Class OverlayNGRobust

Performs an overlay operation using OverlayNG, increasing robustness by using a series of increasingly robust (but slower) noding strategies.

The noding strategies used are:

1. A simple fast noder using Floating precision
2. A SnappingNoder using an automatically-determined snap tolerance
3. First snapping each geometry to itself, and then overlaying them wih a SnappingNoder
4. The above two strategies are repeated with increasing snap tolerance, up to a limit
5. Finally a SnapRoundingNoder is used with a automatically-determined scale factor.

If all of the above heuristics fail to compute a valid overlay, the original TopologyException is thrown. In practice this should be extremely unlikely to occur.

This algorithm relies on each overlay operation execution throwing a TopologyException if it is unable to compute the overlay correctly. Generally this occurs because the noding phase does not produce a valid noding. This requires the use of a ValidatingNoder in order to check the results of using a floating noder.

Inheritance

object

OverlayNGRobust

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: NetTopologySuite.Operation.OverlayNG

Assembly: NetTopologySuite.dll

Syntax

public sealed class OverlayNGRobust

Methods

Overlay(Geometry, Geometry, SpatialFunction)

Overlay two geometries, using heuristics to ensure computation completes correctly. In practice the heuristics are observed to be fully correct.

Declaration

public static Geometry Overlay(Geometry geom0, Geometry geom1, SpatialFunction opCode)

Parameters

Type	Name	Description
Geometry	geom0	A geometry
Geometry	geom1	A geometry
SpatialFunction	opCode	The overlay operation code

Returns

Type	Description
Geometry	The overlay result geometry

OverlaySR(Geometry, Geometry, SpatialFunction)

Attempt Overlay using Snap-Rounding with an automatically-determined scale factor.

Declaration

public static Geometry OverlaySR(Geometry geom0, Geometry geom1, SpatialFunction opCode)

Parameters

Type	Name	Description
Geometry	geom0
Geometry	geom1
SpatialFunction	opCode

Returns

Type	Description
Geometry	the computed overlay result, or null if the overlay fails

Union(Geometry)

Computes the unary union of a geometry using robust computation.

Declaration

public static Geometry Union(Geometry geom)

Parameters

Type	Name	Description
Geometry	geom	The geometry to union

Returns

Type	Description
Geometry	The union result

Union(IEnumerable<Geometry>)

Computes the unary union of a collection of geometries using robust computation.

Declaration

public static Geometry Union(IEnumerable<Geometry> geoms)

Parameters

Type	Name	Description
IEnumerable<Geometry>	geoms	An enumeration of geometries to union

Returns

Type	Description
Geometry	The union result

Union(IEnumerable<Geometry>, GeometryFactory)

Computes the unary union of a collection of geometries using robust computation.

Declaration

public static Geometry Union(IEnumerable<Geometry> geoms, GeometryFactory geomFact)

Parameters

Type	Name	Description
IEnumerable<Geometry>	geoms	An enumeration of geometries to union
GeometryFactory	geomFact	The geometry factory to use

Returns

Type	Description
Geometry	The union of the geometries