| 摘要 |
PROBLEM TO BE SOLVED: To allow adequate extraction of a new node or update of the node and accurate estimation of a road shape, by detecting an accurate number of node passings. SOLUTION: A number-of-node-passings calculating portion 1a compares one of absolute coordinates of nodes derived based on presently inputted information from a navigation device 2 with the absolute coordinate of each node stored by the previous time, and determines a reference number of node passings imch0. Based on the number of node passings imch0, inter-node vectors as compared objects are determined among the inter-node vectors stored by the previous time, these inter-node vectors in the determined range are compared with one of the inter-node vectors derived based on presently inputted information from the navigation device 2 to determine the number of node passings imch. |
