A computer implemented method of matching a tagged target group, selected from a plurality of gallery groups in a first camera field of view, with probe groups in a second camera field of view, by determining a group context for the tagged target group, determining, in the second camera field of view, probe contexts for the respective local probe groups in the second camera field of view; matching the group context against the probe contexts to produce respective similarity scores; and identifying based upon the similarity scores, the probe group that matches the tagged target group.