Class DouglasPeuckerSimplifier

Simplifies a Geometry using the Douglas-Peucker algorithm.

Inheritance

Object

DouglasPeuckerSimplifier

Inherited Members

Object.Equals(Object)

Object.Equals(Object, Object)

Object.GetHashCode()

Object.GetType()

Object.MemberwiseClone()

Object.ReferenceEquals(Object, Object)

Object.ToString()

Namespace: NetTopologySuite.Simplify

Assembly: NetTopologySuite.dll

Syntax

public class DouglasPeuckerSimplifier

Remarks

Ensures that any polygonal geometries returned are valid. Simple lines are not guaranteed to remain simple after simplification. All geometry types are handled. Empty and point geometries are returned unchanged. Empty geometry components are deleted.

Note that in general D-P does not preserve topology - e.g. polygons can be split, collapse to lines or disappear holes can be created or disappear, and lines can cross. To simplify point while preserving topology use TopologySafeSimplifier. (However, using D-P is significantly faster).

KNOWN BUGS: In some cases the approach used to clean invalid simplified polygons can distort the output geometry severely.

Constructors

DouglasPeuckerSimplifier(Geometry)

Creates a simplifier for a given geometry.

Declaration

public DouglasPeuckerSimplifier(Geometry inputGeom)

Parameters

Type	Name	Description
Geometry	inputGeom	The geometry to simplify.

Properties

DistanceTolerance

The distance tolerance for the simplification.

Declaration

public double DistanceTolerance { get; set; }

Property Value

Type	Description
Double

Remarks

All vertices in the simplified geometry will be within this distance of the original geometry. The tolerance value must be non-negative.

EnsureValidTopology

Controls whether simplified polygons will be "fixed" to have valid topology.

Declaration

public bool EnsureValidTopology { get; set; }

Property Value

Type	Description
Boolean

Remarks

The caller may choose to disable this because:

• valid topology is not required
• fixing topology is a relative expensive operation
• in some pathological cases the topology fixing operation may either fail or run for too long

The default is to fix polygon topology.

Methods

GetResultGeometry()

Gets the simplified geometry.

Declaration

public Geometry GetResultGeometry()

Returns

Type	Description
Geometry	The simplified geometry.

Simplify(Geometry, Double)

Simplifies a geometry using a given tolerance.

Declaration

public static Geometry Simplify(Geometry geom, double distanceTolerance)

Parameters

Type	Name	Description
Geometry	geom	The geometry to simplify.
Double	distanceTolerance	The tolerance to use.

Returns

Type	Description
Geometry	A simplified version of the geometry.

See Also

TopologyPreservingSimplifier