“Spacetime Constraints” by Witkin
Conference:
- SIGGRAPH 1988 More animation videos from SIGGRAPH 1988:
SIGGRAPH Video Review:
Track:
- 16
Title:
- Spacetime Constraints
Director(s):
Company / Institution / Agency:
- Schlumberger Palo Alto Research
Description:
Spacetime Constraints, inspired by Pixar’s Luxo Jr., computes realistic coordinated motion automatically by solving the same physical problem faced by a real creature: muscle control. The goals of motion are specified by constraints using an optimization criterion to choose among the motions that satisfy the constraints.The optimal motion and the corresponding time-varying muscle forces are computed using standard numerical methods. The video shows Luxo performing a variety of jumps. We produce a basic jump just by telling Lux where to start and land. Average muscle power is minimized subject to these constraints, providing a “laziness” criterion. The computed motion exhibits anticipation, squash-and-stretch, and follow-through. These elements emerge out of physical necessity, rather than being explicitly keyframed. Simple changes to the model create interesting variations. For instance, doubling the mass of Luxo’s base produces exaggerated motion. The motion was computed and rendered on Symbolics 3600’s, using in-house software. Most sequences took under 10 minutes to compute.
