Simple Steps for Simply Stepping

We introduce a general method for animating controlled stepping motion for use in combining motion capture sequences. Our stepping algorithm is characterized by two simple models which idealize the movement of the stepping foot and the projected center of mass based on observations from a database of step motions. We draw a parallel between stepping and point-to-point reaching to motivate our foot model and employ an inverted pendulum model common in robotics for the center of mass. Our system computes path and speed profiles from each model and then adapts an interpolation to follow the synthesized trajectories in the final motion. We show that our animations can be enriched through the use of step examples, but also that we can synthesize stepping to create transitions between existing segments without the need for a motion example. We demonstrate that our system can generate precise, realistic stepping for a number of scenarios.