My facial animation solution

After testing a few different facial animation methods in Maya, I settle down with my own method. The ideal is to combining curved based animation and blendshape based animation, utilizing custom python script to get the best of both worlds. 

Blendshape based facial animation is the most accurate and user-friendly way I found so far, but to perform a blendshape deform the machine have to check topology of all the blendshape copies, which preform-wise is very costly. Curved based deform is very light-weight, but user often don't get the optimal result because different curve usually interfere with each other.
As a result, I wrote my own method. First, I copied the face mesh using it as blendshape pipe. Second, I will create curves based on the model's facial structure. Third, the curves were build based on joints, I would use these joints to skin my blendshape mesh. And at last, I will copy and blendshpe the curves and create a blendshape control, so that, I have use my copied curves to blendshape deform the curves on the copied mesh. And pipe all my deform into my original mesh. 

Doing the blendshape nodes this way, I can avoid checking all the topology on the original mesh, the machine only has to check the topology of the curves which is a much lighter calculation. Also, after I created the curves, I can still go back and tweak each curve groups to make sure they can flawlessly blend together. And in the end I can drive the blendshape just like any normal blendshape.

 The whole idea is to use curves to replace blendshape mesh. And by doing blendshape blending on curves, we can accelerate the deformation calculation speed. And here is a snippet of my script that create the blendshape:

As you can see, the script will check if there is already a blendshape node created. If so, it will just add to that blendshape node. And at the last part, I connected the blendshape weight to my circle, so that I can easily control it.