Detecting bipedal motion from correlated probabilistic trajectories

  • Authors:

  • Atsuto Maki;Frank Perbet;Björn Stenger;Roberto Cipolla

  • Affiliations:

  • Cambridge Research Laboratory, Toshiba Research Europe, 208 Science Park, Cambridge CB4 0GZ, United Kingdom;Cambridge Research Laboratory, Toshiba Research Europe, 208 Science Park, Cambridge CB4 0GZ, United Kingdom;Cambridge Research Laboratory, Toshiba Research Europe, 208 Science Park, Cambridge CB4 0GZ, United Kingdom;Cambridge Research Laboratory, Toshiba Research Europe, 208 Science Park, Cambridge CB4 0GZ, United Kingdom and Department of Engineering, University of Cambridge, CB2 1PZ, United Kingdom

  • Venue:
  • Pattern Recognition Letters
  • Year:
  • 2013

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Abstract

This paper is about detecting bipedal motion in video sequences by using point trajectories in a framework of classification. Given a number of point trajectories, we find a subset of points which are arising from feet in bipedal motion by analysing their spatio-temporal correlation in a pairwise fashion. To this end, we introduce probabilistic trajectories as our new features which associate each point over a sufficiently long time period in the presence of noise. They are extracted from directed acyclic graphs whose edges represent temporal point correspondences and are weighted with their matching probability in terms of appearance and location. The benefit of the new representation is that it practically tolerates inherent ambiguity for example due to occlusions. We then learn the correlation between the motion of two feet using the probabilistic trajectories in a decision forest classifier. The effectiveness of the algorithm is demonstrated in experiments on image sequences captured with a static camera, and extensions to deal with a moving camera are discussed.