Warp wrote:
>   POV-Ray's stochastic global illumination algorithm is still "backwards
> raytracing" because it traces from surfaces to other surfaces and from
> there to the light sources (ie. it still traces back how light traverses).
> POV-Ray's photon mapping algorithm is a genuine "forward raytracing"
> feature.

Duh, I know that :)

Actually, this brings up one point I've run into in the past: since 
POV-Ray computes radiosity samples by tracing rays from the camera, and 
then lighting them, I've run into some issues in scenes lit entirely by 
radiosity that don't light up the way they should (for instance, if a 
large object with high ambience is partially (or entirely) out of view).

I suppose that building a radiosity cache, by doing "forward tracing" 
(from the light source) pretrace, would be beneficial in such scenes. 
However, I can't imagine its very high on the priority list.

...Chambers

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