Union(Geometry,Geometry) Method

In This Topic

Constructs the set-theoretic union of the input geometries.

Syntax

C#
Visual Basic (Declaration)

Geometry Union( 
   Geometry geometry1,
   Geometry geometry2
)

Overloads Function Union( _
   ByVal geometry1 As Geometry, _
   ByVal geometry2 As Geometry _
) As Geometry

Parameters

geometry1: The first geometry to union with.
geometry2: The second geometry to union with.

Return Value

A geometry representing the union of the input geometries.

Exceptions

Exception	Description
System.ArgumentNullException	Either geometry1 or geometry2 or both are null.
System.NotImplementedException	The method is not implemented for GeometryBag.
System.InvalidOperationException	Incompatible spatial references between the input geometries.
ArcGIS.Core.Geometry.Exceptions.InvalidParameterException	Input geometries do not have the same dimension.
System.NotImplementedException	Spatial reference of geometry1or geometry2is an image coordinate system.

Remarks

If the input geometries are not known-simple, then the operation will be performed on simplified copies of the geometries. There is no need for you to call any simplify method.

If an input geometry is an envelope, then it will be converted to a polygon. If you want the union of two envelopes to be an envelope, then use Envelope.Union.

Example

Union two MapPoints - creates a Multipoint

MapPoint pt1 = MapPointBuilderEx.CreateMapPoint(1.0, 1.0);
MapPoint pt2 = MapPointBuilderEx.CreateMapPoint(2.0, 2.5);

Geometry geometry = GeometryEngine.Instance.Union(pt1, pt2);
Multipoint multipoint = geometry as Multipoint;   // multipoint has point count of 2

Union two Polygons

// union two polygons

List<MapPoint> polyPts = new List<MapPoint>();
polyPts.Add(MapPointBuilderEx.CreateMapPoint(3.0, 2.0));
polyPts.Add(MapPointBuilderEx.CreateMapPoint(3.0, 6.0));
polyPts.Add(MapPointBuilderEx.CreateMapPoint(6.0, 6.0));
polyPts.Add(MapPointBuilderEx.CreateMapPoint(6.0, 2.0));

Polygon poly1 = PolygonBuilderEx.CreatePolygon(polyPts);
bool isSimple = GeometryEngine.Instance.IsSimpleAsFeature(poly1);

Envelope env = EnvelopeBuilderEx.CreateEnvelope(MapPointBuilderEx.CreateMapPoint(4.0, 4.0), MapPointBuilderEx.CreateMapPoint(8, 8));
Polygon poly2 = PolygonBuilderEx.CreatePolygon(env);
isSimple = GeometryEngine.Instance.IsSimpleAsFeature(poly2);

Geometry g = GeometryEngine.Instance.Union(poly1, poly2);
Polygon polyResult = g as Polygon;

Requirements

Target Platforms: Windows 11, Windows 10

ArcGIS Pro version: 3 or higher.

Reference

IGeometryEngine Interface
IGeometryEngine Members
Overload List

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