Glad I could help :)

I've been meaning to compile povray for a while (so I can make a few 
changes), and this might finally give me the excuse I need.

-- 
Tek
http://evilsuperbrain.com


"clipka" <ano### [at] anonymousorg> wrote in message 
news:4bc259cd$1@news.povray.org...
> Am 11.04.2010 16:34, schrieb Tek:
>
>> I get it in both Megapov 1.21&  Povray 3.6. I might try moving over to 
>> 3.7
>> but my scene's probably using a couple of megapov features.
>
> Um, sorry... I'm so focused on POV-Ray 3.7 that it didn't even cross my 
> mind that you may still be using 3.6. >_<
>
>>> What is strange, is the fact that the artefacts are of the complementary
>>> colour.
>>
>> It's as if it's using negative lighting values.
>
> It is indeed! Thanks for pointing me in the right direction, that did ring 
> a bell:
>
> At each radiosity sample location, POV-Ray 3.6 does not only compute the 
> total incoming diffuse illumination, but also tries to guesstimate the 
> illumination /gradient/ at that point.
>
> I had always been suspicious of that mechanism's implementation, though I 
> never managed to demonstrate its bogosity with a sample scene. On the 
> other hand I couldn't make out any noticeable benefits either, so I 
> decided to disable it in POV-Ray 3.7, if only to save memory and 
> processing time.
>
> To verify this theory, I just threw together a patched 3.7.0.beta.36 with 
> the "gradient code" re-enabled, and it did indeed show the very same 
> complementary-color halos (current official 3.7 betas don't, as already 
> mentioned in this thread).
>
> Patching POV-Ray 3.6 (or MegaPOV, for that matter) to fix this issue 
> should be pretty easy: In radiosity.cpp, just delete (or comment out) the 
> line reading:
>
>     #define RAD_GRADIENT 1
>
> That should be all that's needed.

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