Archive for February 9th, 2012
Oh joy, it’s time to rig faces in Maya.
It’s not something I look forward to, and that probably has something to do with the fact that the first time I went through these motions, I took a very literal path from point A to point B, in which I used wire tools, and cluster deformers to achieve facial movement.
But as with most subjects on this blog, I’m not satisfied with that method, as it’s tedious and time consuming, so this time I’m going to use Blend shapes, which can be equally torturous but for which I’m introducing an intermediary step linking wire deformers and Blend shapes using lattice deformers and cluster deformers to get there.
Here’s my assumed start position:
We’re going to start with the mouth and create a wire deformer for it, so I select the appropriate poly-edges around the mouth, and use the Modify>Convert>Polygon Edges to Curve to create the controlling wire.
Go ahead and create a new Wire Deformer from the Create Deformers menu using the the original curve and the object with the face you intend to animate. Now I know I said that we’re using other deformers as an intermediate to get to the Blend Shape deformers, but we’re going to actually create the Blend shape node now, using the two existing curves as the basis.
This is good, but the curve has so many control points that adjusting them for each shape will be almost as much of a pain as if we were adjusting verts by hand on the model. We could weed them out, but the fit would be sacrificed, not to mention that we’d have to delete the same CV’s on both curves in the same order to keep the Blend shape working as intended.
Rather than get bogged down in all that, create a lattice deformer around the top and bottom CV’s respectively. For demonstration purposes, I’ve just done the top set here for clarity.
The advantage of lattice deformers is that they take high density curves and polys and smooth the deformation over a larger area. We can control those now by manipulating clusters we can attach to the lattice points as seen in the second of two images above.
Let’s say this is the expression we want for our next blend shape. Duplicate the secondary curve in its’ deformed shape and add that as your next blend shape target. A new target with slider shows up in the Blend Shape window. Sliding it produces a duplicate of the exact same deformation that you got a moment ago manipulating the cluster. Another benefit of the cluster deformer, is the ability to reset its’ position back to ‘zero’, over and over again, repeatedly creating new Blend Shape targets, and so on and so forth.
Lastly, it should be noted that Blend Shape deformer nodes, as long as they are defined as “Local” when created, are free to be attached directly under the character or skeleton’s node without having to account for double transformations, a tedious step involved in most other types of animation control rigs. Just remember to parent both the wire and the baseWire shapes to the appropriate part of the anatomy and/or rig, and the blend shape should still work as intended.