You don’t need to change much, if anything, if a scene is simple. But with complex scenes (interiors, exteriors), there often are a lot of things that need to be readjusted to make them render the same. Bump map and normal map strength values are very different between CPU and GPU. The bump and normal textures themselves also often need to be different too, because CPU requires much sharper textures. Alternatively, you can use the same bump and normal textures but you’ll need to set their Blur amount to 0.1 - 0.01 in order for them to appear the same as GPU. The latter is not a good solution though since low texture Blur amounts leads to longer render times. There can also be differences in light intensities with dome lights with HDRI textures. VrayBlendMtl doesn’t work the same. 2-sided and SSS materials will also render a bit different. Etc. etc.
I’ve just realized the images above are not very clear. Here are a couple of new ones that shows things better. BTW, I haven’t changed the lights’ colors and intensities, nor the bulb material settings.
Yes, very simple scenes won’t show much difference between CPU and GPU, if any. It’s more complex scenes when things start to fall apart. What do you mean by “Post the lamp/light” ?
I meant upload the lamp mode and light only, so that will keep whatever render setting are in the main file, so it’s easier to spot anything odd in settings e.g.
It’s hard to believe that simply the scene having other objects in it would cause this, however you could very simply test that theory if you delete everything
other than that lamp and see if it renders as expected
Yes, as I already mentioned on the previous page, turning off or deleting all other lights except for the one in the table lamp fixes the issue with the refractive materials. So not much sense in uploading just the lamp model and its light - this will render fine in such simple scenario. Of course, deleting all lights except the table lamp light is not a realistic solution to the problem for me since I need to have proper lighting in the interior.
Below are a couple of new screenshots that show what happens when I delete all lights except the one in the table lamp. The glass bulb renders properly with GPU in this case. Interestingly, now I see another problem with GPU happening. The light’s color is way off and some purple noise appears when I use Light Mix. Both images below have Light Mix turned on and the only thing changed there is the light’s color from 6500K to 4000K, so nothing elaborate or unusual in terms of settings.
Are these IPR screenshots?
I know that GPU doesn’t update properly when changing settings, so can give weird results, needing a a restart after changes.
In any case, support has your file, so maybe they can discern what is happening, as
I built a scene with a bunch of lights to sort of mimic yours but I can’t get it to misbehave as yours is…
Both are IPR, but I have not changed any settings after starting IPR. BTW, for me it’s the other way around - GPU IPR updates a lot more changes than CPU IPR does which is a bit strange. One would expect it to be the other way around given that the CPU engine is more feature rich and is given more attention to. Sometimes I miss this flexibility when using CPU rendering and I find myself restarting its IPR more frequently for changes to take effect.
Any updates on this issue? Do you think this can be fixed for the release of Vray 6? I would love to use Vray GPU, but unfortunately can’t because of this bug.
Hi, @Muhammed_Hamed . I was wondering if this is still being looked into. Do you think a fix can be implemented in the new updates or is it a more complex issue?
Hey Alex, sorry about that. it is taking time but will get fixed in the near future.
We will have a meeting next week over that. I know how important this fix is
That’s a very costly workaround which slows down the rendering a lot and creates fireflies. It nullifies that reason to use GPU. Also, it’s not just the darker reflections. It’s also problems with wrong light intensity when refractive materials are used.
Completely disabling the option made alot of fireflies in my scene but setting it to 200 didn’t make any and i think it didn’t raise my time or raised very little that i didnt notice
Hi,
Lights are still buggy with GPU rendering in Update 1. Lights behind refractive objects still lose their intensity when there are many lights in the scene. When is a fix expected? I bought an expensive graphics card with the intent to use Vray GPU, but unfortunately I still can’t do so due to this major bug.
Hи, thanks for posting. The issue is not resolved yet. If you’d like, please send us your scene so we can try to find a workaround until the fix is ready. You can do that here or using our support contact form.
Lights behind refractive objects still lose their intensity when there are many lights in the scene. When is a fix expected? I bought an expensive graphics card with the intent to use Vray GPU, but unfortunately I still can’t do so due to this major bug.