| 摘要 |
PURPOSE:To stably display map data easy to see by setting an extended area obtained by extending a region including the position of a moving body to a prescribed range and omitting to read map data of adjacent maps for display processing into a memory at the time when the moving body exists in the extended area. CONSTITUTION:A drawing device 6 draws a map based on map data from a memory 5 and the direction and the position from a position detector 2. When the moving body exists at a point (a) of map data F, regions A, B, C, E, F, G, I, J, and K are displayed with the region F as the center. In this display state, an extended area F1 indicated by a dot line around the center region F is set. While the moving body exists in the extended area F1, map data is not read into the memory 5; and when the moving body goes out of the extended area F1, map data is read for switching. Then, a next extended area K1 is set. As the result, map data is made easy to see and is stably displayed. |
