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Estimation of motion parameters of a rigid body from a monocular image sequence for MPEG-4 applications

: Smolic, A.; Makai, B.; Lin, G.; Sikora, T.

Steinmetz, R.; Wolf, L.C.:
Interactive distributed multimedia systems and telecommunication services. 4th International Workshop IDMS '97 : Darmstadt, Germany, September 10-12, 1997. Proceedings
Berlin: Springer, 1997 (Lecture notes in computer science 1309)
ISBN: 3-540-63519-X
ISSN: 0302-9743
International Workshop on Interactive Distributed Multimedia Services and Telecommunication Services (IDMS) <4, 1997, Darmstadt>
Fraunhofer HHI ()
computer animation; feature extraction; image sequences; kalman filters; motion estimation; prediction theory; recursive estimation; redundancy; parameter estimation; rigid body; monocular image sequence; mpeg-4 applications; snhc face animation; extended kalman filter; prediction/correction loop; temporal redundancies; motion equation linearization

We present a method for the estimation of rigid body motion parameters from a monocular image sequence for MPEG-4 applications, such as SNHC face animation. Based on feature extractions in every frame the motion parameters of a human face are estimated with an extended Kalman filter that performs a prediction and correction loop at every timestep. With this recursive structure of the estimation process the temporal redundancies of the motion are taken into account. The nonlinear motion equation is linearized at every timestep within the extended Kalman filter and therefore the rotation is not restricted to be small and the motion model can be based on the first frame and must not describe the frame to frame motion. Results are presented which demonstrate the accuracy of our estimation method on synthetic data as well as on a real image sequence where we estimated the motion parameters of a human face.