Interactive Motion Editing


Recently, capturing live motion has become one of the most promising technologies in character animation because the naturalness of live performers can be easily duplicated in a virtual world. Much of the recent research in computer animation has been devoted to developing various kinds of editing tools to produce convincing animation from canned motion clips. Although recent progress in motion capture technology has made it relatively easy to obtain high-quality motion, reusing the data is hard because the motion was acquired for a specific performer, within a specific environment, and in a specific context.

Modifying and varying existing motions is often formulated as an optimization problem in which desired features of the target motion -- for example, foothold and handhold positions when climbing the ladder -- are identified as constraints. Previous approaches cast this problem as a very large non-linear optimization that is cumbersome to handle. Instead, we decoupled the problem into manageable subproblems, each of which can be solved very efficiently using hierarchical displacement mapping and a fast, specialized inverse kinematics solver. The inverse kinematics solver allow the character's pose at each frame to be adjusted to meet given constraints. Hierarchical displacement mapping allows the resulting poses to be interpolated smoothly and accurately.  This technique can be used for interactive motion editing and adapting motion to compensate for geometric variations in characters and environments.

The left figure shows the original motion and the right figure shows its adaptation to a new character that has a shorter body, shorter arms, and longer legs

Character morphing: The size of the character changes over time

The upper figure show the original motion and the lower figure shows its adaptation to uneven terrain.






[Last modified : Feb 11, 2003]