Computing the Physical Parameters of Rigid-body Motion from Video


Kiran S. Bhat
Steven M. Seitz
Jovan Popovic
Pradeep K. Khosla


This paper presents an optimization framework for estimating the motion and underlying physical parameters of a rigid body in free flight from video. The algorithm takes a video clip of a tumbling rigid body of known shape and generates a physical simulation of the object observed in the video clip. This solution is found by optimizing the simulation parameters to best match the motion observed in the video sequence. These simulation parameters include initial positions and velocities, environment parameters like gravity direction and parameters of the camera. A global objective function computes the sum squared difference between the silhouette of the object in simulation and the silhouette obtained from video at each frame. Applications include creating interesting rigid body animations, tracking complex rigid body motions in video and estimating camera parameters from video.


Download the paper (ECCV '02): Download the final video (no audio):


Juggling a simple rectangular block:
  • Right is video, left is matched simulation avi (1.3MB)
Matching the motion of a figurine with complex geometry:
  • Matching complex tumbling motion. avi (0.5MB)
Forward prediction:
  • Tracking using simulation parameters . avi (4.8MB)
Gravity estimation:
  • Correcting for camera roll by aligning with gravity direction. avi (10.3MB)