Persistent people tracking and face capture using a PTZ camera

Pan–tilt–zoom (PTZ) camera is a powerful tool in far-field scenarios. However, most of the current PTZ surveillance systems require manual intervention to move the camera to the desired position. In this paper, we address the problem of persistent people tracking and face capture in uncontrolled scenarios using a single PTZ camera, which could prove most helpful in forensic applications. The system first detects and tracks pedestrians in zoomed-out mode. Then, according to a scheduler, the system selects a person to zoom in. In the zoomed-in mode, we detect a set of face images and solve the face–face association and face–person association problems. The system then zooms back out where tracking is continued as people re-appear in the view. The person–person association module associates the people on the schedule list with the people in the current view. The detected faces are associated with the corresponding people and trajectories. Due to the dynamic nature of our problem, e.g. the field of view of the camera changes because of the pan/tilt/zoom movement of the camera, all of the processes including receiving images from the camera and processing must be done in real time. To the best of our knowledge, the proposed method is the first to address the association of face images to people and trajectories using a single PTZ camera. Extensive experiments in challenging indoor and outdoor uncontrolled conditions demonstrate the effectiveness of the proposed system.