To obtain an omnidirectional property by which several cameras have a common effective optical center by arranging the several cameras so that different reflection surfaces of a polyhedron such as a pyramid may be viewed by the several cameras, respectively.

Cameras 52 to 58 are provided with a common virtual optical center in a pyramid and the pyramid 40 is provided with reflection surfaces 42 to 48. The reflection surfaces 42 to 48 form an angle of 45° with a plane passing through an apex of the pyramid 40 and parallel with a base surface 50. The cameras 52 to 58 are respectively related to the reflection surfaces 42 to 48 of the pyramid. Then, reflection from the reflection surface 48 (42, 44 and 46) is observed so that an object may be viewed by the camera 52 (54, 56 and 58) in a direction shown by an arrow 60 (62, 64 and 66). Thus, a 360° visual field surrounding the pyramid 40 is generated by combining observed reflected images of the cameras 52 to 58 having the 90° visual field from the reflection surfaces 42 to 48 of the pyramid 40. The optical centers of the cameras 52 to 58 are arranged on a line passing the apex 70 and perpendicular to the base line of the reflection surfaces 42 to 48.