Abstract: In an environment monitoring system using an optical flow, a monitoring region is set in one's own vehicle lane or an adjacent lane on the basis of the white lines. In this case, an early image is divided into a plurality of small regions. An edge is extracted which is an candidate of each the white lines for each the small regions using a virtual FOE for each the small regions acquired previously of the early image. A white line is determined is determined on the basis of the edge extracted. Finally, white line segments are extended for each small region determined to acquire a coordinate of a crossing point thereof and that of the virtual FOE is stored for each the small regions. The virtual FOE is used to extract the edge for each of the small regions of an image newly picked-up in order to detect the optical flow.

Abstract: In an environment monitoring system using an optical flow, an optical-flow detecting device detects the optical flow in the steps of reverse-projection converting the early image of two early and later images picked up by an image picked up, on the basis of a predetermined optical arrangement of the image pick-up means onto an x-z plane in parallel to a road surface in a real space to acquire a road surface image; computing a moving distance of one's own vehicle in two timings on the basis of a time interval between two timings and speed information of one's own vehicle; parallel-shifting the road surface image by the moving distance thus computed; projection-converting the road surface image after parallel-shifted to acquire an estimated image of the later image in timing; acquiring a differential image between the later image and its estimated image to extract a feature point; and searching a corresponding point of the feature point extracted.