I converted the cornell.rib file that comes with BMRT to test radiosity
in MegaPOV.  The results are interesting but somewhat discouraging.  I
tried to use the same settings.

The first image is rendered in MegaPOV using radiosity count of 100 and
recursion 2.  There's an area_light with an 8x8 array of samples and a
patch of the same size with an ambient of 1.  It took 7 minutes to
render.

The second one is the scene rendered in BMRT using radiosity and 2
bounces (I think) and 8 nsamples in the area light, radiosity steps was
100.  Render time was 5 minutes.

Probably the only thing I wasn't able to translate was the falloff to
the area light in BMRT, as the shader source puts it "cosine falloff
from the normal of the light source surface", whatever that means.  I
have to admit that the BMRT version looks more realistic.

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