clipka <ano### [at] anonymousorg> wrote:
> Render time: Days. Something around 48 hours I guess.

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

Radiosity is not right for this kind of scene.  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.  It
doesn't simulate light, only radiation from surfaces and we not always want that
radiation.

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.

Metropolis Light Transport combined with the more robust Bidirectional Path
Tracing -- where lights are traced both from the camera and from light sources
-- is far more effective at that, converging much, much faster:

http://graphics.stanford.edu/papers/metro/

It was formulated with that precise kind of issue in mind.

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

You'd need much more samples with plain path tracing.  The only light source is
a small Blender plane giving light outside.  Geometry of course is not nearly as
complex except for the 2 monkeys -- I just quickly hacked this up -- but you get
the idea... it's still a full room with proper thick walls, floor and ceiling.

OTOH, althought it shows no double-illuminate nor SSS, the 2 monkeys sport a
copper material and a jade glass one.  Seen on the scene are glossy reflections,
some very slight indirectly-lit reflective and refractive caustics and crisp
smooth shadows under the table legs from indirect light.  None of which come
with radiosity, which means fill lights should be set up and tested.

It's not even using portals because for some reason the binary I have here was
complaining it was not possible to "statically load" the portal material.  guess
I should update... anyway, MLT is able to just find the right paths.

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