BRTDfunc (Lars O. Grobe)

Hi Lars,

Thanks for your responding my question. I have used the glass function but I
can only chance the transmission of this pane and not the reflection. In my
project is the reflection of this pane very important and I was thinking the
BRTDfunc will help me whit this. So for that I have found the glazing.cal
file in the library to calculate my glas but is ther also an explanation of
these calculations

cheers, Sierd.

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···

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Onderwerp: Radiance-general Digest, Vol 119, Issue 9

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   1. Re: BRTDfunc (Lars O. Grobe)

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

Message: 1
Date: Fri, 10 Jan 2014 00:44:02 +0100
From: "Lars O. Grobe" <[email protected]>
To: Radiance general discussion <[email protected]>
Subject: Re: [Radiance-general] BRTDfunc
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"

Hi Sierd,

if all you need to model is a clear glass pane, do not use BRTDfunc but
glass. That is an optimized modifier modeling transmission and reflection
for thin glass panes surrounded by air (which is a function of the direction
a ray is passing through).

BRTDfunc is meant to describe transmission and reflection using the
mathematical description language of Radiance (see the cal-files coming in
the library). It does not make sense to use it without any mathematical
model.

Cheers, Lars.

09.01.2014 tarihinde 18:10 saatinde, "Sierd Tilma" <[email protected]>
?unlar? yazd?:

Hello all,

I found the BRTDfunc in the reference manual off Radiance, but I don't
understand fully how this function is working

I have a glass whit a transmittance of 0,8 and an reflectance of 0,08

I was thinking to do link this

void BRTDfunc testing_glass
10
                0.08 0.08 0.08

[I was thinking this is the reflection]

                0.87154 0.87154 0.87154

[I was thinking this is the transmision]

                0 0

0

                .
0
9
                0 0 0
                0 0 0
                0 0 0

but this is nog working it seems like my glas is giving light

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What is your method for determining the transmission and reflectance of the glass? Are you familiar with the Optics software and the international glazing database? There is also an interactive script "glaze" that allows you to define multi-pane glazing and some basic coatings.

···

-----Original Message-----
From: Sierd Tilma [mailto:[email protected]]
Sent: Monday, January 13, 2014 10:51 AM
To: [email protected]
Subject: Re: [Radiance-general] BRTDfunc (Lars O. Grobe)

Hi Lars,

Thanks for your responding my question. I have used the glass function but I
can only chance the transmission of this pane and not the reflection. In my
project is the reflection of this pane very important and I was thinking the
BRTDfunc will help me whit this. So for that I have found the glazing.cal
file in the library to calculate my glas but is ther also an explanation of
these calculations

cheers, Sierd.

____________________________________________________________
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systems are scanned for acceptability of content and viruses

Hi Sierd,

as Christopher wrote in his mail, you should consider Optics as a starting point if you have a e.g. coated glazing. Whatever you do, reflection and transmission should be a function of the incident direction for clear glazings. One other approach may be the trans material, which allows to define reflection and transmission at normal incidence. The angular dependance will follow a Fresnel-term if you stay with only clear transmission and reflection, roughness=0. This may be what you want?

Peter did a very nice comparision on the various models available in Radiance:

Cheers, Lars.

···

Hi Lars,

Thanks for your responding my question. I have used the glass function but I
can only chance the transmission of this pane and not the reflection. In my
project is the reflection of this pane very important and I was thinking the
BRTDfunc will help me whit this. So for that I have found the glazing.cal
file in the library to calculate my glas but is ther also an explanation of
these calculations

cheers, Sierd.