Yes.  It's a bug.  Found and fixed (for the next release of UVPov).  It was
a bit of legacy code (from the original radiosity) that was messing up my
changes.  It was caused by some code in the supersample() function related
to antialiasing.

I had seen this before but didn't make the connection between antialiasing
and the dark spots.

-Nathan

Margus Ramst <mar### [at] peakeduee> wrote...
> Render the example scene below, with the new UVPov. You should see darker
> patches behind the two objects. Here are a few observations:
> 1) It only appears when antialiasing is on, and only during the final
pass.
> Probably some calculation is omitted with sub-pixel rays.
> 2) Very high quality (many rays, low error_bound) will eliminate (or
obscure?)
> the dark patches, but other freaky things occur (see for yourself). Maybe
> related, maybe not.
>
> I'm wondering if this has something to do with the non-constant
> distance_maximum, since the problem seems to occur on a flat background
around
> outstanding objects... I may be wrong, though.
>
> Margus
>

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