of
-m. I
>> found it safest to use "-t WHITE" (which does not have a correction)
and
>> lump all the efficiency reductions and maintenance factors together
into a
>> single -m value.
>>
>> European manufacturers provide are more likely to provide Eulumdat
file
>> specs for their luminairs. Sometimes they convert these for you into
IES
>> files. If you can only get LDT files you can use DIALUX or something
>> similar
>> to convert the LDT to IES files. It used to offer this option a few
year
>> ago, at least. There may be other converters out there, but I don't
>> remember
>> the names.
>>
>> Hth, Thomas
>>
>> On Fri, Aug 7, 2015 at 2:09 PM, Germán Molina Larrain >>>> >> <[email protected]> >>>> >> wrote:
>>>
>>> Hello everyone,
>>>
>>> I think this might be a silly question, but I actually have not
found too
>>> much information on how to model luminaires using Radiance... I am
asking
>>> this because I want to add this feature to the plugin I am
developing.
>>>
>>> What is the recommended method for modelling luminaires in
Radiance? I
>>> intend to use IES files as input. Hopefully I would also have the
>>> geometry,
>>> but I have to consider cases when this is not available.
>>>
>>> I know there is an IES2RAD program, but I am not quite sure how
general
>>> it
>>> is. Also, I have heard about the use of illums (a sphere, for
example)
>>> that
>>> covers the entire luminaire....?
>>>
>>> I am kind of lost, so if someone could give me a hint, I would
really
>>> appreciate it.
>>>
>>> Also, if someone know where to find information about IES files and
their
>>> format, that would also be really helpful.
>>>
>>> THANKS
>>>
>>> Germán
>>>
>>> _______________________________________________
>>> Radiance-general mailing list
>>> [email protected]
>>> http://www.radiance-online.org/mailman/listinfo/radiance-general
>>>
>>
>>
>> _______________________________________________
>> Radiance-general mailing list
>> [email protected]
>> http://www.radiance-online.org/mailman/listinfo/radiance-general
>>
>
> _______________________________________________
> Radiance-general mailing list
> [email protected]
> http://www.radiance-online.org/mailman/listinfo/radiance-general
>
>
> _______________________________________________
> Radiance-general mailing list
> [email protected]
> http://www.radiance-online.org/mailman/listinfo/radiance-general
>

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

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

_______________________________________________
Radiance-general mailing list
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Jack_de_Valpine · November 11, 2015, 10:12pm

Hi Germ�n,

I am following this somewhat peripherally, however I do note that from the appearance of your test samples, in the bottom view, the right most sample looks different. The higher end (the yellow portion) is smaller than in the other two samples...

-Jack

···

On 11/11/2015 4:07 PM, Germ�n Molina Larrain wrote:

In the end, this is the illum modifier... *I wonder about the src_theta *parameter

void brightdata noGeo_illum_dist
4 boxcorr noGeo_illum.dat source.cal src_theta
0
4 1 0.1 0.1 0.1 # 1, dimx, dimy, dimz

2015-11-11 17:56 GMT-03:00 Germ�n Molina Larrain <[email protected] <mailto:[email protected]>>:

    Hi Greg,

    Thanks very much for the information. I tried what you said, and I
    think that you might be slightly wrong.

    - At First I did what you said... multiplied the original A1 value
    in brightdata (127.324) by Pi and by R2 (0.05*0.05) and the
    returned number was ridiculously close to 1, which is the -m
    option I input.

    - I checked the surce.cal file, and the boxcorr requires A1, A2,
    A3 and A4... the first one being a multiplier and the others being
    the length, width and depth of the box. Using A1...A4 = 1 0.1 0.1
    0.1, I got the following results

    TOP VIEW
    <https://drive.google.com/file/d/0B2NfkTSl19hQVkdzN1JlWFllcE0/view>
    BOTTOM VIEW
    <https://drive.google.com/file/d/0B2NfkTSl19hQVXRvTXRWYV9hR2s/view?usp=sharing>

    One of them is using just ies2rad , the second is using ies2rad -i
    0.05 and the third one is transforming this to a box as explained
    before.... *THEY LOOK GOOD TO ME...?*

    I think the area and that kind of things has to be used for planar
    surfaces. right? I mean, for when we do crazier boxes...?

    Regards,

    Germ�n

    2015-11-11 16:40 GMT-03:00 Greg Ward <[email protected]
    <mailto:[email protected]>>:

        Hi Germ�n,

        Yes, it is a little more complicated, and you are right to
        worry about normals! Actually, it is the projected area that
        matters, which for the sphere is (mostly) constant. The main
        thing you need to do is to compute a first real brightdata
        argument (A1) equal to the existing one produced by ies2rad,
        multiplied by PI*R*R, where R is the radius of the original
        sphere. Multiplying the value thus by the projected area of
        the emitter gets you back to radiant intensity. Then, use the
        "boxcorr" function as the first string argument to the
        brightdata primitive in order that this radiant intensity is
        divided by the projected area in the appropriate direction
        during rendering.

        It would be prudent to verify the results by rendering
        illuminance in a large sphere around the light source before
        and after, just to make sure neither of us messed up!

