Person identification using shadow analysis

We introduce a novel person identification method for a surveillance system of much wider area than conventional systems using CCTV cameras. In the proposed system, we install cameras to rooftops of buildings or a low altitude airship, and identify people by gait features extracted from shadows, which are projected on the ground by the sun in the daytime or lights in the evening. Since conventional systems extract gait features from actual body area, the correct classification ratio is reduced due to the lack of information of body area, in case that images are captured by overhead cameras. On the other hand, the proposed system enables to identify people by gait features which are extracted from shadows projected on the ground, even if images are captured by overhead cameras. In the proposed system, shadow areas projected on the ground are extracted automatically from captured images, and then analyze dynamics of shadow areas by the spherical harmonics. Experiments of person identification using actual outside images revealed that the proposed method showed the best performance than conventional methods, and the results indicate the feasibility of person identification based on shadow analysis.