[Radiance-general] Sunlight through glass

[Greg Ward]

Hi Kirk,

I think the challenge to rendering the interior of a building through  
a glass facade is exactly the same trouble you would have  
photographing it -- the reflections will tend to overwhelm the  
interior unless there is direct sun penetrating the space, something  
architects try to avoid.  Typically, an interior is less than 10% as  
bright as the exterior during daylight conditions, and this is  
(roughly) the amount of light reflected by standard glass.   
Therefore, the reflections are intermixing with the light from the  
interior, and it's difficult to see any details that aren't confused.

Things are made better if you can get just blue sky or something  
without detail in the reflection, or use a polarizing filter and  
shoot near the Brewster angle, where all the reflected light is of a  
particular polarization.  This would be a nice trick that Radiance  
(unfortunately) cannot do properly, as it lacks polarization in its  
simulation.  (Well, we had to cut back somewhere...)

-Greg