[Radiance-general] modeling external glass lamella incl discription of trans data

[Greg Ward]

Hi Anne,

The first trans definition should be correct.  The best thing to do  
at this point is to e-mail me your model so I can run the simulations  
and debug them on my end.  Don't send it to the list.

Thanks!
-Greg

> From: Anne Iversen <iversen.anne at gmail.com>
> Date: March 26, 2009 2:33:55 AM PDT
>
> Hi Rob and Greg,
> Thanks for your answers!
> I have carried out simulations with two different definitions of  
> trans, but I get the same result for each type of trans. For both  
> approaches, when checking the material under a glow sky, I get the  
> reflectance 0.31 when looking down on the glass and I get the  
> transmittance 0.65 when looking in the direction upwards.
>
> I have listed my discription of trans below - looking forward to  
> hearing your comments.
>
> Br
> Anne
>
> The trans data is defined as:
> # a1, a2 og a3 = 1, due to the color of the glass is included in  
> the transmittance end reflectance given by the manufacturer
> # a4 = 0,31
> # a5 = 0
> # a6 = trans, determined from t_s=a6*a7(1-a4), where t_s is 0.65  
> and a7=1
> # a7 = 1
>
> void trans lamel_trans
> 0
> 0
> 7  1 1 1 0.31 0 0.942028986 1
>
> I have also tried to define my trans material according to the  
> description in http://www.schorsch.com/rayfront/manual/transdef.html.
> #Spec=Light reflectance = 0.31
> #The color of the glass is determined from:
> #Absorptance=(1-spec)(1-color) -> 0.04 = (1-0.31)(1-color), from  
> where the color is found to be 0.94
> #Transmittance = (1-spec) *color* trans, transmittance is 0.65 and  
> trans can then be found to be 1
> #Rough is set to 0, as the material is glass
> #Tr-spec is set to 1, as the glass is a clear glass material
>
>
> void trans lamel_transrayfront
> 0
> 0
> 7  0.94 0.94 0.94 0.31 0 1 1