Figure 1: Blendforces merge blendshapes and physically-based animation, allowing for dynamic effects and lip collision handling.
AbstractIn this paper we present a new paradigm for the generation and retargeting of facial animation. Like a vast majority of the approaches that have adressed these topics, our formalism is built on blendshapes. However, where prior works have generally encoded facial geometry using a low dimensional basis of these blendshapes, we propose to encode facial dynamics by looking at blendshapes as a basis of forces rather than a basis of shapes. We develop this idea into a dynamic model that naturally combines the blendshapes paradigm with physics-based techniques for the simulation of deforming meshes. Because it escapes the linear span of the shape basis through time-integration and physics-inspired simulation, this approach has a wider expressive range than previous blendshape-based methods. Its inherent physically-based formulation also enables the simulation of more advanced physical interactions, such as collision responses on lip contacts.
We present the first realtime method for generating facial animations enhanced by physical simulation from realtime performance capture data. Unlike purely data‐based techniques, our method is able to produce physical effects on the fly through the simulation of volumetric skin behaviour, lip contacts and sticky lips. It remains however practical as it does not require any physical/medical data which are complex to acquire and process, and instead relies only on the input of a blendshapes model. We achieve realtime performance on the CPU by introducing an efficient progressive Projective Dynamics solver to efficiently solve the physical integration steps even when confronted to constantly changing constraints. Also key to our realtime performance is a new Taylor approximation and memoization scheme for the computation of the Singular Value Decompositions required for the simulation of volumetric skin. We demonstrate the applicability of our method by animating blendshape characters from a simple webcam feed .
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