Motion blur not working

V-Ray GPU V-Ray GPU :: Issues
1

Hi,

I am using the new V-Ray GPU 6 Update 1 version, but the Vray camera motion blur is not being rendered by the GPU.
With the previous version everything rendered fine.
Is this already mentioned?

Leslie

2

Nobody else is having this issue?

3

Works fine on a simple scene. Note that camera motion blur is supported only on integer frames and shutter efficiency is also not supported. You could attach (or send) the scene so we can take a look.

4

Hi Alexander,

I have send you my test file.

Leslie

5

I received the scene, however, I don’t know what I’m supposed to look at. There’s no animated camera in the scene (check docs regarding camera motion blur). Please, share screencaps/videos of the reproduction method and a comparison between CPU and GPU to continue investigating.

6

Last week when I was rendering this scene with the CPU, I got correct motion blur of the moving truck. (truck is moving and not the camera) If I use the GPU settings there was no motion blur at all. Last week I bought a new GPU (4090) and I am now rendering the scene again and everything works fine! :roll:

7

Hi guys,

I’m trying out Vray GPU rendering for the first time in production and I’m not getting motion blur on my confetti simulation that was imported from Houdini as an alembic. I tried importing the alembic through a vray proxy and also just a regular import and there is zero motion blur when switching to gpu rendering. CPU rendered the motion blur perfectly. The object has deforming geometry with point and face count fluctuating. I know some render engines don’t support motion blur on deforming topology (like corona) but is this the case with Vray GPU?

Please let me know if you have any info on this.

Thanks!

8

Have you exported a Velocity channel from Houdini? I did a quick test with an object with deforming geometry and GPU (exported as .abc) - seems to work as expected.

9

Hi Aleks,

Thanks for getting back to me. Indeed the velocity is there, the motion blur works in max perfectly when using vray CPU rendering. I’ve uploaded the .abc here. Would you mind taking a look to see if it works on your end?

Please let me know if you can get it working.

Thanks again,

RS

10

Sorry I should point out that the simulation starts at frame 250. Strongest motion blur should be seen in the first 5 frames

11

Are you using a VRayProxy to load the .abc? Motion blur (both from the Settings and Camera) works fine on both CPU/GPU, although the results are slightly different. Play around with the Motion Blur duration / Shutter Speed.

12

Do you mind sending me your max file so I can have a look through? I tried proxy and the camera settings in the settings tab but I’ve not been able to see any motion blur using gpu rendering.

Thanks again for the help!

13

I’ve uploaded a max file here. I was actually using the alembic file imported directly into the scene and it was working fine with cpu. Then when I merged in using a vray proxy I couldn’t even get motion blur using the proxy. Sorry I’m not 100% on this .abc workflow yet. If you don’t mind could you take a look at my file and spot what I’ve done wrong?

Thanks!

14

Solved! Human error, I forgot that .abc files needed to be imported through a vray proxy and discovered that the velocity is calculated very differently between the 2. In houdini I scaled the velocity to suite the render using an imported .abc file and cpu rendering which looked fine. I fixed this by scaling the velocity in houdini appropriately and importing through a vray proxy.

Thanks for the help! Sorry I was doing it so wrong… My bad!