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ArcGIS Runtime SDK for .NET

Perform spatial operations

This code sample is available for these platforms:
View Sample on GitHub

Find the union, intersection, or difference of two geometries.


Use case

The different spatial operations (union, difference, symmetric difference, and intersection) can be used for a variety of spatial analyses. For example, government authorities may use the intersect operation to determine whether a proposed road cuts through a restricted piece of land such as a nature reserve or a private property. When these operations are chained together, they become even more powerful. An analysis of food deserts within an urban area might begin by union-ing service areas of grocery stores, farmer's markets, and food co-ops. Taking the difference between this single geometry of all services areas and that of a polygon delineating a neighborhood would reveal the areas within that neighborhood where access to healthy, whole foods may not exist.

How to use the sample

The sample provides an option to select a spatial operation. When an operation is selected, the resulting geometry is shown in red. The 'reset operation' button undoes the action and allow selecting a different operation.

How it works

  1. Create a GraphicsOverlay and add it to the MapView.
  2. Define a PointCollection of each Geometry.
  3. Add the overlapping polygons to the graphics overlay.
  4. Perform spatial relationships between the polygons by using the appropriate operation:
    • GeometryEngine.Union(geometry1, geometry2) - This method returns the two geometries united together as one geometry.
    • GeometryEngine.Difference(geometry1, geometry2) - This method returns any part of Geometry2 that does not intersect Geometry1.
    • GeometryEngine.SymmetricDifference(geometry1, geometry2) - This method returns any part of Geometry1 or Geometry2 which do not intersect.
    • GeometryEngine.Intersection(geometry1, geometry2) - This method returns the intersection of Geometry1 and Geometry2.
  5. Use the geometry that is returned from the method call to create a new Graphic and add it to the graphics overlay for it to be displayed.

Relevant API

  • Geometry
  • GeometryEngine
  • GeometryEngine.Difference
  • GeometryEngine.Intersection
  • GeometryEngine.SymmetricDifference
  • GeometryEngine.Union
  • Graphic
  • GraphicsOverlay


analysis, combine, difference, geometry, intersection, merge, polygon, union

Sample Code

<?xml version="1.0" encoding="utf-8" ?>
        <esriUI:MapView x:Name="MyMapView" />
                <Label Text="Select a spatial operation:">
                        <OnPlatform x:TypeArguments="Color">
                            <On Platform="Android" Value="DarkGray" />
                        <OnPlatform x:TypeArguments="Color">
                            <On Platform="Android" Value="DarkGray" />
                    Text="Reset operation"
                    WidthRequest="253" />
// Copyright 2018 Esri.
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.
// You may obtain a copy of the License at:
// Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific
// language governing permissions and limitations under the License.

using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.UI;
using System.Collections.Generic;
using Xamarin.Forms;
using Colors = System.Drawing.Color;

namespace ArcGISRuntimeXamarin.Samples.SpatialOperations
    [ArcGISRuntime.Samples.Shared.Attributes.Sample("Spatial operations",
        "Demonstrates how to use the GeometryEngine to perform geometry operations between overlapping polygons in a GraphicsOverlay.",
        "The sample provides a drop down on the top, where you can select a geometry operation. When you choose a geometry operation, the application performs this operation between the overlapping polygons and applies the result to the geometries.")]
    public partial class SpatialOperations : ContentPage
        // GraphicsOverlay to hold the polygon graphics.
        private GraphicsOverlay _polygonsOverlay;

        // Polygon graphics to run spatial operations on.
        private Graphic _graphicOne;
        private Graphic _graphicTwo;

        // Graphic to display the spatial operation result polygon.
        private Graphic _resultGraphic;

        public SpatialOperations()

            // Create the map, set the initial extent, and add the polygon graphics.

        private void Initialize()
            // Create the map with a gray canvas basemap and an initial location centered on London, UK.
            Map myMap = new Map(BasemapType.LightGrayCanvas, 51.5017, -0.12714, 15);

            // Add the map to the map view.
            MyMapView.Map = myMap;

            // Create and add two overlapping polygon graphics to operate on.

