[Radiance-general] clipping planes exposing object interiors?

[Carsten Bauer]

Hi Paul,

sorry, with that separate cache I was referring to a still somewhat 
experimental radzilla feature ('scene') which is not present in classic 
Radiance

sticking to classic Radiance, or in fact general, the key point to keep 
in mind is perhaps that the ambient cache is independent of the 
geometry. This means except for the surface normal present at creation, 
there is no other geometry info the ambient cache can use for deciding 
if it's 'allowed' to use a cached value or not. So it is vital to
use a correct -ar resolution value, otherwise the cache cannot adapt 
itself adequately (means closer spaced sample points) in regions with 
high variation of illumination.
(Maybe expressed a bit simplified, Greg pelase correct me if I'm wrong :-).

Taken this little amount of info known to the algorithm, the ambient 
cache in fact does quite a good job in sorting out things, and you see 
the effect of a higer -ar value in your rendering, the  amount of spill 
light in the left wall is much lesser now.

Generally, I would not bother too much about this, as in fact the hollow
wall is an unphysical situation anyway. In reality, there's conrete 
inside. And a real, i.e. thick wall also means a greater distance 
between points outside and inside the room, and together with an 
adequate resolution value this makes it much easier then for the ambient 
algorithim to get things right, i.e. not use values from the outside for 
the inside.

-cb