For reference I’m on Blender 3.6.5 and the latest AutoRig Pro (3.68.83)
My workflow for making clothing animations has been the same for a while but now for some reason I’m having trouble with Auto-Rig Pro exporting Alembic animations.
I use a rig made with ARP, to retarget animations from Mixamo and adjust them within the NLA editor.
I select my mesh, then my rig and and export as Alembic (abc.)
The resulting Alembic file is around 4kb (or something very small). Usually they’re at least 1gb.
I reached out to Artell, from ARP and his response was: “I regret to say Auto-Rig Pro does not provide officially support for Alembic. I am not either familiar with this export format. If the Alembic export feature of Blender is not working as expected, please check support forums of Blender such as Blender Artists.”
I’m confused because this workflow worked before. The process works if i use a mixamo rig, so I know it’s ARP causing the issues. Has anyone run into this issue or have any suggestions?
Although I have the ARP Add-on I have not used it much and mainly still use Rigify so not sure how much practical help I can give but I will try with some ideas. I have used Alembic in Blender very successfully in the past in series production about three years back with exporting scenes to and from Maya. But mainly importing Maya rigs and scenes into Blender and effects animations from Blender back into Maya. Yes I often preferred to do 3D effects animation in Blender. I did find the Alembic integration into Blender working well then and never had any problems.
As a test have you tried exporting as an ARP supported format like fbx perhaps then re importing that back into Blender and out again as an Alembic ? The fbx should strip out all the actual rigging and leave only deform bones if I understand it correctly. Or perhaps another test could be to isolate the deform bones in the bone layers then bake the animation onto them directly while unparenting them all. Then parent them to a new root bone as a simple baked FK hierarchy and try exporting that in Alembic along with the skinned character and baked cloth sim.
It’s an annoying fudge but if you are up against a deadline then I would think worth a try. Also a way of begining to trouble shoot what it might be in ARP that is causing the problem.
In my experience of Alembic it is not very good with parenting meshes to rigs. I am thinking of things like eyeballs and teeth. Everything needs to be skinned to be sure it will all export intact. But I am sure you know this already. Just thought it was worth adding in general as perhaps it might be some of the parenting or constriants used in ARP stalling the process.
Another tihng I forgot to mention. Did you try only exporting the deforming meshes to be rendered as Alembic without the rig ? That is in exporting as selected objects only. All the mesh objects will need to be skin bound to the bones and not parented or constrained but often Alembic files will be exported this way stripping out all of the rigging entirely.
This seems to work fine with Rigify rigs in my tests. The cloth sim if it is a baked cache should hopefully follow along.
Sorry for the delayed reply! I really appreciate your suggestions.
TLDR; your first suggestion works!
When trying your first suggestion and exporting as fbx, I realized that my animations were still not being exported. So it must have been my export settings. When I checked, I totally forgot about the dropdown menu for exporting NLA animations vs Actions animations:
once I selected NLA, my animation was successfully exported as fbx. Then I tried your first suggestion and it worked!
I needed to reimport that fbx and then I could finally export as Alembic with the included animation data.
I’m not sure why I cant just export directly as an Alembic when I used to be able to. The Bake Animations dropdown which lets me select NLA is missing from the export dialogue.
