topic Re: Volume rendering with GPU vs CPU in Arnold GPU Forum

Volume rendering with GPU vs CPU

Steve_Watts_Kennedy — Thu, 27 Feb 2020 11:52:10 GMT

I'm testing out Arnold for a project which will require a lot of volume rendering. Ideally would like to be able to do it on GPU. I've created a test scene using the WDAS cloud, following https://docs.arnoldrenderer.com/x/2IaMB

I've rendered out a frame using CPU, and then GPU. The only difference between the two is the device.

The CPU frame looks great, the GPU one looks pretty bad:

Is this a limitation of Arnold GPU? Or is there some additional setup required for rendering volumes on the GPU?

Re: Volume rendering with GPU vs CPU

Steve_Watts_Kennedy — Wed, 11 Mar 2020 21:18:38 GMT

No-one knows what’s going on here? Am I the only one trying to render volumes with Arnold GPU?

Re: Volume rendering with GPU vs CPU

madsd — Wed, 11 Mar 2020 22:09:35 GMT

I just downloaded the asset and tried in more recent build released ( earlier today )
In my case, the CPU is the dark and the GPU the bright.

So yes, this should get a ticket in some system somewhere, but I think it's already there, it just hasn't been executed.

Re: Volume rendering with GPU vs CPU

Stephen.Blair — Wed, 11 Mar 2020 22:27:54 GMT

We already have a ticket and it looks like a reasonably easy fix to make the GPU match the CPU.

Re: Volume rendering with GPU vs CPU

James_Grimes — Wed, 18 Mar 2020 22:20:11 GMT

Are there plans to open up the samples settings (i.e., diffuse, specular, transmission, SSS, volume indirect) for Arnold GPU in the near future?

I am having a difficult time reducing noise levels in my GPU renderings to match those of my CPU renderings. I adjust my settings according to the Arnold documentation (i.e., increase camera (AA) and use adaptive sampling). However, the setting levels necessary to match the CPU render quality cause my GPU renders to take nearly as much time to render as the CPU. If we were able to target the source of the noise and adjust the appropriate sample setting (e.g., diffuse only), our GPU renders may be able to achieve CPU quality with faster rendering times.

Re: Volume rendering with GPU vs CPU

schwungsau — Fri, 20 Mar 2020 04:03:35 GMT

you should ask this question Nvidia, its not supported in optix yet.

Re: Volume rendering with GPU vs CPU

Anonymous — Fri, 27 Mar 2020 17:26:13 GMT

Yes, I also cannot get clean image with gpu. I think for now the only solution is to denoise it in After Effects... This time we got donkey in a bag from nVidia and Autodesk...

Re: Volume rendering with GPU vs CPU

Stephen.Blair — Tue, 28 Sep 2021 13:11:53 GMT

This was fixed in Arnold 6.0.3
https://docs.arnoldrenderer.com/display/A5ARP/6.0.3.0

7878 [GPU] Discrepancy in volume rendering when scatter_color components are large