Camera motion blur not working if a V-Ray "Still cam" camera is used

V-Ray V-Ray GPU Issues
1

Hi. I’ve noticed that camera motion blur is not working if a V-Ray “Still cam” camera is used. It only works if I change the camera type to “Movie cam”, but there’s another problem with that - if I change the “Shutter angle” parameter while IPR is running, the camera motion blur effect disappears and I have to stop and start IPR every time I want to try out different values. Pretty tedious, especially with heavy scenes that take long to start rendering.

2

Works fine for me, using Max 24.
Though yes, it is extremely tedious having to restart the IPR after literally any change, so
including moving the camera.
This makes it basically unuseable in any practical scenario.

3

No issues on a simple scene. IPR updates the “Shutter angle” fine too. You can send/attach the scene so we can take a look.

4

Here’s a scene where is definitely does not work, using Max 24 and latest Vray 6.
This has setup for both camera blur and object blur, neither of which update.
If you do change the shutter speed then ‘something’ updates but it’s the wrong result :stuck_out_tongue:
As mentioned, simply moving the camera needs a restart.
GPU_MBLUR.rar (47.9 KB)

5

Pardon me, I just noticed we are in the GPU section. Yes, moblur does not seem to update correctly. I’ll notify the project managers about it.

6

Thanks for looking into this. Does it work for you if you use a “Still” camera type? For me it doesn’t work at all with a “Still” camera.

7

Yes, the Still camera is working fine. Have you tried with @fixeighted 's scene?

8

Not yet, I’ve been a bit busy. Will do so as soon as possible.

9

I can’t open @fixeighted 's scene since I use 3ds Max 2023.

10

Here’s a 23 version :slight_smile:
GPU_MBLUR.rar (40.9 KB)

11

Thanks! I found what the issue was. I hadn’t turned on “Camera motion blur” in the Renderer’s “Settings” tab. This is very confusing to me. There’s a “Motion blur” checkbox in the V-Ray camera object, so one would think that this affects both camera and object motion blur since it doesn’t say “Object motion blur”. If it only affects object motion blur, shouldn’t it be renamed to “Object motion blur”? To make matters even more confusing, this checkbox enables BOTH object AND camera motion blur when using the CPU engine and you don’t have to go into the render settings and enable a 2nd checkbox there in order to get the camera motion blur. It’s confusing IMHO.