Mouth area rigging workflow

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  05 May 2013
Mouth area rigging workflow

I've been thinking about this for a while - how do they deal with this on animated features? It's always such a smooth area around the lips and the mouth can go from a tiny 'o' to a huge smile.. is there any post skin relaxing tricks going on or anything else that's not widely known?

Any thoughts?
  05 May 2013
Very well modeled Blendshapes
And then a layer of joints which rides on top to tweak
Steam Punk Challenge
  05 May 2013
Blendshapes + secondary controls using joints, as doffer said, but volume preserving and skin sliding maintaining curvature can be handled with making those joints pinned to a nurbs curve or plane that follows with the character's geometry so it isn't a linear deformation.

I used to do this often: instead of creating just linear blendshapes you can achieve a really good fake of the full setup above.

Keep in mind, this is not the rig but a way of creating nice non-linear blendshapes, without having to do a lot of modeling by hand (perhaps a little tweaking afterwards):
Assuming you have good edge flow, create a curve via selecting the geometry's edges and using convert to curve. An example for a smile would be creating a curve traveling from the corner of the mouth up along to the cheeks. Tweak it as needed so it more resembles something that will be anatomically correct.

Do this for all areas of the face and mouth, snap and pin 1 joint (end joint only, not a full bone) to each of those curves, do your weight painting as normal. Deform it a little so there is a slight Mona Lisa smile, duplicate the mesh, set it aside, travel up the curve deforming a little bit more so it's a grin, duplicate it, set it aside, deform so it is a small smile, dupe, deform more so it's a full smile etc. to create not 1 or 2 but many inbetween objects. Then delete the joint setup because it is slow, then add all those iterations as you would any blendshape with the inbetween option. Not only does it achieve a curved look, but it simulates skin sliding.
Keep yourself organised as the blendshapes can add up.

Lately I've been using a true skin sliding deformer, such as iDeform (it's free) and incrementally moving joints like before, duplicating meshes that way. I've found purely using the iDeform deformer can produce unnatural results so more modeling is required later, but it's go starting point.

You could argue lots of blendshapes with lots of inbetweens slow down your system, but it is neat and clean since you don't need to have multiple deformation types/methods combined together, such as muscle deformers.

You can do lots of stuff with blenshapes containing multiple inbetweens. For example, you can add a sculpt deformer to the bicep area and incrementally move the sculptor like before simulating bulging with skin sliding, then you can delete the sculpt deformer when done.

Last edited by egglybagelface : 05 May 2013 at 11:03 PM.
  05 May 2013
That's some interesting ideas there, I just keep thinking that a directional smoothing algorithm made available by some plugin would help but I guess careful poking about is what they do... guess I'm doing it right then. Still, a *fast* relaxing deformer would be nice, other apps have had it for a long time and I've seen it in facial rigs as well.

I'll keep that workflow in mind though, thanks!
  05 May 2013
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