Maya blendshapes giving me wrong deformation

Rigging
1

Hey everyone,

I’m having a weird issue I was hoping someone could help me with.

I’m doing corrective blendshapes for a joint based facial rig, and I’m having an issue where the corrective blenshape is deforming the mesh in an unexpected way - basically, it modifies some verts that aren’t supposed to be moving.

I should point out that the “rogue” verts that are modified are always the same ones, in exactly the same way, regardless of the blendshape applied.

I’ve attached some images (one is a GIF) to help understand the issue a little better (note that I used an example that would be very obvious and not an actually usable deformation!).

GIF —> https://drive.google.com/open?id=0B3YQ0nLNYkxZSnUzd1gtdFl0djA

Image outlining problem areas —> https://drive.google.com/open?id=0B3YQ0nLNYkxZTm9qdmhGSTNTa0E

As you can see I highlighted the verts that shouldn’t be moving, but do so when I apply the blendshape. The SAME verts move regardless of the blendshape mesh I apply :frowning:

In terms of the deformation order I’m using, it’s set to “front of chain” - interestingly, the rogue verts are only affected when I use this method - if I use “default”, the issue doesn’t occur, however I can’t use this method since when it is used to correct an already deformed mesh (ie: to correct an open jaw), it deforms it back to the full corrective difference pose.

Can anyone help me out with this? :slight_smile:

2

Hello JHBurton,

Not sure if you found a solution yet but it looks like the issue certainly has something to do with your deformation order. Based on the images you posted everything seems to be pointing in that direction.

Since things seem to be working “better” when you set to deformation order to "default”, I would say set things to default for the time being and manually change your input order. I actually ran into the same thing a few days ago (tried creating a few blendshapes, input order was giving me trouble) and ended up writing a script that helped me pacify some pesky verts. You can download the script on my blog, see if helps.

In a nutshell all this this tool does is use the “reorderDeformers” command but it runs it on every (deformer) input for your mesh. What this does is make sure nothing acts wonky like it sometimes does with Maya’s input window and it also allows you to experiment with different orders quickly until you get something that works for you.

Just to play it safe, another thing you might want to do is check your blendshape’s verts using the Edit Membership Tool or even try making sure your blendshape weights aren’t causing the problem. Hopefully one of these tools will help solve the issue.

-Bryan