Importance sampling and sharp shadows in IBL

[Dawa <dawa(at)topixfx.com>]

We are trying to get sharp shadows using IBL in mental ray and it doesn't seem possible without flickering or super high numbers of Fg points. Testing in Vray we can get nice crisp accurate shadows in a fraction of the render time. They use something called Importance Sampling on the Hdri map to optimize how many and where Fg shoots its rays. Does anyone know anything about this? Does it exist in Mental Ray? Any information would be great.

Thanks

Dawa

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Dawa Fruitman
Animation director

TOPIX
35 McCaul St., Suite 200, Toronto, ON, M5T 1V7
t  416.971.7711    f  416.971.9277

www.topixfx.com

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