        Cheers,
        -Greg

        *From: *Germ�n Molina Larrain <[email protected]
        <mailto:[email protected]>>

        *Subject: *Re: [Radiance-general] Luminaire modelling using
        Radiance

        *Date: *November 11, 2015 9:29:48 AM HST

        *

        Hello again guys,

        I have a question now.... I have been reading about all this,
        and I would like to input geometry surrounded by illum.
        However, ies2rad seem to only be able to generate a Sphere.
        How do I try this with different shapes? (i.e. a box) is it
        just a matter of deleting the Sphere and put a lot of
        Polygons with the same modifier? I am worried about normals
        and stuff like that.

        I hope I made myself clear, haha

        Regards,

        Germ�n

        2015-08-10 10:24 GMT-03:00 Germ�n Molina Larrain
        <[email protected] <mailto:[email protected]>>:

            well, thanks a lot guys! I have a lot to read, write, try
            and see now.... I will let you guys know how this goes
            and come back with a lot of new questions, haha.

            Best,

            Germ�n

            2015-08-08 19:52 GMT-03:00 Randolph M. Fritz
            <[email protected] <mailto:[email protected]>>:

                "Further to Randolph�s post, the idea is to wrap the
                luminaire
                geometry as tightly as possible using the shapes
                Randolph mentioned,
                but this enveloping geometry will have *illum*
                applied to it, not
                glow"

                Duh. Rob is, of course, quite correct.
                --
                Randolph M. Fritz, Lighting Design and Simulation
                +1 206 390 4477 <tel:%2B1%20206%20390%204477> ||
                [email protected] <mailto:[email protected]>

