[Radiance-general] glass diffuser?

[Lars O. Grobe]

Hi Victor!

> frosted glass can scatter sunlight to avoid glare buy it would  have 
> lower transmittance.

Yes, as the scattering results in some of the light being reflected 
back, the transmittance has to be lower.

> You just mentioned a structure with clear glass, acrylic, polycarbonat. 
> I am wondering what kind of structure it is and is any product in the 
> market?

There are lots of products, if you look at what companies are offering 
for "advanced daylighting", "daylight redirecting", you will find many 
options. It all depends on your application. Most systems either use 
refraction or total reflection to have a dielectric surface redirect 
light. Sometimes this works like with lenses, sometimes it is simply 
reflecting light from selected directions into another direction.

> i am using Desktop Radiance. How can i difine this kind of property in 
> Desktop radiance?

In general - not at all. Most of these systems can be modeled using the 
photon map, which is an addition to Radiance but not part of Desktop 
Radiance. There is also rtcontrib which may be used, but this is a 
rather new tool, while Desktop Radiance, as far as I know, is based on 
very old code. It is possible to model redirecting materials as long as 
they do not concentrate light (so most planar surfaces) using prism.

> By the way i am wondering, Radiance for UNIX and Desktop Radiance which 
> one is more popular and more people use?

I was not aware of anyone using Desktop Radiance any more. As far as I 
know, all updates during the recent years were in Radiance only, I do 
not know whether anyone is working on Desktop Radiance. Folks on windows 
systems in general use one of the windows distributions of Radiance, 
people who need integration into a GUI have options like brad or the 
Sketchup-extension, there are tools such as Rayfront. I do not know 
anyone using Desktop Radiance these days.

Cheers, Lars.