Alembic from C4D to Maya - Not working

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  07 July 2016
Originally Posted by ugrens: Yes, R17.048 ... imported in Maya 2016 and batch rendered with motion blur with 2D type ... MAC by the way ...
Hope you find solution ... :(

Hey Ugrens,

I actually brought your alembic into Houdini. It has the same sub frame issues. Null or no null the issue remains with alembic files from C4D.
  07 July 2016
You can see that there's some gimbal flips on the animation even looking at whole frames of the cache in Maya, for a few frames the X and Z rotations flip 180. I'm not sure if those are in the source file or not since you didn't include that.

I believe that C4D's Alembic implementation doesn't support subframes at all, I've seen a few threads here on motion blur issues as a side effect of this (do a search in this forum and you should find them).

I guess one thing you could do (apart from letting Maxon know that they need to fix Alembic so that it handles subframes!) is bake the animation down to regular keyframes in Maya and then run the Euler filter on the keys, in your simple example here that fixes it, but of course I don't know if it will work for a more complex hierarchical animation.

Generally with any jobs I've done between C4D and Maya I've always been bringing animation from Maya to C4D rather than the other way around so I don't have any more ideas for now.
  07 July 2016
I can confirm this issue, at least going from C4D to Houdini via Alembic. It seems to get stuck on the same frame every time, although if I use linear keys it doesn't seem to appear. I'm just trying the same setup you described, with a spinning cube. I'm not sure it's related to rotation order, but maybe just a limitation of the Alembic exporter. I'll try a few more things, but the moment it sounds like you're going to need a creative work-around.
  07 July 2016
Originally Posted by aaronbarreras: Just to add my two cents, I tested the scenario you described using R17 along with Maya and Houdini. So far, I'm not able to reproduce the issue you're having, as motion blur seems to be working correctly. I'm not doing anything special, but in trying to follow your example I created a cube, parented it to a null, added a rotation on H, and exported as an Alembic with subframes set to 4. I've tested in Mantra and Arnold and everything seems to be fine. I don't have Vray, so unless the issue is specific to it?

From past experience, however, I can attest that sometimes object hierarchy can screw up how other programs interpret the rotation order. If, for example, you have a lot of nested, or parented objects, that are all keyframed, there may be an issue with precedence (they're all fighting over who rotates first).

To test this theory, take your object and instead of animating it with transforms, try binding it to a single joint and animating it that way. I know that sounds strange, but that's the only way I know to confirm whether the issue is with your scene hierarchy. If it works, then the problem is in how your objects are setup. If it still doesn't work, then it's more than likely a bug or some other limitation.

Just for my own sanity. What is the Shutter Speed or Shutter Angle you are rendering at?

We were at 0.5 in Maya. We have changed to 0.4 and the issues on our test have resolved themselves. We are now doing a larger test with our original animations.
  07 July 2016
Originally Posted by randmcnally: Just for my own sanity. What is the Shutter Speed or Shutter Angle you are rendering at?

We were at 0.5 in Maya. We have changed to 0.4 and the issues on our test have resolved themselves. We are now doing a larger test with our original animations.

In Arnold I'm using the default, 180 deg with a length of 0.5. Mantra is also the default, with no offset. I tried changing these values as you suggested, and it actually makes the problem worse on your sample file.

So it seems I'm not able to successfully reproduce this issue by recreating the scene as you describe, but the Alembic you provided (v03) does render incorrectly for me (on frame 13). Could you possibly post the C4D file you used to create it? I'm curious about any other scene settings in there; framerate, unit size, etc.
  07 July 2016

We have temporarily solved the problem by setting the subframes to four and out camera shutter angle in Vray to 0.4. The combination allows the motion blur to not sample the messed up frames.

Have a ticket in with Maxon now. if there's any more of a fix I will be sure to post here.
  05 May 2018
i got the same problem (animation of cars done in c4d, rendered in maya with arnold)
i tested this issue with many different animations.
And the results that i got are just random, sometimes you get luky and the alembic gets written correctly but if you change anything you get a messed up alembic. it seems that the way c4d makes alembic is really inconsistend and basically broken. Even if you bake the animation and your tracks look perfect you have a chance of getting messed up alembics.

my solution is:
bake your animation, export with fbx, then render in maya with arnold

if you have to use alembic, render with octane or clarisse and the motion blur will looks just fine
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