Motion Blur corrupting textures.

[sebbiej]

When I attempt to render with V-Ray GPU in Maya 2022 with motion blur enabled, some of the textures in my scene go all corrupt and unusable. How can I fix this? I need this to be fixed as soon as possible due to tight deadlines. I've had this issue before with GPU, whereby textures can go all glitchy when objects or the camera is moving and motion blur is enabled.
I really need to be able to use motion blur and the speed of GPU with this project.

Examples below of how the texture is going wrong:

I'm using the latest version of Vray, 5.20.02 (downloaded today).

[frame48]

Same issue here, problem goes away when either turning motion blur off or switching to cpu.

[Martin.Minev]

Hi,

Could you please send us the scene files with the assets using our contact form here. We will need to investigate what is causing the issue.
Please mention this thread in the email.

Thanks!

[sebbiej]

I thought it'd be best to post up the result of Chaos looking into it, in case anyone else has the same issue. Thank you very much to the devs for taking a look into it.

After further investigation here is what we found.

The issue is present only with the following conditions on moving objects:
- Use of Viewport subdivision or Subdivison attribute on the geometry instead.
- Motion Blur is active.
- V-Ray GPU used

In other words, if you remove the Viewport subdivision option from the render settings (since your meshes have a good poly count) you should be able to render your scene without any issues. Please, find the image useful: http://ftp.chaosgroup.com/support/sc...6_10-08-58.jpg

This was reported as a bug and it would be most probably be fixed in future updates. For now, as a workaround, you could manually smooth and add additional polys to your meshes.

frame48 I hope this can help you too.

[frame48]

Thank you sebbiej! Yeah we had to fully ditch Vray GPU from our pipeline, it's quite a bummer that this still hasn't been fixed. Destructively smoothing a mesh in order to work with GPU doesn't seem like a viable workaround, specially when working with a lot of displacement maps.

Martin.Minev Is there an ETA on when this fix is coming?

[Muhammed_Hamed]

Hello frame48 ,

Sadly this is not an easy fix, this topic has been brought up multiple times recently with the development team, it is near the top of the current priory list. I will update the thread when we have news on that

Best,
Muhammed

[david_enedy]

Muhammed_Hamed Any news on this being fixed? I just ran into this issue.

[peter_hoehsl]

Any updates on this? I'm in Houdini and textures are missing on RTX when motion blur is switched on. Most annoyingly the issue isn't consistent and will happen randomly with the same unchanged scene. Also why does one GPU in a two GPU setup always use almost exactly 2x as much VRAM as the other one? Is it related?

[peter_hoehsl]

Update: After some trouble shooting I discovered that in Houdini (Linux) the presence of a Cd attribute (color) on my geometry messes up textures / uvs or renders the object completely black on GPU when moblur is switched on. This happens regardless of whether the Cd attribute is used in the shader or not. I have mentioned in another thread that color info was discarded when used in the shader without textures and combined with motion blur. A fix would be nice.