I'm getting inconsistent Motion Blur when rendering a Cloner baked into an Alembic file.
How it was made :
1. Run Pyro sim
2. Use native C4D Field Force for X-Particles emitter advection
3. Use X-Particles emitter's "generate Thinking Particles" to export particles as an Alembic file
4. Import that Alembic file into a new scene and clone spheres onto it's points using Fields for more precise control compared to what's available in XP
5. Drop that Cloner into a Connect object and export that geometry as a new Alembic file
When rendering the final Alembic file I'm getting Motion blur on some frames but not others. What's strange is I can only get motion blur on every frame if I use a Length of 1 ( for 360 angle ) and only when choosing the Position as either Start-on-Frame or End-on-Frame. Center-on-Frame will render some frames with Motion Blur but not others.
Changing the Length to .5 ( for 180 angle ) gives the same inconsistent results regardless of Position. Changing number of Keys has no effect. Disabling "Re-run simulation in each frame" also has no effect.
Using the motion vectors AOV also doesn't produce a working AOV for this shot.
It's clear the velocity data is there but can't get it to work consistently. I would just use the RSMB plugin in AE but it's not working on this shot.
Any help would be appreciated.
Edit : Found a workaround. To get a 180 shutter manually set the Start to 0 and End to 1 in the global render settings for a full 360 shutter. Then on the camera add an Arnold tag and clamp it using Start 0 and End 0.5. It's like the velocity data randomly switches which half of the frame it's on and setting the global setting to 0-1 forces the full range to be read before clamping in the camera tag. The documentation isn't clear so this is just a guess. Either way it produces the desired result.
