Detecting Gathering Incident of Video Surveillance Based on Plane Geometry

Gathering is an important incident of video surveillance, possibly reflecting the properties of mass disturbances. However, the incident is more difficult to detect than single-object incidents since it always has multiple detected objects. This paper proposes a plane geometry model to describe the position, trajectory and outline of the detected objects. Gathering incident is checked by a circle in which there are multiple objects. A brief detection algorithm is designed to draw a circle and check whether gathering happens. Finally, several public surveillance videos are tested, and the results indicate the proposed model is efficient, high-detection-rate and robust.