| 摘要 |
PURPOSE: To make it possible to plot the currently driving road on a display screen even if the map data of the currently driving road are not included in wide area map data by plotting the present traveling road images in superposition on the wide area map on a display screen by using the map information on the currently driving road when the currently driving road are not displayed on the display screen. CONSTITUTION: Whether the currently driving road RDS is displayed on the display screen or not, is judged when the reduced scale level of the map to be displayed is changed to a wide area map level side. If the road is not displayed, the currently driving road image RDS' is generated by using the map information on the currently driving road RDS. The currently driving road image RDS' is superposed on the wide area map and is plotted on the display screen. Consequently, the plotting of the currently driving road RDS in superposition on the wide area map on the display screen is possible even when the map data on the currently driving road RDS are not included in the wide area map data if the reduced scale level of the map to be displayed is changed to the wide area map level side. |
