Patent ID: 6445809
Filing Date: 2002-09-03
Classification: B60R,G01S,G06K,G06T

Abstract:
An environment monitoring system for monitoring a relative relation between one's own vehicle and another surrounding vehicle comprising:image pick-up means for picking up two early and later images which are located at a front, rear or diagonal-rear position from one's own vehicle at two early and later timings and on the basis of the images thus picked-up, detecting white lines of one's own vehicle lane on which one's own vehicle runs; monitoring region setting means for setting a monitoring region in one's own vehicle lane or an adjacent lane on the basis of the white lines thus detected; and optical-flow detecting means for detecting an optical flow generated from another surrounding vehicle within the monitoring region, wherein said optical-flow detecting means comprises: means for reverse-projection converting said early image on the basis of a predetermined optical arrangement of said 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; means for computing a moving distance of one's own vehicle between the two timings on the basis of a time interval between said two timings and speed information of one's own vehicle; means for parallel-shifting the road surface image by the moving distance thus computed; means for projection-converting the road surface image after parallel-shifted to acquire an estimated image of the later image in timing; means for acquiring a differential image between the later image and its estimated image to extract a feature point; and means for searching a corresponding point of the feature point extracted, thereby-detecting the optical flow.