Wrong Motion Blur Direction with moving PRT Volume

I did a short test with an moving PRT Volume using motion blur.

While I was surprised that it worked in the first place (have not thought it would be possible) I noticed some strange behaviour on the particles.
In contrary to the moving direction of the object the blur seems to be traveling inward (to the rotation center) not along the rotation axis when the object is aligned to the Z axis.
(Watch video frame by frame)

Moving (not rotating) objects seem to be rendered fine.

See attached video and file :wink:
MB_Objects_01.zip (67.4 KB)
MB_Object_01.mov (430 KB)

I can confirm that there is indeed a problem - especially obvious when rendering from top down. When the box is vertical along the Z axis, it has velocities moving vertically too. Logging

I did another test to see how other axis behave with MB

In the attached test:
X = Red
Y = Green
Z = Blue

MB_Particle_01.mov (2.93 MB)

It seems like the only plane working at the moment is the XY as it produces strange results on XZ and YZ.

I also attached the scene :wink:
Not that I had to cache the particles as they produced MB errors without caching (I guess due to particles dying in sub frames)
This issue might have something to do with the Z-Axis inversion?

Cheers,
Raphael
Directional_MB_01.zip (77.4 KB)

Yes, we suspect the Z axis problem that is plaguing the current BETA 4 is in the root of this, but we could not fix it before posting the build and we did not want to hold it back. Next week we will try to clear all transformations everywhere in the code and hopefully we will get this fixed soon.

Thanks again!

Sorry I´ve been living in the past… I have made the tests with the old beta from the 8th of january.
I will update the tests with the newest version :blush:

EDIT:
I have been running the Test again and the wrong alignment of the MB seems to be gone! Thanks a lot for this improvement!
Sorry again for the confusion. I have not been notified about a new version so I was still testing the old one :blush: :blush:

Cheers,
Raphael

best thing to do is go to the “Krakatoa C4D Builds” and at the bottom of the page, click “Subscribe Forum”
That way you’ll receive an email whenever there’s a new version (or post) :slight_smile: