[Radiance-general] Trans material

[Lars O. Grobe]

Hi Per.

a side note on your material definition. Ts of zero is difficult to achieve for transmission with real glass, as that would be a perfect lambertian diffuser. Did you do any test or measurement confirming this? You can see some examples of real world translucent glasses (sanded, or with scattering films applied) on Peter's BME site: http://www.pab.eu/gonio-photometer/demodata/bme/

A quick test I tend to do is pointing a small laser pointer at the glass (be careful, there may be strong reflection from the glass which you probably do not want to reach your eye) held just one cm onver a piece of paper. If you see a smooth gradient, it is a perfect diffuser. If you still see the dot of the pointer, with a smooth gradient around, you have a mixture of diffuse and specular transmission. That ratio could get measured using an intergrating sphere, or you could have the BSDF measured.

Cheers, Lars.

> 
> Cr	Cg	Cb	Rd	Rs	Sr	Td	Ts
> 0,1	0,1	0,1	0,1	0,08	0,02	0,5	0
> A1	A2	A3	A4	A5	A6	A7
> 0,65	0,65	0,65	0,08	0,02	0,83	0,00

CU Lars.
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