GPU + Displacement = Bad

[JesL]

I've been aware of the differences in potential results with displacement when using the CPU and GPU in the past years since GPU was implemented. Having upgraded to V-Ray 5 with Rhino 7, I was hoping there would have been some progress made, but am disappointed. I can understand there might be some settings I'd have to adjust between CPU and GPU to achieve similar results, but the frustrating thing is there doesn't seem to be any good official explanation on how to achieve any kind of consistent, predictable result with displacement/GPU. Things like UV mapping issues and displacement texture pixelation are constant issues for me with GPU, when everything looks great with CPU and the exact same settings.

It would be nice if there was more information from Chaos Group with regard to differences between CPU and GPU displacement, but I haven't really been able to find any specific info on how settings might need to be changed or how you should approach differently. I've tried trawling forums for info, but the only thing I seem to ever find is "Please send the scene" and no useful information coming after that.

With how slow displacement is in V-Ray, it's also frustrating I can't use Chaos Cloud to free up my machine in these instances because of issues with GPU displacement, which is further slowing me down with work (which in turn is probably the cause of my exasperated tone, which I apologize for).

Just blowing off steam I guess, but if anyone knows of any resources for reliable info on this subject, I'd very much appreciate.

[konstantin_chaos]

Hi JesL,

Things like UV mapping issues and displacement texture pixelation are constant issues for me with GPU, when everything looks great with CPU and the exact same settings.

We recently realized that the pixelated textures caused by GPU Engine when a displacement map is applied to an object are caused by the On-demand mipmapping of textures.
You can disable the option from the Advanced Settings Panel / Render Parameters / GPU Memory management / Resize.
Selecting full-size textures will most probably resolve pixelated or blurry texture issues.

It would be nice if there was more information from Chaos Group with regard to differences between CPU and GPU displacement, but I haven't really been able to find any specific info on how settings might need to be changed or how you should approach differently. I've tried trawling forums for info, but the only thing I seem to ever find is "Please send the scene" and no useful information coming after that.

We'll consider adding more information about GPU rendering and Displacement on our documentation page.

...which in turn is probably the cause of my exasperated tone, which I apologize for

It's actually good to bring such things to our attention!
Do not hesitate to do so in the future.

Regards,
Konstantin