Minimum description length region tracking with level sets

This paper addresses the problem of tracking an arbitrary region in a sequence of images, given a pre-computed velocity field. Such a problem is of importance in applications ranging from video surveillance to video database search. The algorithm presented here formulates tracking as an estimation problem. We propose, as our estimation criterion, a precise description length measure that quantifies tracking performance. In this context, tracking is naturally formulated as minimum description length estimation. The solution to this estimation problem is given by particular evolution equations for the region boundary. The implicit representation of the region boundary by the zero level set of a smooth function yields an equivalent set of partial differential equations and the added benefit of topology independence; regions may split (e.g., for divergent velocity fields) or merge (e.g., for convergent velocity fields) during tracking, clearly a desirable feature in real-world applications. We illustrate the performance of the proposed algorithm on a number of real images with natural motion.