W4: Who? When? Where? What? A real time system for detecting and tracking people

W⁴ is a real time visual surveillance system for detecting and tracking people and monitoring their activities in an outdoor environment. It operates on monocular grayscale video imagery, or on video imagery from an infrared camera. Unlike many of the systems for tracking people, W⁴ makes no use of color cues; instead, W⁴ employs a combination of shape analysis and tracking to locate people and their parts (head, hands, feet, torso) and to create models of people´s appearance so that they can be tracked through interactions such as occlusions. W⁴ is capable of simultaneously tracking multiple people even with occlusion. It runs at 25 Hz for 320×240 resolution images on a dual pentium PC