[Radiance-general] Approximating the gross daylight flux through venetian blinds.

[Greg Ward]

I gave it a little more thought, and I'm note sure how useful it would 
be to have a BRTDfunc that approximates the aggregate behavior of 
venetian blinds.  The only context where this might prove useful is in 
performing daylight analyses where you don't care about external 
reflections and the users doesn't care to visualize the space.  Because 
a BRTDfunc doesn't include the directional-diffuse portion in its 
indirect component, it wouldn't get an accurate contribution from light 
reflected off external surfaces.  The best it could do is get a 
reasonable value for the indirect solar due to light hitting the blinds 
directly.  Mathematically, even this would be difficult -- I'm guessing 
it would take me a day or two  to work up a reasonable approximation.  
As far as the appearance goes, one would see a semi-translucent 
material if one was to visualize your model with this material, which 
wouldn't end up looking like blinds at all.

In summary, I don't think this would be much of an improvement over a 
mkillum solution.  Does anyone else have some thoughts on this?

-Greg