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International Journal of Computer Vision

, Volume 38, Issue 2, pp 99–127 | Cite as

Optical Flow Constraints on Deformable Models with Applications to Face Tracking

  • Douglas DeCarlo
  • Dimitris Metaxas
Article

Abstract

Optical flow provides a constraint on the motion of a deformable model. We derive and solve a dynamic system incorporating flow as a hard constraint, producing a model-based least-squares optical flow solution. Our solution also ensures the constraint remains satisfied when combined with edge information, which helps combat tracking error accumulation. Constraint enforcement can be relaxed using a Kalman filter, which permits controlled constraint violations based on the noise present in the optical flow information, and enables optical flow and edge information to be combined more robustly and efficiently. We apply this framework to the estimation of face shape and motion using a 3D deformable face model. This model uses a small number of parameters to describe a rich variety of face shapes and facial expressions. We present experiments in extracting the shape and motion of a face from image sequences which validate the accuracy of the method. They also demonstrate that our treatment of optical flow as a hard constraint, as well as our use of a Kalman filter to reconcile these constraints with the uncertainty in the optical flow, are vital for improving the performance of our system.

Keywords

Kalman Filter Tracking Error Optical Flow Constraint Violation Hard Constraint 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Kluwer Academic Publishers 2000

Authors and Affiliations

  • Douglas DeCarlo
    • 1
  • Dimitris Metaxas
    • 2
  1. 1.Department of Computer Science, and Center for Cognitive ScienceRutgers UniversityPiscatawayUSA
  2. 2.Department of Computer and Information ScienceUniversity of PennsylvaniaPhiladelphiaUSA

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