Poor Results

[glorybound]

I am using GPU progressive, and the results are not good. Here are the renders. They are 4K, with a noise threshold set to .003 and .005 for the light cache. Zoomed out, they aren't bad, but zooming in, they fall apart. As you can see, I have turned off the denoiser. How can I try to fix this?

[Joelaff]

I am by no means an expert when it comes to GPU, but have you increased the Max number of samples? If I recall GPU has a default samples limit that is too low to actually achieve the noise threshdolds you are using. I seem to recall the logs saying something like Rendering terminated because sample limit reached, as opposed to continuing under the noise limit is reached. It looks like undersampling with denoising.

[Muhammed_Hamed]

Hey Bobby!

Increase the samples limit to 5000, and GPU LC Subdivs to 3000. Maybe noise threshold of .01 and Intel's denoiser
What are the render times?
And do you see any errors in log? what about GPU memory usage during rendering?

Best,
Muhammed

[Joelaff]

Have you guys considered increasing the default sample limit for GPU? Not sure I understand the motivation behind it being so low. In CPU there is no such limit, other than max subdivs.

[Muhammed_Hamed]

Have you guys considered increasing the default sample limit for GPU? Not sure I understand the motivation behind it being so low. In CPU there is no such limit, other than max subdivs.

It has a big impact on render times depending on the scene, hence we decreased it from 5000 to 2500 in V-Ray 6
2500 is a good starting point, and should be doubled then tripled if the user wants a cleaner result
The standard V-Ray CPU works in a different way, and will not be as slow if you use high Max Subdivs

[glorybound]

When I raise it that high, I am at CPU render times.

[glorybound]

Hey Bobby!

Increase the samples limit to 5000, and GPU LC Subdivs to 3000. Maybe noise threshold of .01 and Intel's denoiser
What are the render times?
And do you see any errors in log? what about GPU memory usage during rendering?

Best,
Muhammed

I'll be playing more with the settings when the client has feedback.

[glorybound]

Okay, super clean in 15 minutes using your recommended settings.

• Samples limit 5000
• LC Subdivs 3000.
• Noise threshold of .01
• Intel's denoiser

Thank you!

[Muhammed_Hamed]

15 minutes for this kind of scene in 4k is impressive!
Thank you for sharing! I will update the documentation about sampling for GPU, it could be better

Best,
Muhammed