<< Brown Games Group
Submitted to ACM Sandbox; SIGGRAPH 2006 Sketch
Dynamo (DYNAmic MOtion capture) Project

Pawel Wrotek, Odest Chadwicke Jenkins, and Morgan McGuire

ACM Sandbox 2006 Paper: [PDF] [Videos]
SIGGRAPH 2006 Sketch: [PDF] [Videos]

Abstract. Dynamo (DYNAmic MOtion capture) is an approach to controlling animated characters in a dynamic virtual world. Leveraging existing methods, characters are simultaneously physically simulated and driven to perform kinematic motion (from mocap or other sources). Continuous simulation allows characters to interact more realistically than methods that alternate between ragdoll simulation and pure motion capture.

The novel contributions of Dynamo are world-space torques for increased stability and a weak root spring for plausible balance. Promoting joint target angles from the traditional parent-bone reference frame to the world-space reference frame allows a character to set and maintain poses robust to dynamic interactions. It also produces physically plausible transitions between motions without explicit blending. These properties are maintained over a wide range of servo gain constants, making Dynamo significantly easier to tune than parent-space control systems. The weak root spring tempers our world-space model to account for external constraints that should break balance. This root spring provides an adjustable parameter that allows characters to fall when significantly unbalanced or struck with extreme force.

We demonstrate Dynamo through in-game simulations of characters walking, running, jumping, and fighting on uneven terrain while experiencing dynamic external forces. We show that an implementation using standard physics (ODE) and graphics (G3D/OpenGL) engines can drive game-like applications with hundreds of rigid bodies and tens of characters, using about 0.002s of CPU time per frame.

Video Results.
All are rendered and simulated at 60 fps or faster and are compressed with the
DivX 6.2 Codec.

ACM Sandbox 2006 Results

dynamo.avi (30M)

SIGGRAPH 2006 Sketch Results

README.TXT (4k) Explanation of videos
Cartwheel.avi (2.5M)
Transitions.avi (2.1M)
GainTuning.avi (1.2M)
Dynamic.avi (22M)
Dynamic-audio.avi (22M, Background Music)