Drastically different results using hybrid CUDA vs CPU - Render Settings Issue

[gfmarsh]

Just wondering if hybrid CUDA rendering is at a beta stage still/ I am get drastically different results from a VrayMTL using some procedural 2d and 3d texture nodes piped into it (Granite, Noise, and Ramp). Basically the CUDA method gives me the result I want but the CPU does not. Hybrid CUDA does not work with CPU render farm rendering, so I'd like to get the same result with CPU method. I am also repeatedly having to reset my Maya prefs as often I can't pull up the render settings. Thanks in advance.

[savage309]

V-Ray GPU is different render engine to V-Ray CPU. Results often will be quite close, but the idea is not to have 1:1 match.
To enable the Hybrid, either use the "ocldeviceselect.exe" tool that comes with V-Ray and check the "C++/CPU" device on each node, or add env var "VRAY_OPENCL_PLATFORMS_x64=c++/cpu;nvidia"
After that, start CUDA rendering.

Best,
Blago.

[gfmarsh]

Hmmm...they don't seem to be close at all. Here are the results. Hybrid is enabled as I believe I did the ocldeviceselect.exe quite awhile ago, otherwise I would not have the render option checkboxes as shown. The reflection is coming from the light dome tex as show in the Hybrid version.

I forgot to mention that my image plane from the camera disappears as well in Hybrid renderer.
Thanks

[Morbid Angel]

its most likely the particular procedural used in the left image is not supported by the gpu.

[savage309]

Yes, check the supported textures in CUDA(Hybrid) here https://docs.chaosgroup.com/display/...orted+Features

Best,
Blago.

[gfmarsh]

That document states that noise, ramp and granite both work on the CPU and Hybrid GPU, maybe you can't combine them. In any case it is the second image on the right (Hybrid) that I am after.

[savage309]

Granite has footnote in the docs , please check it
It might be easier just to forward the scene to support@chaosgroup.com for investigation. Either way, don't expect CPU to render the same as GPU(Hybrid). They are different engines, sharing the same UI and mostly the same features.

Best,
Blago.

[yolov]

I initially thought the comparison is between CUDA CPU (i.e. cuda c++) and CUDA, but if you're seeing the camera image plane in one render, then it must be the CPU (non-cuda) render. The CUDA render does not support camera image planes currently. So that might be something to keep in mind for the moment.