Controlling deformable material with dynamic morph targets.

ABSTRACTWe present a method to control the behavior of elastic, deformable material in a dynamic simulation. We introduce dynamic morph targets, the equivalent in dynamic simulation to the geometric morph targets in (quasi-static) modeling. Dynamic morph targets define the pose-dependent physical state of soft objects, including surface deformation and elastic and inertial properties. Given these morph targets, our algorithm then derives a dynamic model that can be simulated in time-pose-space, interpolating the dynamic morph targets at the input poses. Our method easily integrates with current modeling and animation pipelines: at different poses, an artist simply provides a set of dynamic morph targets. Whether these input states are physically plausible is completely up to the artist. The resulting deformable models expose fully dynamic, pose-dependent behavior, driven by the artist-provided morph targets, complete with inertial effects. Our deformable models are computationally efficient at runtime through modal reduction and pose-space polynomial interpolation. These models can therefore be plugged into existing dynamic simulation engines, either forming interactive, deformable content in real-time games or providing secondary dynamic effects for kinematically-driven characters in feature animation films. Finally, our method also facilitates certain time-consuming rigging procedures, by providing a physically based approach to resolve co-articulation deficiencies in traditional skinning methods, such as in shoulder regions, fully automatically.