| 摘要 |
PURPOSE:To speed up search processing by storing road network data such as intersection data and road data in hierarchic structure and making a search from a low layer to a high layer in order. CONSTITUTION:For example, a start point and a destination are indicated by an intersection number I in a block 1 in a layer 1 and an intersection number III in a block 6. Intersection numbers in the high layer are found, a route up to intersection numbers III and IV is searched for, and the high layer is entered. The intersection number III in the block 6 moves up to the high layer as it is since there is an intersection number VIII in the layer 1 of the high layer. In the layer 1 of the high layer, the route from the intersection number I or II to the intersection number VIII is searched for in the layer 1 of the high layer in combination with information searched for in the layer 1. Consequently, the calculation time for the route search can be shortened. |
