| 主权项 |
1. A method of creating map data, including search acceleration data arranged to increase the speed at which a route can be planned across an electronic map, the method comprising using at least one processing apparatus to process an electronic map comprising a plurality of navigable segments each representing segments of a navigable route in an area covered by the map, the method comprising:
a) dividing the map into a plurality of hierarchical regions belonging to at least a coarser level and a neighboring finer level such that each navigable segment is categorized into at least one region in each of the coarser and finer levels and wherein any one region of the coarser level contains a plurality of regions of the finer level; b) determining, for a given destination region, the extent of a visibility area, comprising at least the coarser level region containing the destination region, by assessing whether regions close to the coarser level region containing the destination region should be added to the visibility area and adding those regions if the assessment is positive; c) determining, for navigable segments in the visibility area of the destination region, whether a navigable segment is part of a minimum cost route to the destination region, wherein the search performed to make said determination is constrained by the visibility area; d) arranging the search acceleration data to comprise information indicating said determination for the navigable segments; and e) generating the map data. |
