[Radiance-general] trans or glass material, rectangular luminous opening problem

[Gregory J. Ward]

Hi Christian,


> 1. question:
>
> I have circular plexiglass disc or more a  flat cylinder  and  on  
> top of one side there is a blue LEE Color filter attached. I have  
> the spectrum of the filter and calculated the RGB color values.  
> Shall i make a normal glass cylinder and on top a disc of glass  
> with the RGB values multiplied with the transmittance of the  
> filter? Or would you suggest the trans material ?

The glass material is probably a better approximation in this case,  
as it will account for the change in reflection and transmission with  
angle.

> 2. I have .ies data of a rectangular flood light and convert it  
> into a radiance file. Although the resulting Polygon is glowing,    
> the light output  seems to come from the middle of the polygon and  
> not from the whole area. Is this correct?

That is correct.  If you set the -dj option to something between 0.5  
and 0.8, you will sample over a larger subregion.  (A setting of -dj  
1 is allowed, but only works if all the sources in your scene are  
rectangular.)

-Greg