On 03/23/2013 07:18 PM, clipka wrote:
> Am 21.03.2013 15:48, schrieb James Holsenback:
>
>>> what's up with blotches? change #5819/5820 (octree) or maybe something
>>> still with area lights?
>
> Octree problems look way different.
>
>> OK ... turning area_illumination off got rid of the blotches!
>
> Crap - I guess I have an idea what's happening there. I happen to know
> that in a portion of code that is called both for each individual point
> light as well as each "lightlet" of standard area lights, and which
> dispatches to the computations of the diffuse, specular, phong and ior
> components, there is some test to make sure that highlights are not
> computed for radiosity secondary rays. There exist two other, very
> similar pieces of code to handle photons and the "lightlets" of
> area_illumination lights respectively, which both /should/ have the same
> test as well, but I bet the area_illumination variant of the code
> doesn't. The result would be that a few radiosity samples would pick up
> that highlight as an extremely bright light (boosting the sample's total
> brightness a lot), while most samples would just miss it entirely.
>
> (Without the test, if you'd crank the radiosity count up to insane
> values you could actually use this mechanism to compute reflective
> caustics. It would be extremely ineffective though, so we leave that up
> to photons in combination with proper reflection.)
>
> It'll take me a few days to look into this; in the meantime, could you
> please file a bug report, and maybe already have a first glance at the
> code to check whether I'm right?
>

I filed a bug report the other day when I posted ... You know I've seen 
this for a while now, but thought I was struggling with getting the 
proper radiosity settings. The sslt problem you recently fixed gave me 
the hint to try turning off area_illumination.

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