Maya - Human IK rig has some hidden offset value, botches blendshapes

Alex_J

edit: I narrowed it down but not sure if there is any non labor intensive fix. I summarize in 2 minute video here : https://youtu.be/uZaaZScRlPA

TL:DW is somehow Daz2Maya Bridge holds mesh at different bind pose that HumanIK. Breaks ability to create new blendshapes.

Hello, I am having a problem with blendshapes setup. I think the problem is somewhere in the humanIK rig though. 

I used the Daz to Maya script which converts the daz rig to HumanIK, as well as sends over existing facial blendshapes. That all works fine. Problem occurs when I create a new blendshape. Whether I add a new blendshape node or add a target to the existing blendshape node, I get much unwanted vertex movement (i.e. the arms are moving even though blendshape target only moved mouth vertices.)

It is not related to the deformation order I think. I've tested that and it all works as expected. i.e., if i set to post deformation the blendshape works, except that it also cancels out my joint deformations. If I set to predeformation, then the problem occurs (but joint deformation works.)

I think it could be something like the daz model has some hidden offset values in the verts because the daz bind pose is different from humanIK? I've checked the CV's values in Channel box and it's all 0,0,0, however. The reason I suspect this is because if I unbind the skin, the model shifts like so:

Note that the arm is offset from the skeleton. So it seems Daz somehow forced the mesh to conform with the skeleton and holds that offset value somewhere? But I dont know how to identify it.

I have attached maya scene here:

https://drive.google.com/file/d/13cLSwqHIySw1FNjFNm-x66QRiKLXP2z9/view?usp=sharing

throttlekitty

I assume that Daz2Maya has rotated the arm joints to the more rigid t-pose that HIK expects before attaching the skeleton to the HIK rig. If you turn off the envelope on the skin cluster you should see the mesh return to what you'd expect to see. So if you need to create any "hardcopy" types of blendshapes, give that a go.

If you weren't aware, Maya's Shape Editor works in pose space; creating a new empty target and sculpting or whatever will give you clean targets that don't have the offset from the skinCluster.

Alex_J

@throttlekitty

you're awesome!

Disabling the envelope did it.

And about your last sentence, that works if I create a new shape by Add Target > edit > sculpt, but if I add a target from selected mesh I still get the unwanted offset. I tried cycling through the different types "Auto, Object, Tangent, etc" but it doesn't make any change. So I'm not sure I understand what is oging on there.

Anyway, I got an easy fix now. Just disbale the envelope when producing the blendshape meshes. Thanks!