Issue No. 10 - October (2010 vol. 32)
Shankar Rao , HRL Laboratories, LLC, Malibu
Roberto Tron , Johns Hopkins University, Baltimore
René Vidal , Johns Hopkins University, Baltimore
Yi Ma , University of Illinois at Urbana-Champaign, Urbana and Microsoft Research Asia, Beijing
In this paper, we study the problem of segmenting tracked feature point trajectories of multiple moving objects in an image sequence. Using the affine camera model, this problem can be cast as the problem of segmenting samples drawn from multiple linear subspaces. In practice, due to limitations of the tracker, occlusions, and the presence of nonrigid objects in the scene, the obtained motion trajectories may contain grossly mistracked features, missing entries, or corrupted entries. In this paper, we develop a robust subspace separation scheme that deals with these practical issues in a unified mathematical framework. Our methods draw strong connections between lossy compression, rank minimization, and sparse representation. We test our methods extensively on the Hopkins155 motion segmentation database and other motion sequences with outliers and missing data. We compare the performance of our methods to state-of-the-art motion segmentation methods based on expectation-maximization and spectral clustering. For data without outliers or missing information, the results of our methods are on par with the state-of-the-art results and, in many cases, exceed them. In addition, our methods give surprisingly good performance in the presence of the three types of pathological trajectories mentioned above. All code and results are publicly available at http://perception.csl.uiuc.edu/coding/motion/.
Motion segmentation, subspace separation, lossy compression, incomplete data, error correction, sparse representation, matrix rank minimization.
R. Vidal, Y. Ma, S. Rao and R. Tron, "Motion Segmentation in the Presence of Outlying, Incomplete, or Corrupted Trajectories," in IEEE Transactions on Pattern Analysis & Machine Intelligence, vol. 32, no. , pp. 1832-1845, 2009.