Ambiguities in visual tracking of articulated objects using two- and three-dimensional models

James M. Rehg, Daniel D. Morris, Takeo Kanade

Research output: Contribution to journalArticlepeer-review


Three-dimensional (3D) kinematic models are widely-used in video-based figure tracking. We show that these models can suffer from singularities when motion is directed along the viewing axis of a single camera. The single camera case is important because it arises in many interesting applications, such as motion capture from movie footage, video surveillance, and vision-based user-interfaces. We describe a novel two-dimensional scaled prismatic model (SPM)for figure registration. In contrast to 3D kinematic models, the SPM has fewer singularity problems and does not require detailed knowledge of the 3D kinematics. We fully characterize the singularities in the SPM and demonstrate tracking through singularities using synthetic and real examples. We demonstrate the application of our model to motion capture from movies. Fred Astaire is tracked in a clip from the film "Shall We Dance". We also present the use of monocular hand tracking in a 3D user-interface. These results demonstrate the benefits of the SPM in tracking with a single source of video.

Original languageEnglish (US)
Pages (from-to)393-418
Number of pages26
JournalInternational Journal of Robotics Research
Issue number6
StatePublished - Jun 2003
Externally publishedYes


  • Figure tracking
  • Kinematic singularities
  • Motion capture
  • Visual servoing

ASJC Scopus subject areas

  • Software
  • Modeling and Simulation
  • Mechanical Engineering
  • Artificial Intelligence
  • Electrical and Electronic Engineering
  • Applied Mathematics


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