Physically Realistic Morphing

This paper describes an algorithm for automatically adapting existing animated behaviors to new actors with diierent physical characteristics. When simulation is used for animation, this is a diicult problem because a control system that is tuned for one actor will not work on an actor with diierent limb lengths, masses, or moments of inertia. The algorithm presented here adapts the control system to a new actor in two stages. First, the control system parameters are scaled based on the size and moment of inertia of the dynamic models for the new and the old actors. Then a subset of the parameters is ne-tuned using a search process based on simulated annealing. To demonstrate the eeectiveness of this approach, we animate the running motion of a woman and child by modifying the control system for a running man. In addition to adapting a control system for a new model, this approach can also be used to adapt the control system in an on-line fashion to produce a physically realistic metamorphosis from the old model to the new model while the mor-phing model is performing the behavior. We evaluate the results of this approach by comparing the motion of the simulated child and woman with that of actual humans and data published in the literature.