| 摘要 |
A map data acquisition device is integrally mounted to an in-vehicle navigation device. Small scale map data is constantly carried in a database, while large scale, detailed map data is transmitted through communication from an information center serving as a base station. Using the small scale map data, guidance is provided using the main roads. The traveling condition of the vehicle is detected and large scale map data is acquired when judged necessary based on the traveling conditions. For example, when the vehicle deviates from the established route, approaches a construction site indicated by traffic information, or nears the destination, detailed map data is acquired. Therefore, the appropriate detailed map is acquired at an appropriate point to cope with any changes in traveling conditions.
|
