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Edward Conry avatar image
Edward Conry asked ·

Volume noise is out of control

I've tried everything to get rid of volume indirect and volume. I used aov s to test my scene. And the volume from bifrost vdb can't render with out noise. I have ten lights with four point lights with samples 7 volume samples 6 , a spotlight samples 15 volume samples 7, a directional light samples 8 volume 8, 1 aiphysical sky samples 7 volume 9, 1 aiphysical sky samples 16 volume 16, aisky dome sample 7 volume samples 6, and I set my aa to be adaptive at 10 and my ray depth is all crazy high. I keep increasing the samples but it still has noise. Is it that aiphysical sky don't work with volumes?

mtoavolumesvdb
arnold-volume1.png (338.4 KiB)
arnold-volume2.png (950.5 KiB)
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Edward Conry avatar image
Edward Conry answered ·

I clamped the aa samples and that removed the noise. Thanks

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jack frost avatar image
jack frost answered ·

I can second that. Same as I described there https://answers.arnoldrenderer.com/answers/24201/view.html

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Lee Griggs avatar image
Lee Griggs answered ·

Is there a light inside the volume (intersecting with geo) that could be creating the fireflies?

How are you driving the emission? With a blackbody?

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Edward Conry avatar image
Edward Conry answered ·

Ok I think I figured it out. It's the emission on the volume shader. I'm thinking that to increase the sampling of the emission it's a lot like a mesh light, just alot of aa samples.

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Thiago Ize avatar image
Thiago Ize answered ·

I'll let others comment on why that specific noise (the fireflies?) is there and how to get rid of it.

You might already have done this, but make sure to download and install the latest version of Arnold in case it fixes this problem or improves some other related code, such as the adaptive sampling.

What can generally help when you have noise that isn't easily solved is to take the brute force approach. Lower all your samples to 1 (lights, diffuse, volumes, etc.), set your camera AA to 4, set your max camera AA to something large like 40, and enable adaptive sampling. Hopefully this will allow the samples to go where it's most needed.

Another thing to try is to clamp AA samples and/or lower the indirect clamp value (look under Clamping).

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