            // Fill the combo box with some spatial operations to run on the polygon graphics.
            SpatialOperationComboBox.Items.Add("Symmetric difference");

        // Handle the spatial operation selection by performing the operation and showing the result polygon.
        private void SpatialOperationComboBox_SelectedIndexChanged(object sender, System.EventArgs e)
            // If an operation hasn't been selected, return.
            if (SpatialOperationComboBox.SelectedItem == null) { return; }

            // Remove any currently displayed result.

            // Polygon geometry from the input graphics.
            Geometry polygonOne = _graphicOne.Geometry;
            Geometry polygonTwo = _graphicTwo.Geometry;

            // Result polygon for spatial operations.
            Geometry resultPolygon = null;

            // Run the selected spatial operation on the polygon graphics and get the result geometry.
            string operation = (string)SpatialOperationComboBox.SelectedItem;
            switch (operation)
                case "Union":
                    resultPolygon = GeometryEngine.Union(polygonOne, polygonTwo);
                case "Difference":
                    resultPolygon = GeometryEngine.Difference(polygonOne, polygonTwo);
                case "Symmetric difference":
                    resultPolygon = GeometryEngine.SymmetricDifference(polygonOne, polygonTwo);
                case "Intersection":
                    resultPolygon = GeometryEngine.Intersection(polygonOne, polygonTwo);

            // Create a black outline symbol to use for the result polygon.
            SimpleLineSymbol outlineSymbol = new SimpleLineSymbol(SimpleLineSymbolStyle.Solid, Colors.Black, 1);

            // Create a solid red fill symbol for the result polygon graphic.
            SimpleFillSymbol resultSymbol = new SimpleFillSymbol(SimpleFillSymbolStyle.Solid, Colors.Red, outlineSymbol);

            // Create the result polygon graphic and add it to the graphics overlay.
            _resultGraphic = new Graphic(resultPolygon, resultSymbol);

        private void ResetOperationButton_Clicked(object sender, System.EventArgs e)
            // Remove any currently displayed result.

            // Clear the selected spatial operation.
            SpatialOperationComboBox.SelectedIndex = -1;

        private void CreatePolygonsOverlay()
            // Create a black outline symbol to use for the polygons.
            SimpleLineSymbol outlineSymbol = new SimpleLineSymbol(SimpleLineSymbolStyle.Solid, Colors.Black, 1);

            // Create a point collection to define polygon vertices.
            PointCollection polygonVertices = new PointCollection(SpatialReferences.WebMercator)
                new MapPoint(-13960, 6709400),
                new MapPoint(-14660, 6710000),
                new MapPoint(-13760, 6710730),
                new MapPoint(-13300, 6710500),
                new MapPoint(-13160, 6710100)

            // Create a polygon graphic with a blue fill.
            SimpleFillSymbol fillSymbol = new SimpleFillSymbol(SimpleFillSymbolStyle.Vertical, Colors.Blue, outlineSymbol);
            Polygon polygonOne = new Polygon(polygonVertices);
            _graphicOne = new Graphic(polygonOne, fillSymbol);

            // Create a point collection to define outer polygon ring vertices.
            PointCollection outerRingVerticesCollection = new PointCollection(SpatialReferences.WebMercator)
                new MapPoint(-13060, 6711030),
                new MapPoint(-12160, 6710730),
                new MapPoint(-13160, 6709700),
                new MapPoint(-14560, 6710730)

            // Create a point collection to define inner polygon ring vertices ("donut hole").
            PointCollection innerRingVerticesCollection = new PointCollection(SpatialReferences.WebMercator)
                new MapPoint(-13060, 6710910),
                new MapPoint(-14160, 6710630),
                new MapPoint(-13160, 6709900),
                new MapPoint(-12450, 6710660)

            // Create a list to contain the inner and outer ring point collections.
            List<PointCollection> polygonParts = new List<PointCollection>

            // Create a polygon graphic with a green fill.
            fillSymbol = new SimpleFillSymbol(SimpleFillSymbolStyle.Horizontal, Colors.Green, outlineSymbol);
            _graphicTwo = new Graphic(new Polygon(polygonParts), fillSymbol);

            // Create a graphics overlay in the map view to hold the polygons.
            _polygonsOverlay = new GraphicsOverlay();

            // Add the polygons to the graphics overlay.