Occlusion-aware multiple camera reconfiguration

This paper deals with the problem of camera networks reconfiguration. In particular, the case of Pan-Tilt-Zoom (PTZ) cameras is considered, and a method is proposed in order to automatically change the pan, tilt and zoom parameters in order to maximize the coverage of relevant portions of the observed environment. Here, the "relevant portions" are defined in terms of motion activity maps, measuring the passage of moving objects over a map of the monitored scene, however the method can be applied to arbitrary maps. Moreover, occlusions are explicitly handled, so that the map is different for each camera, depending on which portions of the scene are visible from a given point of view. The proposed technique works by approximating the observed zones with ellipses and finds a locally optimal solution by using the Expectation Maximization algorithm. In order to avoid unfeasible solutions (ellipses that cannot be obtained by any PTZ configuration) the computation is performed in a proper space where the geometric constraints due to the camera positions become null.