GPU - bump MUCH stronger than CPU

V-Ray V-Ray GPU Issues
1

Hi Guys

I understand the typical copy/paste response from ChaosGroup in these situations:
“Please note that CPU and GPU are completely different engines. We recommend, when you start a project to chose what type of engine will you use in the beginning and use that through the whole project.”

…but this isnt a slight variance, this is a major different look.

On cpu, with a bump multiplier on a simple jpg texture of about 30, to get similar look on GPU, I have to lower the multiplier to about 0.05. The bump is so strong on GPU, that it even changes the colour of elements to much darker than what it should be (if I switch of bump, then the colour returns like it was when using CPU) Is this expected behaviour? Is there an INI or system wide setting I can adjust somewhere, so I dont have to adjust materials made over the past few years.

Alternartively, is there a know multiplicaton factor I can use in a script to change all my materials one shot?

2

i have flagged this before and receved the generic response. i was going bonkers trying to work out why all my purchased assets looked awful, even though they had basic materials applied.

you’d think that normalising bump levels, at least approximately, between cpu/gpu would not be impossible for the coding wizards who brough us vray. . certainly it should be possible to get closer than 20+ times stronger.

3

I’ve noticed this too!

4

Same with me as well.

5

Do you also have lighting differences with the same setup?

6

Didnt notice this much, but probably only because GPU I also switched on auto white balance and exposure
I thought I was going nuts because a lot of my scene did seem way darker in GPU than CPU, but as soons as I switch off all bump from materials the scene looked almost identical to CPU. It wasnt the lighting, but the beauty of materials were too dark because of too strong bump. From there I switched the bump back on and heavily decreased the multiplier. Feels like a bug to me to be honest, but for now I’ll use this workflow of having bumps at 0.01 and 0.05 while using GPU

7

This is not the case in other Vray plugins, Maya/Houdini/Modo
Bump is almost the same strength in my testing here between CPU/GPU and your argument make a lot of sense
So I hope devs could do something about this

8

yeah I noticed this too.

but I am also having lighting differences.

9

I got an email from Support group and they confirm about the lighting difference issue with HDR with render multiplier different than 1 and/or intensity set to grey.