| 摘要 |
PROBLEM TO BE SOLVED: To simply visually confirm a relative height difference of each road on a displayed map by changing a display form of roads based on a reference altitude and absolute altitude information of roads. SOLUTION: The present position is detected by a present position detect means. Map data in the neighborhood of the present position is read from a map data storage means on the basis of the detected present position and stored in a map data temporary storage means. Values above the sea level (Z coordinates) of all nodes and interpolation points of the read map data are compared. A minimum and a maximum values are extracted and set as an Hmin and an Hmax. Then a difference Dh between the Hmax and Hmin is obtained and a display color change width S is obtained. A correspondence table of an altitude and a display color palette No. is formed on the basis of the obtained display color change width S. An altitude Hn of each node and each interpolation point is calculated on the basis of the extracted minimum value Hmin above the sea level. Nodes and interpolation points are linked by a color code of the color palette No. corresponding to the altitude Hn of a starting point of a link to display the link. |
