| 摘要 |
PROBLEM TO BE SOLVED: To decrease the frequency of repetitive processing for reading in and releasing map data even when a road where a vehicle is traveling zigzags nearby the border of a map. SOLUTION: The automobile navigation system 10 reads map data 21 in a memory 14 from a map database 11 and sets a read-in decision area 23 and a release decision area 24 at the periphery of a reference position. When the moving-side border of the read-in decision area 23 moves from the border 26 of the map that the map data 21 represents to the map side of adjacent map data 25, the adjacent map data 25 are read in a memory space 20 in the memory 14 from the map database 11. When the border of the release decision area 24 on the opposite side from the moving-direction side leaves the map that the map data 21 represent while carrying on the movement, the storage area of the map data 21 is released. When a vehicle travels on a road zigzagging nearby the border 26, the repetition of the reading and releasing of map data can be evaded. |
