Motion blur causes mystery streak across image

[AardmanCGI]

Hi,
We have a scene which is giving us serious issues due to a mystery streaking that is appearing at random frames in the sequence. It only happens when motion blur is on and doesn't appear directly related to anything happening in the scene.
Here is an example:

And here is a simple Maya file which shows the issue:
vrayMysterySteakIssue.mb.zip

It happens on many frames but not all. Frame 70 is a good example.

Please help!

Thanks.

[vlado]

Thanks for the scene, will check it out.

Best regards,
Vlado

[Morbid Angel]

I'm not sure how your geometry is being cached, looks like some kind of bake? it appears that some objects like sts:m_sticker_GEO have key animation in each vertex? I could see this being an issue. Is there any reason you have it cached this way? I would suggest try point caching the geometry instead, this should fix your issue.

[vlado]

Can you tell me which Maya version you are using? A quick test in Maya 2013 on frame 70 doesn't show the error; I will let a few more frames to render to see how it goes.

Best regards,
Vlado

[Morbid Angel]

it was 2013 also for me 2.25 build.

[AardmanCGI]

Thanks for the replies.
It was Maya 2011 that we are using. Vray 2.25.01-20120831

The caching in this scene is simply baking all motion to points so that I could make the scene self-contained. There is nothing unusual about that. The problem also occurred before I baked the animation so it's not related to that.

[vlado]

Ok, wil try to render with Maya 2011 and that exact build. So far rendering in Maya 2012 and 2013 and the latest nightly does not produce the streak. Btw, can you tell me the machine specifications (number of rendering threads) too?

Best regards,
Vlado

[vlado]

Hm, I wonder if this might have something to do with the batch mode... I have to check that too.

Best regards,
Vlado

[AardmanCGI]

Hi,
This streak appears in batch mode and in normal mode.
It is consistent across different hardware as well. For an example my computer is:
OS: Linux 2.6.32.26-175.fc12.x86_64 x86_64
System: Fedora release 12 (Constantine)
KDE: 4.4.5 (KDE 4.4.5)


Processor (CPU): Intel(R) Xeon(R) CPU E5540 @ 2.53GHz
Speed: 1,596.00 MHz
Cores: 16 (8 physical Hyperthreaded)

[AardmanCGI]

correction

In case you get an email notification with my last post - it had a typo in it which said that the streak only appeared in batch mode. This is not the case - the streak appears in all modes. Have corrected the original post now.

[vlado]

Thanks, I can reproduce the issue now; looking into it.

Best regards,
Vlado

[vlado]

This seems to be related to the subdivision surfaces; it doesn't happen in the 3.0 builds, but I'm still trying to figure out what fixed it.

Best regards,
Vlado