System and method for forming a map database with no-outlet and circular segments
View Patent ↗A system and method are provided for forming a map database with attributed data which represents roadways attributed as no-outlet or circular segments. The method includes identifying a segment from a first node to a second node, where the second node is connected to an isolated portion of a road network. The method further includes storing a data attribute into the map database that represents the segment as a road that connects the road network at the first node to the isolated portion of the road network at the second node. The data attribute may represent the segment as a no-outlet segment or a circular segment. A no-outlet segment represents a roadway or portion of a roadway that terminates or returns back to the roadway or portion thereof. A circular segment represents a roadway or portion of a roadway that intersects with a geographic feature, such as a road, and where the roadway or portion thereof leads back to the same geographic feature. The attributed segment may provide directional information to determine the directional nature of the no-outlet or circular segment. The map database with attributed data is particularly useful for route calculation in navigation systems and related applications.
1. A method for forming a map database that contains data that represent roads located in a road network, the method comprising:
identifying a segment from a first node to a second node, where the second node is connected to an isolated portion of the road network through at least one additional segment;
creating an isolated portion data attribute that indicates that said identified segment is connected to said isolated portion of the road network through at least one additional segment; and
storing said isolated portion data attribute into the map database.
2. The method of claim 1 wherein the identified segment is the only segment that connects the road network with the isolated portion of the road network.
3. The method of claim 2 wherein the identified segment is attributed as a no-outlet segment from the first node to the second node.
4. The method of claim 1 wherein the identified segment is one segment of two or more segments that only connect the road network at a same road with the isolated portion of the road network.
5. The method of claim 4 wherein the identified segment is attributed as a circular segment from the first node to the second node.
6. The method of claim 4 wherein the road has the same name at each segment of the road where the two or more segments connect.
7. The method of claim 1 wherein the isolated portion of the road network is a dead-end that is represented only by a node.
8. The method of claim 1 wherein the isolated portion of the road network is represented by a collapsed node.
9. The method of claim 1 wherein the isolated portion of the road network is represented by a plurality of segments interconnected by a plurality of nodes.
10. The method of claim 9 wherein the attributed data represents the plurality of road segments and the plurality of nodes as the isolated portion of the road network.
11. The method of claim 1 further comprising:
storing the map database on a computer readable medium.
12. A map database formed according to the process of claim 1 .