                On Sat, Aug 8, 2015 at 1:59 PM, Rob Guglielmetti >> <[email protected] >> <mailto:[email protected]>> wrote:
                > Thomas has great info on lamp color and using
                replmarks. Further to
                > Randolph�s post, the idea is to wrap the luminaire
                geometry as tightly as
                > possible using the shapes Randolph mentioned, but
                this enveloping geometry
                > will have *illum* applied to it, not glow. The glow
                is used to illuminate
                > the luminaire geometry itself so that it appears
                realistic in a rendering.
                > You apply glows to the lamp objects in the
                luminaire generally, or you could
                > apply them to any shades or lenses in the luminaire.
                >
                > The luminous intensity of the illum is derived from
                the input lumens in the
                > IES file and is modulated by a few cal files, which
                use the candela values
                > from the IES file. The lamp color utility can give
                you reasonable values to
                > use for the glows, based on lamp input lumens.
                Again, the glows illuminate
                > the local luminaire geometry, and the illums
                actually illuminate the space.
                > The ileum material is invisible when viewed
                directly, which is why you need
                > the glows to make the luminaries appear correct in
                a rendering. The flux
                > from the glow also does not make it past the illum
                geometry and so it does
                > not contribute to the scene illumination or any
                calculations.
                >
                > There is some info on using illums and glows here:
                >
                http://www.rumblestrip.org/using-the-illum-material-for-smoother-renderings-in-radiance/
                >
                > I did a bunch of crap with different illum geometry
                and cal files
                > (lboxcorr.cal et al.) and got pretty good at
                picking the best ones for the
                > jobs at hand (wall mounted sconces and stuff like
                that can be tricky to get
                > looking �right�), but never got around to posting a
                summary on that stuff. A
                > good place to start is just running a few different
                luminaire types though
                > ies2rad and see what you get, and then play with
                the output files from
                > there.
                >
                > Are we having fun yet?
                >
                > -Rob
                >
                > From: Randolph M. Fritz <[email protected]
                <mailto:[email protected]>>
                > Reply: Radiance general discussion
                <[email protected]
                <mailto:[email protected]>>>
                > Date: August 8, 2015 at 2:32:01 PM
                > To: Radiance general discussion
                <[email protected]
                <mailto:[email protected]>>>
                > Subject: Re: [Radiance-general] Luminaire
                modelling using Radiance
                >
                > The basic technique is to wrap the visible geometry
                of the luminaire, if
                > any, with a glow in a simple shape that actually
                radiates the light. The
                > glow is transparent, so that the geometry can be
                seen, and direct
                > illumination does not pass through the glow, so
                light can be used internal
                > to the glow to give the luminaire a realistic look.
                >
                > The glow geometry and description may be generated
                by ies2rad. IIRC only
                > four shapes are supported: sphere, rectangular,
                cuboid (box), and thin disc.
                >
                > Ies2rad does not support eulumdat and again, IIRC,
                has not been updated to
                > support the latest IES photometry standard, LM-63-02.
                >
                > --
                > Randolph M. Fritz, Lighting Design and Simulation
                > +1 206 390 4477 <tel:%2B1%20206%20390%204477> ||
                [email protected] <mailto:[email protected]>
                >
                > On Sat, Aug 8, 2015 at 7:46 AM, Thomas Bleicher >> <[email protected] <mailto:[email protected]>> wrote:
                >> Hi German.
                >>
                >> The most important information you need you will
                find in the ies2rad man
                >> page. In general you use it to create a library of
                luminaire *.rad and
                >> *.dat
                >> files which you can later reference into your
                scenes via xform. I found it
                >> more convenient and flexible for my exporters to
                create files with
                >> triangular markers and use "!replmarks ..." to
                place multiple luminaire
                >> files. That way you can later replace all
                luminaires in an array with a
                >> single change in the scene file.
                >>
                >> When you write a plugin you have to pay attention
                to the units of the ies
                >> file and adjust the -d parameter accordingly.
                Unfortunately ies2rad
                >> doesn't
                >> read that information from the file.
                >>
                >> The geometry in IES files is limited to discs,
                ovals, rectangles and
                >> extrusions of these shapes. Mostly you will find
                the 2 dimensional shapes
                >> for recessed and spot lights while the 3
                dimensional shapes are used for
                >> pendants (boxes and cylinders). If you want to
                avoid these crude things in
                >> your model and use detailed geometry instead (from
                a dxf file, for
                >> example)
                >> then you use the -i option to create an illum
                sphere. The sphere will be
                >> used with the luminance data generated from the
                ies file. You have to
                >> place
                >> the detailed geometry of fixture into the sphere
                yourself. ies2rad doesn't
                >> do that for you.
                >>
                >> I found that geometry provided by manufacturers is
                very detailed and can
                >> lead to problems in large models. MGF geometry
                information is extremely
                >> rare.
                >>
                >> You can use the -t option to set the lamp type.
                This defines the color
                >> temperature. The -m option allows you to set a
                maintenance factor that all
                >> artificial lighting calculations require. Not that
                some lamp type entries
                >> in
                >> the lamp.tab file already include a correction
                factor for the lamp so you
                >> have to take this into account when calculating
                the final value of -m. I
                >> found it safest to use "-t WHITE" (which does not
                have a correction) and
                >> lump all the efficiency reductions and maintenance
                factors together into a
                >> single -m value.
                >>
                >> European manufacturers provide are more likely to
                provide Eulumdat file
                >> specs for their luminairs. Sometimes they convert
                these for you into IES
                >> files. If you can only get LDT files you can use
                DIALUX or something
                >> similar
                >> to convert the LDT to IES files. It used to offer
                this option a few year
                >> ago, at least. There may be other converters out
                there, but I don't
                >> remember
                >> the names.
                >>
                >> Hth, Thomas
                >>
                >> On Fri, Aug 7, 2015 at 2:09 PM, Germ�n Molina Larrain >> >> <[email protected] <mailto:[email protected]>> >> >> wrote:
                >>>
                >>> Hello everyone,
                >>>
                >>> I think this might be a silly question, but I
                actually have not found too
                >>> much information on how to model luminaires using
                Radiance... I am asking
                >>> this because I want to add this feature to the
                plugin I am developing.
                >>>
                >>> What is the recommended method for modelling
                luminaires in Radiance? I
                >>> intend to use IES files as input. Hopefully I
                would also have the
                >>> geometry,
                >>> but I have to consider cases when this is not
                available.
                >>>
                >>> I know there is an IES2RAD program, but I am not
                quite sure how general
                >>> it
                >>> is. Also, I have heard about the use of illums (a
                sphere, for example)
                >>> that
                >>> covers the entire luminaire....?
                >>>
                >>> I am kind of lost, so if someone could give me a
                hint, I would really
                >>> appreciate it.
                >>>
                >>> Also, if someone know where to find information
                about IES files and their
                >>> format, that would also be really helpful.
                >>>
                >>> THANKS
                >>>
                >>> Germ�n
                >>>
                >>> _______________________________________________
                >>> Radiance-general mailing list
                >>> [email protected]
                <mailto:[email protected]>
                >>>
                http://www.radiance-online.org/mailman/listinfo/radiance-general
                >>>
                >>
                >> _______________________________________________
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Greg_Ward1 · November 11, 2015, 10:36pm

Yes, I forgot to mention about the other three params. I had it in mind when writing, but it slipped out. Glad you sorted it.

The approximation works at distance, but is slightly off as your test points get close to the source (within 7 times box size). There is an lboxcorr version, but requires the box be centered on origin.

More complex shapes require more complex form factors.

Cheers,
-Greg

···

Sent from my iPad

On Nov 11, 2015, at 11:07 AM, Germán Molina Larrain <[email protected]> wrote:

In the end, this is the illum modifier... I wonder about the src_theta parameter

void brightdata noGeo_illum_dist
4 boxcorr noGeo_illum.dat source.cal src_theta
0
4 1 0.1 0.1 0.1 # 1, dimx, dimy, dimz

2015-11-11 17:56 GMT-03:00 Germán Molina Larrain <[email protected]>:

Hi Greg,

Thanks very much for the information. I tried what you said, and I think that you might be slightly wrong.

- At First I did what you said... multiplied the original A1 value in brightdata (127.324) by Pi and by R2 (0.05*0.05) and the returned number was ridiculously close to 1, which is the -m option I input.

