Person Re-Identification in Multi-Camera Networks

Person re-identification consists in matching observations of individuals across disjoint views in a network of surveillance cameras (this task is some times also referred to as multi-camera single person tracking).

This is a non-trivial problem because the appearance of individuals varies greatly through the scenes, due to possibly different acquisition devices and ambient illuminant, changes in viewpoints, illumination conditions, shadows, occlusions, different pose/orientation of the person that has to be searched for, as well as the presence of other similar individuals that populate the scenes.

Re-identification methods can be roughly divided into single-shot and multiple-shot approaches. The former have only one occurrence of the individual to be searched, while the latter integrate information over time using multiple views of the subject by tracking she in the video-stream where she is indicated as suspect by an operator (or by an intelligent module of the surveillance platform). The features to describe the suspect can be biometric (face, gait, height) and/or appearance-based (clothes, pieces of clothes, case). The selection depend on the resolution of the images and the filed of view. In any case, features are used to build a signature of the person. Then they are extracted from the frames of the video streams captured by the surveillance cameras, possibly in restricted regions, e.g. only where people move, to be compared with the signature of the suspect, therefore detecting possible locations of her presence.


Posted in Computer Vision, Projects.