Class CascadedPolygonUnion

Provides an efficient method of unioning a collection of IPolygonal geometries. The geometries are indexed using a spatial index, and unioned recursively in index order. For geometries with a high degree of overlap, this has the effect of reducing the number of vertices early in the process, which increases speed and robustness.

This algorithm is faster and more robust than the simple iterated approach of repeatedly unioning each polygon to a result geometry.
Inheritance
object
CascadedPolygonUnion
Inherited Members
Namespace: NetTopologySuite.Operation.Union
Assembly: NetTopologySuite.dll
Syntax
public class CascadedPolygonUnion

Constructors

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CascadedPolygonUnion(ICollection<Geometry>)

Creates a new instance to union the given collection of Geometrys.

Declaration
public CascadedPolygonUnion(ICollection<Geometry> polys)
Parameters
Type Name Description
ICollection<Geometry> polys

A collection of IPolygonal Geometrys
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CascadedPolygonUnion(ICollection<Geometry>, UnionStrategy)

Creates a new instance to union the given collection of Geometrys.

Declaration
public CascadedPolygonUnion(ICollection<Geometry> polys, UnionStrategy unionStrategy)
Parameters
Type Name Description
ICollection<Geometry> polys

A collection of IPolygonal Geometrys
UnionStrategy unionStrategy

Methods

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Union()

Computes the union of the input geometries.

Declaration
public Geometry Union()
Returns
Type Description
Geometry This method discards the input geometries as they are processed. In many input cases this reduces the memory retained as the operation proceeds. Optimal memory usage is achieved by disposing of the original input collection before calling this method. The union of the input geometries, or null if no input geometries were provided
Exceptions
Type Condition
InvalidOperationException

if this method is called more than once
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Union(ICollection<Geometry>)

Computes the union of a collection of Geometrys.

Declaration
public static Geometry Union(ICollection<Geometry> polys)
Parameters
Type Name Description
ICollection<Geometry> polys

A collection of IPolygonal Geometrys.
Returns
Type Description
Geometry

The union of the polys
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Union(ICollection<Geometry>, UnionStrategy)

Computes the union of a collection of Geometrys.

Declaration
public static Geometry Union(ICollection<Geometry> polys, UnionStrategy unionStrategy)
Parameters
Type Name Description
ICollection<Geometry> polys

A collection of IPolygonal Geometrys.
UnionStrategy unionStrategy

A strategy to perform the unioning.
Returns
Type Description
Geometry

The union of the polys

See Also