- I checked the surce.cal file, and the boxcorr requires A1, A2, A3 and A4... the first one being a multiplier and the others being the length, width and depth of the box. Using A1...A4 = 1 0.1 0.1 0.1, I got the following results

TOP VIEW
BOTTOM VIEW

One of them is using just ies2rad , the second is using ies2rad -i 0.05 and the third one is transforming this to a box as explained before.... THEY LOOK GOOD TO ME...?

I think the area and that kind of things has to be used for planar surfaces. right? I mean, for when we do crazier boxes...?

Regards,

Germán

2015-11-11 16:40 GMT-03:00 Greg Ward <[email protected]>:

Hi Germán,

Yes, it is a little more complicated, and you are right to worry about normals! Actually, it is the projected area that matters, which for the sphere is (mostly) constant. The main thing you need to do is to compute a first real brightdata argument (A1) equal to the existing one produced by ies2rad, multiplied by PI*R*R, where R is the radius of the original sphere. Multiplying the value thus by the projected area of the emitter gets you back to radiant intensity. Then, use the "boxcorr" function as the first string argument to the brightdata primitive in order that this radiant intensity is divided by the projected area in the appropriate direction during rendering.

It would be prudent to verify the results by rendering illuminance in a large sphere around the light source before and after, just to make sure neither of us messed up!

Cheers,
-Greg

From: Germán Molina Larrain <[email protected]>
Subject: Re: [Radiance-general] Luminaire modelling using Radiance
Date: November 11, 2015 9:29:48 AM HST

Hello again guys,

I have a question now.... I have been reading about all this, and I would like to input geometry surrounded by illum. However, ies2rad seem to only be able to generate a Sphere. How do I try this with different shapes? (i.e. a box) is it just a matter of deleting the Sphere and put a lot of Polygons with the same modifier? I am worried about normals and stuff like that.

I hope I made myself clear, haha

Regards,

Germán

2015-08-10 10:24 GMT-03:00 Germán Molina Larrain <[email protected]>:

well, thanks a lot guys! I have a lot to read, write, try and see now.... I will let you guys know how this goes and come back with a lot of new questions, haha.

Best,

Germán

2015-08-08 19:52 GMT-03:00 Randolph M. Fritz <[email protected]>:

"Further to Randolph’s post, the idea is to wrap the luminaire
geometry as tightly as possible using the shapes Randolph mentioned,
but this enveloping geometry will have *illum* applied to it, not
glow"

Duh. Rob is, of course, quite correct.
--
Randolph M. Fritz, Lighting Design and Simulation
+1 206 390 4477 || [email protected]

