Hybrid rendering - specular and reflections pass quality

[Szakul]

Request to Admins: Please move this topic to V-Ray GPU or V-Ray Sketchup. I don't know why, this forum is one of a few where I have +New Topic button. Sorry for inconvenience.

Hi. Quickly question about differences between bucket rendering (CPU - V-ray Adv) and Hybrid rendering (CPU+GPU V-ray RT). Overall both final renders looks similar. Image rendered with CPU only (bucket) has more details in specular, reflections and lighning pass. Especially specular pass looks much much better. On Hybrid specular is very flat. Is it normal behavior or should I change something in my shaders to achive similar specular pass on both renders? Light in the scene - SUN/SKY. V-ray 3.6 for Sketchup. Graphic Card - GeForce 1080Ti. Thanks for help.

[georgi.georgiev]

Hi,

Please note that CPU and GPU render engines are completely different and could produce distinguishable render outputs, depending on the scene's set up. It is advisable, when starting a project, to choose one specific render engine and stick to it throughout.

In respect to the differences for this particular case, it is possible they occur from the material's settings and/or the material uses legacy plugins. Additionally, please be informed that some features are currently not supported by the GPU engine. You could check the full list from the following link - https://docs.chaosgroup.com/display/...orted+Features

[savage309]

Comparing two different render engine 99.9% of the time will give different results. It might not be the case of “currently not supported”, but also be the case of “using shaders from another render engine”, aka not intended to work. The UI should not allow you to create shaders from one of the engine in the another (V-Ray GPU in V-Ray, and vice versa).

Best,
Blago.

[Szakul]

Sorry for delay. I couldn't answer because of weird problem with forum, but support helped me to fix it. Returning to my post. I found where was the problem. The problem was in a bump map - which was a noise B map. After change to normal map with texture (very similar to noise map) everything looks perfect.
I found other problem. Bump map rendered with GPU looks always identically. No mater if amount is 1 or 0,1. It always looks like 1. Preview and CPU rendered bump map is correct.

[Peter.Chaushev]

The bump amount GPU discrepancy is resolved in V-Ray Next for SketchUp.

Kind regards,
Peter