Detection of Different Behavior from The Majority in A Public Space

Abstract

A measurement method was proposed for observing movements of persons in a public space such as a railway station. The method was based on the fact that a person occupied a 3D region and his or her sequential images captured by a security camera formed a wormhole in the spatiotemporal image space. Direction of the majority of those wormholes was estimated as movement direction of the majority by a projection algorithm. After filling the majority wormholes, remaining ones were searched and recognized as different behavior persons. A high-accuracy person extraction algorithm was also developed for preventing wormholes enlargement mainly caused by persons' shadow. An inter-frame difference technique was adopted for realizing the quick updating the background. The method was successfully applied to a security camera video for detecting different behaviors from the majority.

A Method for Deteting Baggage Left in A Crowded Public Space

“…The steady background, however, yielded the less performance against rapid change of environmental illumination, and typically gave us wrong shape of moving person by including shadow at the foot. Our former method, Background Quick Updater (BQU) (10) , removed the shadow by interpreting the pixel having almost the same density in two successive scenes as the background. An inter-frame subtraction technique enabled us to get the accuracy in extracting the moving persons.…”