On Sat, Aug 8, 2015 at 1:59 PM, Rob Guglielmetti >>>>>> <[email protected]> wrote:
> Thomas has great info on lamp color and using replmarks. Further to
> Randolph’s post, the idea is to wrap the luminaire geometry as tightly as
> possible using the shapes Randolph mentioned, but this enveloping geometry
> will have *illum* applied to it, not glow. The glow is used to illuminate
> the luminaire geometry itself so that it appears realistic in a rendering.
> You apply glows to the lamp objects in the luminaire generally, or you could
> apply them to any shades or lenses in the luminaire.
>
> The luminous intensity of the illum is derived from the input lumens in the
> IES file and is modulated by a few cal files, which use the candela values
> from the IES file. The lamp color utility can give you reasonable values to
> use for the glows, based on lamp input lumens. Again, the glows illuminate
> the local luminaire geometry, and the illums actually illuminate the space.
> The ileum material is invisible when viewed directly, which is why you need
> the glows to make the luminaries appear correct in a rendering. The flux
> from the glow also does not make it past the illum geometry and so it does
> not contribute to the scene illumination or any calculations.
>
> There is some info on using illums and glows here:
>
> http://www.rumblestrip.org/using-the-illum-material-for-smoother-renderings-in-radiance/
>
> I did a bunch of crap with different illum geometry and cal files
> (lboxcorr.cal et al.) and got pretty good at picking the best ones for the
> jobs at hand (wall mounted sconces and stuff like that can be tricky to get
> looking “right”), but never got around to posting a summary on that stuff. A
> good place to start is just running a few different luminaire types though
> ies2rad and see what you get, and then play with the output files from
> there.
>
> Are we having fun yet?
>
> -Rob
>
> From: Randolph M. Fritz <[email protected]>
> Reply: Radiance general discussion <[email protected]>>
> Date: August 8, 2015 at 2:32:01 PM
> To: Radiance general discussion <[email protected]>>
> Subject: Re: [Radiance-general] Luminaire modelling using Radiance
>
> The basic technique is to wrap the visible geometry of the luminaire, if
> any, with a glow in a simple shape that actually radiates the light. The
> glow is transparent, so that the geometry can be seen, and direct
> illumination does not pass through the glow, so light can be used internal
> to the glow to give the luminaire a realistic look.
>
> The glow geometry and description may be generated by ies2rad. IIRC only
> four shapes are supported: sphere, rectangular, cuboid (box), and thin disc.
>
> Ies2rad does not support eulumdat and again, IIRC, has not been updated to
> support the latest IES photometry standard, LM-63-02.
>
> --
> Randolph M. Fritz, Lighting Design and Simulation
> +1 206 390 4477 || [email protected]
>
> On Sat, Aug 8, 2015 at 7:46 AM, Thomas Bleicher <[email protected]> wrote:
>> Hi German.
>>
>> The most important information you need you will find in the ies2rad man
>> page. In general you use it to create a library of luminaire *.rad and
>> *.dat
>> files which you can later reference into your scenes via xform. I found it
>> more convenient and flexible for my exporters to create files with
>> triangular markers and use "!replmarks ..." to place multiple luminaire
>> files. That way you can later replace all luminaires in an array with a
>> single change in the scene file.
>>
>> When you write a plugin you have to pay attention to the units of the ies
>> file and adjust the -d parameter accordingly. Unfortunately ies2rad
>> doesn't
>> read that information from the file.
>>
>> The geometry in IES files is limited to discs, ovals, rectangles and
>> extrusions of these shapes. Mostly you will find the 2 dimensional shapes
>> for recessed and spot lights while the 3 dimensional shapes are used for
>> pendants (boxes and cylinders). If you want to avoid these crude things in
>> your model and use detailed geometry instead (from a dxf file, for
>> example)
>> then you use the -i option to create an illum sphere. The sphere will be
>> used with the luminance data generated from the ies file. You have to
>> place
>> the detailed geometry of fixture into the sphere yourself. ies2rad doesn't
>> do that for you.
>>
>> I found that geometry provided by manufacturers is very detailed and can
>> lead to problems in large models. MGF geometry information is extremely
>> rare.
>>
>> You can use the -t option to set the lamp type. This defines the color
>> temperature. The -m option allows you to set a maintenance factor that all
>> artificial lighting calculations require. Not that some lamp type entries
>> in
>> the lamp.tab file already include a correction factor for the lamp so you
>> have to take this into account when calculating the final value of -m. I
>> found it safest to use "-t WHITE" (which does not have a correction) and
>> lump all the efficiency reductions and maintenance factors together into a
>> single -m value.
>>
>> European manufacturers provide are more likely to provide Eulumdat file
>> specs for their luminairs. Sometimes they convert these for you into IES
>> files. If you can only get LDT files you can use DIALUX or something
>> similar
>> to convert the LDT to IES files. It used to offer this option a few year
>> ago, at least. There may be other converters out there, but I don't
>> remember
>> the names.
>>
>> Hth, Thomas
>>
>> On Fri, Aug 7, 2015 at 2:09 PM, Germán Molina Larrain >>>>>> >> <[email protected]> >>>>>> >> wrote:
>>>
>>> Hello everyone,
>>>
>>> I think this might be a silly question, but I actually have not found too
>>> much information on how to model luminaires using Radiance... I am asking
>>> this because I want to add this feature to the plugin I am developing.
>>>
>>> What is the recommended method for modelling luminaires in Radiance? I
>>> intend to use IES files as input. Hopefully I would also have the
>>> geometry,
>>> but I have to consider cases when this is not available.
>>>
>>> I know there is an IES2RAD program, but I am not quite sure how general
>>> it
>>> is. Also, I have heard about the use of illums (a sphere, for example)
>>> that
>>> covers the entire luminaire....?
>>>
>>> I am kind of lost, so if someone could give me a hint, I would really
>>> appreciate it.
>>>
>>> Also, if someone know where to find information about IES files and their
>>> format, that would also be really helpful.
>>>
>>> THANKS
>>>
>>> Germán
>>>
>>> _______________________________________________
>>> Radiance-general mailing list
>>> [email protected]
>>> http://www.radiance-online.org/mailman/listinfo/radiance-general
>>>
>>
>>
>> _______________________________________________
>> Radiance-general mailing list
>> [email protected]
>> http://www.radiance-online.org/mailman/listinfo/radiance-general
>>
>
> _______________________________________________
> Radiance-general mailing list
> [email protected]
> http://www.radiance-online.org/mailman/listinfo/radiance-general
>
>
> _______________________________________________
> Radiance-general mailing list
> [email protected]
> http://www.radiance-online.org/mailman/listinfo/radiance-general
>

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German_Molina · November 11, 2015, 10:37pm

True, Jack... I was using different box and sphere sizes. Now it works
better.

I think that doing this for a box is fairly easy.

New images:

BOTTOM VIEW
<https://drive.google.com/file/d/0B2NfkTSl19hQY0FyVFh4cUV4Mms/view?usp=sharing>
TOP VIEW
<https://drive.google.com/file/d/0B2NfkTSl19hQdEVjcTMtVXNFS1k/view?usp=sharing>

···

2015-11-11 19:12 GMT-03:00 Jack de Valpine <[email protected]>:

Hi Germán,

I am following this somewhat peripherally, however I do note that from the
appearance of your test samples, in the bottom view, the right most sample
looks different. The higher end (the yellow portion) is smaller than in the
other two samples...

