Hi guys, I’m experiencing a big problem.
My goal is to export metahuman head skeletal mesh to external DCC (houdini) and sculpt it and then import it back to unreal engine.
But I stuck at the first step.
The problem is 
Even I just do a plain and clean export and then do NO edit with any DCC and then import back. And then the new imported “same” skeletal mesh loses all the animation imformation, and thus cannot use the old head’s metahuman standard control rig and animation and live link.
Step to Produce
Step1.
Just export a standard metahuman character’s head.
Step2.
Don’t do anything, no zbrush sculpt, no 3DSMAX editpoly, no maya Mesh edit.
>>Just Re-import<< it back like this
Step3.
Then it fails. It indeed has those morph target channels.
But all the animation won’t work, all the control rigs won’t work.
You see, the default ARKIT animation has no effect on this
I also use this link’s tutorial to create a duplicated metahuman head’s control rig and assign it to the re-imported mesh (Their skeleton is same)
But it does not work either.
What am I missing?
My own reseach so far:
1.
I found that the default export/import operations is leaking: It is not symmetry.
The original standard metahuman’s character head skeletal asset is about 120~350 MB of size and 35,184 verts, but the re-imported skeletal mesh asset only has 20 MB size and 34,841 verts. Their bones and morph target’s number is the same.
I really don’t know why the animation after re-import is losing…
Isn’t metahuman’s head animation is driven by head skeleton directly?
And that’s where my second confusion at: If the metahuman’s facial animation is driven by skeleton, why do we need all those morph targets? Are they of somewhat redundency?
And how do I achieve the pipeline at last…I tried my best to modify the mesh’s shape and maintained its topology (not a single verts added), but unfortunaly even meshes without edit cannot re-use exisitng assets just after a re-import.