Warp wrote:
>   Photon mapping global illumination has already been tried, and it didn't
> work too well. The results were much worse than the stochastic technique
> currently used.

Hmm, it's the method used by high end renderers like Mental Ray.

>   The whole idea of the stochastic algorithm used in POV-Ray is that you
> *can* save the results and then render from a different angle and have
> POV-Ray only calculate the necessary additional samples for that angle.
> If the save/load feature is not doing that, then maybe file a bug report?

Hmm, perhaps to calculate the additional samples for the other angle 
means letting always_sample on in the second phase?  Never did that and 
so I discovered areas hidden from the original angle sucked from 
another.  It seems messing with camera's sky also messes with the 
radiosity projection onto the raytraced scene.

>   You make it sound like it's a bad idea to calculate GI samples only for
> the visible scene.

No, I was just wondering why I couldn't reuse a saved file that took 
ages and render it from another angle with always_sample off.  Seemed to 
beat the whole purpose...

>   A renderer called Radiance successfully implemented the exact algorithm
> which is also used in POV-Ray

Yes, I know that. "POV-Ray's radiosity is based on an idea by Greg Ward".

I always wanted to use Radiance, but it's RIB-like input language is 
horrid compared to pov's and there are too many specialized command-line 
tools for my liking, with no front-end of any kind.

>   I'd say that rather than drop the algorithm, what's needed is a complete
> rewrite. Read the original paper by Greg Ward, and study how Radiance did
> it correctly and what POV-Ray is doing incorrectly, and fix the problems.

Why stick with old ideas when new and exciting ideas building on 
previous failures appear to be successful?

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