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Paul Carter avatar image
Paul Carter asked ·

GPU sample clamping

I'm playing with the GPU renderer comparing it to the CPU. I've just done a test with a transparent sphere on a plane with a single area light. I have my sample clamp at 10 for both values. The intensity of the highlight is less with the GPU. Turning off clamp AA fixes it. If the sphere isn't transparent, there's no difference.


A side question on feature parity between GPU and CPU. I've seen the table of Arnold features that are currently supported and those that are not. What about Maya features for GPU MtoA? For instance the CPU supports the Maya solid fractal but the GPU does not.

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Stephen Blair avatar image
Stephen Blair answered ·

Actually, what I see is the intensity of the GPU highlight is less, even without Clamp AA Samples.

What sample settings did you use for GPU?

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Paul Carter avatar image Paul Carter ·

I was using the same settings for both. CPU was 1 sample for everything except camera with adaptive sampling on. Something like 4 camera and 20 adaptive

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Stephen Blair avatar image Stephen Blair ♦♦ Paul Carter ·

@ Try increasing the Indirect Clamp Value, to something like 1000 or 10000

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Stephen Blair avatar image Stephen Blair ♦♦ Stephen Blair ♦♦ ·

Can I ask for you test scene?
I've logged a bug with my own test case, but my test didn't need Clamp AA to get a difference in the intensity of the highlight.

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Stephen Blair avatar image
Stephen Blair answered ·

Maya-specific shaders like Maya Solid Fractal won't be supported on Arnold GPU

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