The map data retrieval system, the database which keeps map data retrieval method

摘要

PROBLEM TO BE SOLVED: To retrieve various information in areas by using a designated boundary and dividing a map into a plurality of the closed areas. ;SOLUTION: Boundary data 1001 constituted of a node 1203 and a node 1205 are selected, and boundary data 1002 which appears at first after antiknockwise rotation with the boundary data 1001 as a reference are selected in the left edge node 1205 of the boundary data 1001. Then, boundary data 1003 which appear at first after anticlockwise rotation with the boundary data 1002 as a reference are selected in a left edge node 1207 of the boundary data 1002. The similar processing is repeated until a node 1203 is obtained so that a clockwise polygon 1201 can be extracted.;COPYRIGHT: (C)1999,JPO