Abstract

Motion segmentation is an old problem that is receiving re- newed interest because of its role in video analysis. In this paper, we present a Semi-Nonnegative Matrix Factorization (SNMF)method that models dense point tracks in terms of their optical flow, and decomposes sets of point tracks into semantically meaningful motion components. We show that this formulation of SNMF with missing values outperforms the state-of-the-art algorithm of Brox and Malik in terms of accuracy on 10- frame video segments from the Berkeley test set, while being over 100 times faster. We then show how SNMF can be applied to longer videos using sliding windows. The result is competitive in terms of accuracy with Brox and Malik’s algorithm, while still being two orders of magni- tude faster.