Volume rendering with GPU vs CPU

[Steve_Watts_Kennedy]

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?

[Steve_Watts_Kennedy]

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

[madsd]

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.

[Stephen.Blair]

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

[James_Grimes]

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.

[schwungsau]

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

[Anonymous]

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...

[Stephen.Blair · Accepted solution]

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