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UBC Theses and Dissertations

Directable physics-based character animation Kim, Nam Hee


Animated motions should be simple to direct while also being plausible. The work presented in this thesis develops a trajectory optimization system that takes as input a sequence of crudely-specified keyframes as motion sketches and produces a physically simulated, as-plausible-as-possible motion as output. We propose a novel control parameterization scheme for trajectory optimization, compactly incorporating keyframe timing, internal actions, and external assistive force modulations as auxiliary variables to realize desired motion sketches. Our method allows for emergent behaviours between keyframes, does not require advance knowledge of contacts or exact motion timing, supports the creation of physically-impossible motions, and allows for near-interactive motion creation. The use of a shooting method allows for the use of any black-box simulator. We present results for a variety of 2D and 3D motions, motion sketches that have sparse and dense keyframes, and both physically-feasible and physically-infeasible motions. We evaluate our control parameterization scheme against other recent methods that incorporate external assistive forces. Supplementary materials available at: http://hdl.handle.net/2429/78212

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