MODEL-BASED TRACKING OF COMPLEX INNERCITY ROAD INTERSECTIONS

Vision-based automatic driving along innercity roads and across comple x innercity intersections requires to detect and track road markings a nd lane boundaries in order to determine the position and orientation of the vehicle relative to the ground. The complexity of intersection scenes and the disturbances in the detected contours enforce the use o f model-based state estimation techniques. We recorded monocular image sequences of complex innercity road intersections from a moving small experimental truck in order to track intersection models using a Kalm an filter. A scalar distance measure for the distance between image co ntour points and model edge segments turned out to be advantageous for the estimation process. This scalar measure is based on the simultane ous exploitation of edge element location and direction,;thus using mo re information about the image gray value variation than previously wh en only the perpendicular distance between the edge element and the mo del segment was taken into account. We report about the theoretical fo undation of this approach, its implementation and experimental results from several intersection sequences,;as well as detailed comparisons with a previous, less sophisticated approach. These examples demonstra te the kind of problems which are likely to occur more frequently at i ntersection scenes than at those road scenes encountered while followi ng a, more or less straight, uninterrupted highway lane with clearly m arked boundaries. (C) 1998 Elsevier Science Ltd. All rights reserved.