Bearing data for route guidance

摘要

The bearing of a road segment indicates the direction that the segment follows from an end thereof. A primary bearing of a road segment is determined with respect to a significant shape point located along the road segment. The significant shape point is not necessarily the shape point closest to the end point, but is that shape point located within or beyond a predetermined range of distance from the end point. A secondary bearing is determined for some road segments. The secondary bearing indicates the general direction that a road segment follows leading away from an end point. The secondary bearing is determined using a view distance. The view distance is based on attributes of the road segment and represents an estimate of the distance of the driver's field of view as he/she approaches the intersection. Data indicating the primary and secondary bearing can be stored in a geographic database used by a navigation system. A navigation system application uses the primary and secondary bearing data to explicate driving maneuvers. <IMAGE>