A video surveillance system comprising: an extraction unit which receives video images from each of a plurality of cameras (102, 103) and extracts a motion feature quantity (104, 105), for each of the plurality of cameras, from a plurality of frames constituting the corresponding video image, wherein each motion feature quantity is represented in a coordinate system associated with the corresponding camera; a storage unit for accumulating extraction results from the extraction unit; a virtual viewpoint generation unit for generating a respective virtual viewpoint (306, 307) for each of the plurality of cameras, wherein each virtual viewpoint is based on a virtual installation state information and on the installation information (2033, 2034) of the corresponding camera; a conversion unit including: a three-dimensional position estimation unit for estimating a three-dimensional position of the motion feature quantity extracted by the extraction unit in a real space; and a coordinate conversion unit which is adapted to convert, for each of the extracted motion feature quantities, the extracted motion feature quantity into a respective virtual coordinate system, the virtual coordinate system being associated with the virtual viewpoint corresponding with the camera with which the motion feature quantity corresponds, and the virtual coordinate system being different from each of the coordinate systems associated with the plurality of cameras, wherein the extracted motion feature quantity is converted by using the estimated three-dimensional position; and an analysis unit for analyzing the converted motion feature quantities, characterised in that: the virtual viewpoint generation unit calculates a position of a crossing point between a sight line axis of each of the cameras and the ground level on the basis of the installation information of each of the cameras, and generates each virtual viewpoint such that the crossing point between the sight line axis from each virtual viewpoint and the ground level is matched with the crossing point between the sight line axis of the corresponding camera and the ground level. an extraction unit which receives video images from each of a plurality of cameras (102, 103) and extracts a motion feature quantity (104, 105), for each of the plurality of cameras, from a plurality of frames constituting the corresponding video image, wherein each motion feature quantity is represented in a coordinate system associated with the corresponding camera; a storage unit for accumulating extraction results from the extraction unit; a virtual viewpoint generation unit for generating a respective virtual viewpoint (306, 307) for each of the plurality of cameras, wherein each virtual viewpoint is based on a virtual installation state information and on the installation information (2033, 2034) of the corresponding camera; a conversion unit including: a three-dimensional position estimation unit for estimating a three-dimensional position of the motion feature quantity extracted by the extraction unit in a real space; and a coordinate conversion unit which is adapted to convert, for each of the extracted motion feature quantities, the extracted motion feature quantity into a respective virtual coordinate system, the virtual coordinate system being associated with the virtual viewpoint corresponding with the camera with which the motion feature quantity corresponds, and the virtual coordinate system being different from each of the coordinate systems associated with the plurality of cameras, wherein the extracted motion feature quantity is converted by using the estimated three-dimensional position; and an analysis unit for analyzing the converted motion feature quantities,