<title>Visual surveillance of human activity</title>

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 IR camera.Unlike many of systems for tracking people, W⁴ makes no use of color cues. Instead, W⁴ employs a combination of shape analysis and tracking to create models of people's appearance so that...