| 摘要 |
<p>An information center (2) has an all-road updating data and a main-road updating data. The all-road updating data is a difference of all roads extracted from an all-road map data, and the main-road updating map is a difference of specified roads extracted from the all-road map data. A map display system (1) executes a reverse-updating (S406) to return the map data to a previous state not updated with the main-road updating map data, when its map data has already been updated with the main-road updating data. The map display system (1) then executes updating (S410) of the map data with the all-road updating map data.</p> |