-Jack

On 11/11/2015 4:07 PM, Germán Molina Larrain wrote:

In the end, this is the illum modifier... *I wonder about the src_theta *
parameter

void brightdata noGeo_illum_dist
4 boxcorr noGeo_illum.dat source.cal src_theta
0
4 1 0.1 0.1 0.1 # 1, dimx, dimy, dimz

2015-11-11 17:56 GMT-03:00 Germán Molina Larrain <[email protected]>:

Hi Greg,

Thanks very much for the information. I tried what you said, and I think
that you might be slightly wrong.

- At First I did what you said... multiplied the original A1 value in
brightdata (127.324) by Pi and by R2 (0.05*0.05) and the returned number
was ridiculously close to 1, which is the -m option I input.

- I checked the surce.cal file, and the boxcorr requires A1, A2, A3 and
A4... the first one being a multiplier and the others being the length,
width and depth of the box. Using A1...A4 = 1 0.1 0.1 0.1, I got the
following results

TOP VIEW
<https://drive.google.com/file/d/0B2NfkTSl19hQVkdzN1JlWFllcE0/view>
BOTTOM VIEW
<https://drive.google.com/file/d/0B2NfkTSl19hQVXRvTXRWYV9hR2s/view?usp=sharing>

One of them is using just ies2rad , the second is using ies2rad -i 0.05
and the third one is transforming this to a box as explained before.... *THEY
LOOK GOOD TO ME...?*

I think the area and that kind of things has to be used for planar
surfaces. right? I mean, for when we do crazier boxes...?

Regards,

Germán

2015-11-11 16:40 GMT-03:00 Greg Ward < <[email protected]>
[email protected]>:

Hi Germán,

Yes, it is a little more complicated, and you are right to worry about
normals! Actually, it is the projected area that matters, which for the
sphere is (mostly) constant. The main thing you need to do is to compute a
first real brightdata argument (A1) equal to the existing one produced by
ies2rad, multiplied by PI*R*R, where R is the radius of the original
sphere. Multiplying the value thus by the projected area of the emitter
gets you back to radiant intensity. Then, use the "boxcorr" function as
the first string argument to the brightdata primitive in order that this
radiant intensity is divided by the projected area in the appropriate
direction during rendering.

It would be prudent to verify the results by rendering illuminance in a
large sphere around the light source before and after, just to make sure
neither of us messed up!

Cheers,
-Greg

*From: *Germán Molina Larrain <[email protected]>

*Subject: *Re: [Radiance-general] Luminaire modelling using Radiance

*Date: *November 11, 2015 9:29:48 AM HST

Hello again guys,

I have a question now.... I have been reading about all this, and I
would like to input geometry surrounded by illum. However, ies2rad seem to
only be able to generate a Sphere. How do I try this with different shapes?
(i.e. a box) is it just a matter of deleting the Sphere and put a lot of
Polygons with the same modifier? I am worried about normals and stuff like
that.

I hope I made myself clear, haha

Regards,

Germán

2015-08-10 10:24 GMT-03:00 Germán Molina Larrain <
<[email protected]>[email protected]>:

well, thanks a lot guys! I have a lot to read, write, try and see
now.... I will let you guys know how this goes and come back with a lot of
new questions, haha.

Best,

Germán

2015-08-08 19:52 GMT-03:00 Randolph M. Fritz < <[email protected]>
[email protected]>:

"Further to Randolph’s post, the idea is to wrap the luminaire
geometry as tightly as possible using the shapes Randolph mentioned,
but this enveloping geometry will have *illum* applied to it, not
glow"

Duh. Rob is, of course, quite correct.
--
Randolph M. Fritz, Lighting Design and Simulation
+1 206 390 4477 <%2B1%20206%20390%204477> || <[email protected]>
[email protected]

