Integrating Social Grouping for Multitarget Tracking Across Cameras in a CRF Model

Tracking multiple targets across nonoverlapping cameras aims at estimating the trajectories of all targets, and maintaining their identity labels consistent while they move from one camera to another. Matching targets from different cameras can be very challenging, as there might be significant appearance variation and the blind area between cameras makes the target’s motion less predictable. Unlike most of the existing methods that only focus on modeling the appearance and spatiotemporal cues for inter-camera tracking, this paper presents a novel online learning approach that considers integrating high-level contextual information into the tracking system. The tracking problem is formulated using an online learned conditional random field (CRF) model that minimizes a global energy cost. Besides low-level information, social grouping behavior is explored in order to maintain targets’ identities as they move across cameras. In the proposed method, pairwise grouping behavior of targets is first learned within each camera. During inter-camera tracking, track associations that maintain single camera grouping consistencies are preferred. In addition, we introduce an iterative algorithm to find a good solution for the CRF model. Comparison experiments on several challenging real-world multicamera video sequences show that the proposed method is effective and outperforms the state-of-the-art approaches.