nemesis schrieb:

> I'm mostly amused by the noise in that image.  I thought radiosity was mostly
> patchy...

I'm not sure what you're talking about; as for the clothes, they use a 
very small-patterned texture; and the walls uses small-scaled bumps.

As for the "light leaks" to the left of the wall, they are quite pointy 
due to the pathologically high sample density.

> Radiosity is not right for this kind of scene.

That's a perfectly correct observation, and I'd try bidirectional 
tracing anytime if it was implemented in POV-Ray :-P

 > I'm fed up trying to make it
> work right under the assumption that any object may emit light.  See that hand
> emitting light?  See the corners of the room emitting light?  Fact is that when
> you force it to treat a bright object outside as emitting light, other geometry
> too close to each other also begin to misteriously emit light themselves.

Yes, that's the symptoms we see, but...

 > It
> doesn't simulate light, only radiation from surfaces and we not always want that
> radiation.

... I don't know whether you understand how POV-Ray's radiosity works. 
It does /not/ assume that /all/ surfaces emit light - it doesn't even 
focus on /emitted/ light; what it does is choose sample points for which 
it computes the amount of incoming light by means of classic raytracing 
during a pretrace pass, then during final trace interpolate between 
nearby sample points.

The problem here is that depending on geometry it may fail to recognize 
that a certain sample point is absolutely unfit to serve as a reference 
to interpolate from.

> MCPov is not a good option for this because AFAIK, it only implements simple
> path tracing.  Scenes with very small openings through which the light may pass
> is a very hard challenge for plain random path tracing:  most light paths will
> simply not go through.  It's unbiased, so it'll eventually converge into the
> right image, but may take ages.

MCPov does provide means to "hint" a scene, so that the tracing 
algorithm will favor rays pointing at particular objects or regions in 
3D space (weighting them to compensate of course), so that those regions 
are scanned at a higher "resolution" than others.

> This Blender scene rendered with Lux took 4 hours for a total of 970
> samples/sec on my Q6600 (only 3 cores, one for web surfing :):
> 
> http://img534.imageshack.us/img534/24/mlt4h970sps.jpg

Note that the geometry of your scene lacks one particularly difficult 
feature of mine: The door is closed so much that light cannot travel 
directly from one room to the other, but must do at least one bounce 
between door and frame. With the setup of your scene, I guess mine would 
yield pleasing results as well, even with much simpler radiosity 
settings, as the illumination of the adjacent room could be way lower, 
while "this" room would be much brighter, so that the visual impact of 
"light leaks" would be reduced a good deal.

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