Alembic cache import missing frames

I am exporting my character animation as alembic cache files from Maya 2016.5 and importing them into UE4 as geometry cache files.

For the most part, everything works fine. However, it seems that very certain frames would not play back in UE4 despite having checked to be working fine when importing that same alembic cache back into Maya.

For example, I am exporting an animation sequence that goes from frame 1-1000 in three parts (frames 1-300, 301-600, 601-1000). Frames 1-300 would work perfectly fine, but in the file that contains frames 301-600, the imported geometry cache would only play from frames 500-600, completely skipping 301-499. Finally, the file that contains frames 601-1000 would not play any animations at all and hold on the frame 1000.

I have checked that all these files play fine when imported back into Maya, and they all use the same alembic cache export/geometry cache import settings. I have also experimented with baking the animation before exporting, using different settings, using different computers, etc with no avail. Seeing as how they work fine in Maya, I believe this is an UE4 issue.

If I try exporting the entire frame 1-1000 as one large file, the animation would work for the most part, but there would be glitches/bugs in certain parts, where pieces of geometry would skip ahead from the rest, play animations that were never put in (ie, blendshapes that were not turned on would play when imported as geo cache), etc.

I understand this is a bit of a complicated situation. Please let me know if you want any clarification/more information.

Hi ,

Could you provide repro content so we can take a look?

Cheers

Jurre

Hi Jurre,

I’ve uploaded one of the character’s animation alembic files to this dropbox: Dropbox - File Deleted - Simplify your life
The files are broken into the different geometry pieces of the character (eyes, mouth, body, and gloves).

If you import them into Maya, you should see the animation playing from frame 346-920, however, if you bring it into UE4, the animation should start from roughly frame 570 and not play frames 346-569.

I’ve attached screenshots of my export/import settings as well as the Maya and UE4 viewport. For the alembic export settings in Maya, I found that UV write, write face sets, and world space are essential to keep the animation and models of the character in tact, and renderable only, strip namespaces and whole frame geo make no difference (or at least do no harm) so I kept them on. I’ve tested that having them off makes no difference for this issue.

Thanks!

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Any updates to the issue so far?

In the mean time, I’ve found a work around to this issue. It seems, as long as the animation that is being cached out from Maya starts at frame 1 and is within a few hundred frames, everything works perfectly fine. This explains why frames 1-300 in the initial example worked fine, and the rest of the frames had issue.

To put this to an example, in Maya, I would move all the keyframes in the scene from frame 301-600 to start at frame 1, thus making it frames 1-300. The same for frames 601 to 1000. Just move the keyframes to the left of the timeline to start at frame 1 and not frame 601. It is very strange why this works, and is cumbersome to do, but gets the job done for now.

Hey ,

Apologies for the delay. I was able to reproduce this with your files and have entered UE-43973. You can track the report’s status as the issue is reviewed by our development staff. Please be aware that this issue may not be prioritized or fixed soon.

I’m glad you have a workaround though! Please use that until we have a fix in place.

Hi , thanks for the update!

I will stick to my work around for the mean time, but I’m sure myself and many others would greatly appreciate it if alembic files (and other caching formats) got more love and attention from you guys. With UE being capable of more than just games, filmmakers like me would greatly benefit if these features were fully supported.

As in version 4.17 is now fixed, thanks!