Amobile System Combining Laser Scanners and Cameras for Urban Spatial Objects Extraction

This paper describes a vehicle-borne mapping system which combines laser scanners, cameras and navigation unit for urban spatial object extraction especially the traffic signs/signals. Considering the high cost of searching candidates of urban spatial objects in images, candidates are searched in laser points. As laser scanners and cameras are calibrated into a common reference frame, laser points can be projected onto images to perform candidate verification. The combination of laser scanners and cameras can reduce the search space in images. Moreover laser points provide precise 3d position for the candidate.