On Sat, Aug 8, 2015 at 1:59 PM, Rob Guglielmetti >>>>> < <[email protected]>[email protected]> wrote:
> Thomas has great info on lamp color and using replmarks. Further to
> Randolph’s post, the idea is to wrap the luminaire geometry as
tightly as
> possible using the shapes Randolph mentioned, but this enveloping
geometry
> will have *illum* applied to it, not glow. The glow is used to
illuminate
> the luminaire geometry itself so that it appears realistic in a
rendering.
> You apply glows to the lamp objects in the luminaire generally, or
you could
> apply them to any shades or lenses in the luminaire.
>
> The luminous intensity of the illum is derived from the input lumens
in the
> IES file and is modulated by a few cal files, which use the candela
values
> from the IES file. The lamp color utility can give you reasonable
values to
> use for the glows, based on lamp input lumens. Again, the glows
illuminate
> the local luminaire geometry, and the illums actually illuminate the
space.
> The ileum material is invisible when viewed directly, which is why
you need
> the glows to make the luminaries appear correct in a rendering. The
flux
> from the glow also does not make it past the illum geometry and so
it does
> not contribute to the scene illumination or any calculations.
>
> There is some info on using illums and glows here:
>
>
<http://www.rumblestrip.org/using-the-illum-material-for-smoother-renderings-in-radiance/>
http://www.rumblestrip.org/using-the-illum-material-for-smoother-renderings-in-radiance/
>
> I did a bunch of crap with different illum geometry and cal files
> (lboxcorr.cal et al.) and got pretty good at picking the best ones
for the
> jobs at hand (wall mounted sconces and stuff like that can be tricky
to get
> looking “right”), but never got around to posting a summary on that
stuff. A
> good place to start is just running a few different luminaire types
though
> ies2rad and see what you get, and then play with the output files
from
> there.
>
> Are we having fun yet?
>
> -Rob
>
> From: Randolph M. Fritz < <[email protected]>[email protected]>
> Reply: Radiance general discussion <
<[email protected]>
[email protected]>>
> Date: August 8, 2015 at 2:32:01 PM
> To: Radiance general discussion <
<[email protected]>
[email protected]>>
> Subject: Re: [Radiance-general] Luminaire modelling using Radiance
>
> The basic technique is to wrap the visible geometry of the
luminaire, if
> any, with a glow in a simple shape that actually radiates the light.
The
> glow is transparent, so that the geometry can be seen, and direct
> illumination does not pass through the glow, so light can be used
internal
> to the glow to give the luminaire a realistic look.
>
> The glow geometry and description may be generated by ies2rad. IIRC
only
> four shapes are supported: sphere, rectangular, cuboid (box), and
thin disc.
>
> Ies2rad does not support eulumdat and again, IIRC, has not been
updated to
> support the latest IES photometry standard, LM-63-02.
>
> --
> Randolph M. Fritz, Lighting Design and Simulation
> +1 206 390 4477 <%2B1%20206%20390%204477> || <[email protected]>
[email protected]
>
> On Sat, Aug 8, 2015 at 7:46 AM, Thomas Bleicher < >>>>> <[email protected]>[email protected]> wrote:
>> Hi German.
>>
>> The most important information you need you will find in the
ies2rad man
>> page. In general you use it to create a library of luminaire *.rad
and
>> *.dat
>> files which you can later reference into your scenes via xform. I
found it
>> more convenient and flexible for my exporters to create files with
>> triangular markers and use "!replmarks ..." to place multiple
luminaire
>> files. That way you can later replace all luminaires in an array
with a
>> single change in the scene file.
>>
>> When you write a plugin you have to pay attention to the units of
the ies
>> file and adjust the -d parameter accordingly. Unfortunately ies2rad
>> doesn't
>> read that information from the file.
>>
>> The geometry in IES files is limited to discs, ovals, rectangles and
>> extrusions of these shapes. Mostly you will find the 2 dimensional
shapes
>> for recessed and spot lights while the 3 dimensional shapes are
used for
>> pendants (boxes and cylinders). If you want to avoid these crude
things in
>> your model and use detailed geometry instead (from a dxf file, for
>> example)
>> then you use the -i option to create an illum sphere. The sphere
will be
>> used with the luminance data generated from the ies file. You have
to
>> place
>> the detailed geometry of fixture into the sphere yourself. ies2rad
doesn't
>> do that for you.
>>
>> I found that geometry provided by manufacturers is very detailed
and can
>> lead to problems in large models. MGF geometry information is
extremely
>> rare.
>>
>> You can use the -t option to set the lamp type. This defines the
color
>> temperature. The -m option allows you to set a maintenance factor
that all
>> artificial lighting calculations require. Not that some lamp type
entries
>> in
>> the lamp.tab file already include a correction factor for the lamp
so you
>> have to take this into account when calculating the final value of
-m. I
>> found it safest to use "-t WHITE" (which does not have a
correction) and
>> lump all the efficiency reductions and maintenance factors together
into a
>> single -m value.
>>
>> European manufacturers provide are more likely to provide Eulumdat
file
>> specs for their luminairs. Sometimes they convert these for you
into IES
>> files. If you can only get LDT files you can use DIALUX or something
>> similar
>> to convert the LDT to IES files. It used to offer this option a few
year
>> ago, at least. There may be other converters out there, but I don't
>> remember
>> the names.
>>
>> Hth, Thomas
>>
>> On Fri, Aug 7, 2015 at 2:09 PM, Germán Molina Larrain >>>>> >> < <[email protected]>[email protected]> >>>>> >> wrote:
>>>
>>> Hello everyone,
>>>
>>> I think this might be a silly question, but I actually have not
found too
>>> much information on how to model luminaires using Radiance... I am
asking
>>> this because I want to add this feature to the plugin I am
developing.
>>>
>>> What is the recommended method for modelling luminaires in
Radiance? I
>>> intend to use IES files as input. Hopefully I would also have the
>>> geometry,
>>> but I have to consider cases when this is not available.
>>>
>>> I know there is an IES2RAD program, but I am not quite sure how
general
>>> it
>>> is. Also, I have heard about the use of illums (a sphere, for
example)
>>> that
>>> covers the entire luminaire....?
>>>
>>> I am kind of lost, so if someone could give me a hint, I would
really
>>> appreciate it.
>>>
>>> Also, if someone know where to find information about IES files
and their
>>> format, that would also be really helpful.
>>>
>>> THANKS
>>>
>>> Germán
>>>
>>> _______________________________________________
>>> Radiance-general mailing list
>>> <[email protected]>
[email protected]
>>> <http://www.radiance-online.org/mailman/listinfo/radiance-general>
http://www.radiance-online.org/mailman/listinfo/radiance-general
>>>
>>
>>
>> _______________________________________________
>> Radiance-general mailing list
>> <[email protected]>
[email protected]
>> <http://www.radiance-online.org/mailman/listinfo/radiance-general>
http://www.radiance-online.org/mailman/listinfo/radiance-general
>>
>
> _______________________________________________
> Radiance-general mailing list
> <[email protected]>
[email protected]
> <http://www.radiance-online.org/mailman/listinfo/radiance-general>
http://www.radiance-online.org/mailman/listinfo/radiance-general
>
>
> _______________________________________________
> Radiance-general mailing list
> <[email protected]>
[email protected]
> <http://www.radiance-online.org/mailman/listinfo/radiance-general>
http://www.radiance-online.org/mailman/listinfo/radiance-general
>

