com.vividsolutions.jts.operation.union

Class UnaryUnionOp

java.lang.Object

com.vividsolutions.jts.operation.union.UnaryUnionOp

public class UnaryUnionOp
extends Object

Unions a collection of Geometry or a single Geometry (which may be a collection) together. By using this special-purpose operation over a collection of geometries it is possible to take advantage of various optimizations to improve performance. Heterogeneous GeometryCollections are fully supported.

The result obeys the following contract:

• Unioning a set of overlapping Polygons has the effect of merging the areas (i.e. the same effect as iteratively unioning all individual polygons together).
• Unioning a set of LineStrings has the effect of noding and dissolving the input linework. In this context "fully noded" means that there will be an endpoint or node in the result for every endpoint or line segment crossing in the input. "Dissolved" means that any duplicate (i.e. coincident) line segments or portions of line segments will be reduced to a single line segment in the result. This is consistent with the semantics of the Geometry.union(Geometry) operation. If merged linework is required, the LineMerger class can be used.
• Unioning a set of Points has the effect of merging all identical points (producing a set with no duplicates).

UnaryUnion always operates on the individual components of MultiGeometries. So it is possible to use it to "clean" invalid self-intersecting MultiPolygons (although the polygon components must all still be individually valid.)

Author:

mbdavis

Constructor Summary

Constructors

Constructor and Description
UnaryUnionOp(Collection geoms)
UnaryUnionOp(Collection geoms, GeometryFactory geomFact)
UnaryUnionOp(Geometry geom)

Method Summary

Methods

Modifier and Type	Method and Description
Geometry	union() Gets the union of the input geometries.
static Geometry	union(Collection geoms)
static Geometry	union(Collection geoms, GeometryFactory geomFact)
static Geometry	union(Geometry geom)

Methods inherited from class java.lang.Object

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

Constructor Detail

UnaryUnionOp

public UnaryUnionOp(Collection geoms,
            GeometryFactory geomFact)

UnaryUnionOp

public UnaryUnionOp(Collection geoms)

UnaryUnionOp

public UnaryUnionOp(Geometry geom)

Method Detail

union

public static Geometry union(Collection geoms)

union

public static Geometry union(Collection geoms,
             GeometryFactory geomFact)

union

public static Geometry union(Geometry geom)

union

public Geometry union()

Gets the union of the input geometries. If no input geometries were provided, a POINT EMPTY is returned.

Returns:

a Geometry containing the union or an empty GEOMETRYCOLLECTION if no geometries were provided in the input