Motion blur messing up with changing geometry

[mumle]

I have a project where I use the slice to remove some excess geometry while animation happens to it. But it behaves rather unfortunately.

It will either not render MB or render it wrong. If I increase samples it just adds another object.

If I disable the slice, it looks correct. If I render with CPU, it is fine.

An overall experience, if the samplerate is at anything but 2, it tends to give issues in motion blur.

[mumle]

Here is an example of the scene. It shows the part with MB and no MB
https://www.dropbox.com/s/r3821tbaxf...issue.max?dl=1

[fixeighted]

I found this old post which seems to suggest it is simply not possible to achieve mb with slice. https://forums.chaos.com/forum/v-ray...er-motion-blur
Vray clipper seems to work just fine, so that could be your solution here

[mumle]

I found this old post which seems to suggest it is simply not possible to achieve mb with slice. https://forums.chaos.com/forum/v-ray...er-motion-blur
Vray clipper seems to work just fine, so that could be your solution here

The "problem" is that with CPU it works fine.

[mumle]

And the way the geometry samples behave, i dont understand.
It is not in this example, but I have other cases where an object goes to rest and the MB explodes for a frame.

[fixeighted]

Sorry but I found that with cpu the issue is the same, so not sure what could be the issue otherwise.

[hermit.crab]

Use the VRayClipper as mentioned in the old thread. Motion blur and the Slice modifier do not work well together (changing topology).