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Thomas_Bleicher2 · November 12, 2015, 1:46am

German

Have you tried to change the geometry identifier in the IES file to
indicate a box geometry. I am a bit rusty on the specs but I don't think
anything else depends on this information so the change should be simple to
do. The transformation in a Radiance box is then done by ies2rad.

Regards,
Thomas

···

On Fri, Aug 7, 2015 at 1:09 PM, Germán Molina Larrain <[email protected]> wrote:

Hello everyone,

I think this might be a silly question, but I actually have not found too
much information on how to model luminaires using Radiance... I am asking
this because I want to add this feature to the plugin I am developing.

What is the recommended method for modelling luminaires in Radiance? I
intend to use IES files as input. Hopefully I would also have the geometry,
but I have to consider cases when this is not available.

I know there is an IES2RAD program, but I am not quite sure how general it
is. Also, I have heard about the use of illums (a sphere, for example) that
covers the entire luminaire....?

I am kind of lost, so if someone could give me a hint, I would really
appreciate it.

Also, if someone know where to find information about IES files and their
format, that would also be really helpful.

THANKS

Germán

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Christopher_Rush · November 13, 2015, 3:33pm

If you want to try Thomas’ recommendation, look in the IES file for a pair of lines just below the header that look like this. I’m borrowing the example out of Ian Ashdown’s “Thinking Photometrically Part II” which you can easily find online.
1 50000 1 5 3 1 1 .5 .6 0
1.0 1.0 495

In that example the 50000 represents number of lumens (now sometimes noted as -1 for LED luminaires tested differently), 495 represents number of Watts, and the values 0.5, 0.6, 0 represent the X, Y, and Z dimensions of a rectangular luminaire. In some cases, certain dimensional values could be given as negative, which signifies various types of rounded shapes for interpretation by software.

You can freely change the XYZ values in the IES file without affecting the data. Only when you import the IES file through IES2RAD (or into Dialux, AGI, etc.) does software interpret the dimensions and apply the brightness functions across the appropriate surface areas given by the dimensions.

-Chris

···

From: Thomas Bleicher [mailto:[email protected]]
Sent: Wednesday, November 11, 2015 8:47 PM
To: Radiance general discussion
Subject: Re: [Radiance-general] Luminaire modelling using Radiance

German

Have you tried to change the geometry identifier in the IES file to indicate a box geometry. I am a bit rusty on the specs but I don't think anything else depends on this information so the change should be simple to do. The transformation in a Radiance box is then done by ies2rad.

Regards,
Thomas

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Guglielmetti_Robert · November 13, 2015, 3:59pm

That's right, you can use the geometry fields to describe the shape of the "luminous opening" as it says in the IES doc (LM-63). These change the geometry, but do not at all affect the luminous flux. By changing the geometry fields you can end up with a decent approximation of the illum bounding box or sphere you need. With the lampcolor utility, you can get reasonable values for the glow materials you need to apply to the proxy lamp or lens geometry you have contained by the illum(s). Finally with proper use of the cal files (lboxcorr et al.) you can essentially map the candelas to the illums. So there's a bit of hand editing required after the initial IES2RAD step if you really want the appearance of the luminaries to be proper.

···

On 11/13/15, 8:33 AM, "Christopher Rush" <[email protected]<mailto:[email protected]>> wrote:

If you want to try Thomas' recommendation, look in the IES file for a pair of lines just below the header that look like this. I'm borrowing the example out of Ian Ashdown's "Thinking Photometrically Part II" which you can easily find online.
1 50000 1 5 3 1 1 .5 .6 0
1.0 1.0 495

In that example the 50000 represents number of lumens (now sometimes noted as -1 for LED luminaires tested differently), 495 represents number of Watts, and the values 0.5, 0.6, 0 represent the X, Y, and Z dimensions of a rectangular luminaire. In some cases, certain dimensional values could be given as negative, which signifies various types of rounded shapes for interpretation by software.

You can freely change the XYZ values in the IES file without affecting the data. Only when you import the IES file through IES2RAD (or into Dialux, AGI, etc.) does software interpret the dimensions and apply the brightness functions across the appropriate surface areas given by the dimensions.

-Chris