| 摘要 |
PROBLEM TO BE SOLVED: To prevent an unnecessary track data from being stored by limiting the area of the track data to be stored. SOLUTION: It is judged whether at least one node of a link to be stored is within a range RP from the central point PT of a limited area or not (step SQ3). When the node of this link is out of the area, the link data temporarily stored in a RAM is eliminated (step SQ5). The node data related to the eliminated link is eliminated (step SQ7). When the eliminated node is an intersection node, a necessary data correction is performed (step SQ9). |
