Walk This Way.(new physics-based animation)(Technology Information)

Physics-based controllers put spring in the step of animated characters

While CG researchers and practitioners have had much success in creating characters that appear "real" on first sight, they have been less successful in attempts to simulate and automate believable human motion. Human motor function is a complex issue in the physical world. Re-creating those complexities in the digital world is a Herculean task. Among the many approaches under development that rise to the challenge, physics-based animation holds significant promise, as it attempts to harness the underlying science of the mechanics of human motion.

Such is what moves the digital crowd in the computer science lab at the University of Toronto, where researcher Petros Faloutsos, along with Michiel van de Panne and Demetri Terzopoulos, have developed a framework of physics-based controllers for enhancing the motor abilities of virtual characters.

"Our physics-based animation technique addresses the difficult, open problem of synthesizing a broad repertoire of realistic human motions by automatically controlling a physically modeled, anthropomorphic graphical character," says Faloutsos. The system is the first to demonstrate a dynamic anthropomorphic character with controlled reactions to disturbances or falls in any direction, as well as the ability to pick itself up off the ground in several ways, among other controlled motions.

Prior work in this area has focused on the design of individual, highly specialized motor controllers tailored to specific actions such as running or certain other athletic actions. In contrast, says Faloutsos, the new technique offers a controller-composition system that combines specialized motor controllers that enable it to tackle the bigger problem of designing significantly broader, more competent control systems for physics-based human characters.

"Our method creates autonomous characters that have an unprecedented range of motor skills, such as balancing in gravity, stepping in a natural, protective manner when balance is disturbed, using the arms to protect the body when falling to the ground, regaining an upright stance in various different ways after a fall, sitting down on a chair and standing back up again, and various other actions," says Faloutsos.

The motion framework comprises families of composable controllers for articulated skeletons whose physical parameters reflect the anthropometric make-up of a fully fleshed adult male.