Biomechanically accurate finite element models of facial musculature offer a superior accuracy in reproducing facial expressions, the ability to adapt the simulation model to a particular subject as well as a compact and biophysically meaningful parameterization of expressions in terms of the muscle activations and bone motion that give rise to them. We employ such a finite element simulation model to determine the muscle activations and kinematic configuration of the rigid bones associated with an expression from a sparse sampling of the deformation of the face surface over time, acquired using a motion capture system. We use a hyperelastic, transversely isotropic constitutive model to simulate passive flesh and 32 dominant muscles of the face. Our simulation model, consisting of 840K tetrahedral elements, was created through non-rigid registration of a muscle geometry template derived from the Visible Human dataset to MRI volumetric data acquired from the motion capture subject.

@InProceedings{SF05,
  author       = "Sifakis, Eftychios and Fedkiw, Ronald",
  title        = "Facial Muscle Activations from Motion Capture",
  booktitle    = "Computer Vision and Pattern Recognition Conference (CVPR)",
  year         = "2005",
  url          = "http://graphics.cs.wisc.edu/Papers/2005/SF05"
}