Major Motion Blur Issues

[sam_wickert]

I have been facing multiple vray 6 (3ds max) motion blur issues with scenes involving motion blur on vehicles with camera motion blur when using GPU rendering. Motion blur will either be exaggerated, or incorrect completely.

Also, geometry is popping with the motion blur and is affected on certain frames.

Videos of the issues can be found here: https://www.dropbox.com/sh/sxgjsylao...I_z9HtXva?dl=0


Here you can see exaggerated motion blur that is continuous (and shown in the videos)

Has anyone faced these issues?

Motion blur seems to corrected when rendering CPU.

[vladimir_krastev]

HI what video card are you using, what is your driver version, what is your 3ds max/v-ray version? I watched the videos but cant really tell where are the issues. Could you share a CPU render of the same shot so we can compare in greater details?

I have been facing multiple vray 6 (3ds max) motion blur issues

Does that mean that the animation you've sent renders differently in V-Ray 5 regarding motion blur?

[sam_wickert]

I have confirmed I'm also facing this issue in Vray 5. Ive attached a scene that shows the first half rendered with the gpu then the second is CPU. Same scene... you can see how the motion blur is handled much differently and correct with motion in the CPU, but not on the GPU. https://www.dropbox.com/s/tn2p74lgbs...ndCPU.mov?dl=0

Its almost as if, even though the camera moves with the car, Vray is acting as though the motion blur is there for if the camera was moreso stationary.

Madcar plugin is being used for the car animation, but I've also tried baking animation to keyframes to see if it would fix the issue -- currently no luck!

[sam_wickert]

HI what video card are you using, what is your driver version, what is your 3ds max/v-ray version? I watched the videos but cant really tell where are the issues. Could you share a CPU render of the same shot so we can compare in greater details?



Does that mean that the animation you've sent renders differently in V-Ray 5 regarding motion blur?

as for the GPU -- nvidia 3090. 3ds max 2021/ vray 6 hotfix2

[vladimir_krastev]

Hi I tested a similar setup. The camera moves together with the box but also pans a bit around the text.

http://ftp.chaosgroup.com/support/sc...9_18-03-39.gif

Left is CPU, right is GPU. I see no difference so it looks like it is something specific to your scene that is causing differences.
You could send it for review if you wish. Use the support contact form or just attach it here.

[sam_wickert]

Please do take a look... can't seem to figure this out... I've attached a link to a simple version of the project with the needed assets to see. https://www.dropbox.com/s/omq0i710sf...sting.max?dl=0

When scrubbing around frame 95 you will start to see the error in motion blur.

[sam_wickert]

In order to see the issue, you need to render out a sequence.. the first GPU single image is correct, then the second after will be incorrect (as well as every frame after that).

I rendered out frames 90-95 on CPU and GPU... here's the result of frame 95...

[vladimir_krastev]

Hi sam_wickert

Our highly skilled colleague tashko.zashev was able to trouble shoot the scene and found out that if we have movie camera (V-Ray Physical camera) with a negative Shutter offset value (as in your scene) this leads to the wrong motion blur effect as seen in your examples.



The issue reproduces in a simple scene.
The issue is logged as a bug under VMAX-12573.

[sam_wickert]

So glad you figured this out! Thank you! Looking forward to having this fixed in future releases as well!