Issue No.04 - July/August (2010 vol.30)
J.P. Lewis , Weta Digital
Ken-ichi Anjyo , OLM Digital
DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/MCG.2010.41
This paper introduces a simple direct manipulation algorithm for the popular blendshape facial animation approach. As is the case for body animation, direct manipulation of blendshape models is an inverse problem: when a single vertex is moved, the system must infer the movement of other points. The key to solving the inverse problem is the observation that the blendshape sliders are a semantic parameterization -- the corresponding blendshape targets have clear, interpretable functions. Distance in "slider space'' is easily computed and provides the necessary regularization for the inverse problem: The change in semantic position is minimized subject to interpolating the artist's direct manipulations. We give empirical and mathematical demonstrations that a single direct manipulation edit is often the equivalent of multiple slider edits, but the converse is also true, confirming the principle that both editing modes should be supported.
blendshape, facial animation, direct manipulation, inverse kinematics, computer graphics, graphics and multimedia
J.P. Lewis, Ken-ichi Anjyo, "Direct Manipulation Blendshapes", IEEE Computer Graphics and Applications, vol.30, no. 4, pp. 42-50, July/August 2010, doi:10.1109/MCG.2010.41