| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an automobile navigation system which can reduce a processing time necessary for searching routes. SOLUTION: Map data in units of rectangular view sheets separated by predetermined longitudes and latitudes are stored in a DVD 2, which are hierarchized in accordance with a detailedness of stored road information. Data related to routes obtained as a result of preliminarily searching under various search conditions routes connecting a boundary node at a boundary of each view sheet to the other view sheet and a superior node present outside the noted view sheet in a predetermined range centering the boundary node (node included in common also in superior hierarchy map data) are stored as extension data accompanying the view sheet in the map data of the view sheet. At a route search time, a route search process part 32 designates one view sheet including a node as a starting point of the route search (e.g. a departure point, a destination or the like), reads in corresponding map data and searches for the route to the superior node.</p> |
