com.vividsolutions.jts.operation.valid

Class ConsistentAreaTester

java.lang.Object

com.vividsolutions.jts.operation.valid.ConsistentAreaTester

public class ConsistentAreaTester
extends Object

Checks that a GeometryGraph representing an area (a Polygon or MultiPolygon ) has consistent semantics for area geometries. This check is required for any reasonable polygonal model (including the OGC-SFS model, as well as models which allow ring self-intersection at single points)

Checks include:

• test for rings which properly intersect (but not for ring self-intersection, or intersections at vertices)
• test for consistent labelling at all node points (this detects vertex intersections with invalid topology, i.e. where the exterior side of an edge lies in the interior of the area)
• test for duplicate rings

If an inconsistency is found the location of the problem is recorded and is available to the caller.

Version:

1.7

Constructor Summary

Constructors

Constructor and Description
ConsistentAreaTester(GeometryGraph geomGraph) Creates a new tester for consistent areas.

Method Summary

Modifier and Type	Method and Description
Coordinate	getInvalidPoint()
boolean	hasDuplicateRings() Checks for two duplicate rings in an area.
boolean	isNodeConsistentArea() Check all nodes to see if their labels are consistent with area topology.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ConsistentAreaTester

public ConsistentAreaTester(GeometryGraph geomGraph)

Creates a new tester for consistent areas.

Parameters:

geomGraph - the topology graph of the area geometry

Method Detail

getInvalidPoint

public Coordinate getInvalidPoint()

Returns:

the intersection point, or null if none was found

isNodeConsistentArea

public boolean isNodeConsistentArea()

Check all nodes to see if their labels are consistent with area topology.

Returns:

true if this area has a consistent node labelling

hasDuplicateRings

public boolean hasDuplicateRings()

Checks for two duplicate rings in an area. Duplicate rings are rings that are topologically equal (that is, which have the same sequence of points up to point order). If the area is topologically consistent (determined by calling the isNodeConsistentArea, duplicate rings can be found by checking for EdgeBundles which contain more than one EdgeEnd. (This is because topologically consistent areas cannot have two rings sharing the same line segment, unless the rings are equal). The start point of one of the equal rings will be placed in invalidPoint.

Returns:

true if this area Geometry is topologically consistent but has two duplicate rings