Perform spatial operations

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

Tags

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

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<?xml version="1.0" encoding="utf-8" ?>
<ContentPage x:Class="ArcGISRuntimeXamarin.Samples.SpatialOperations.SpatialOperations"
             xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:esriUI="clr-namespace:Esri.ArcGISRuntime.Xamarin.Forms;assembly=Esri.ArcGISRuntime.Xamarin.Forms">
    <Grid>
        <esriUI:MapView x:Name="MyMapView" />
        <Frame Margin="30"
               Padding="10"
               BackgroundColor="WhiteSmoke"
               HorizontalOptions="CenterAndExpand"
               VerticalOptions="Start"
               WidthRequest="275">
            <StackLayout>
                <Label Text="Select a spatial operation:">
                    <Label.TextColor>
                        <OnPlatform x:TypeArguments="Color">
                            <On Platform="Android" Value="DarkGray" />
                        </OnPlatform>
                    </Label.TextColor>
                </Label>
                <Picker x:Name="SpatialOperationComboBox"
                        Margin="0,5"
                        SelectedIndexChanged="SpatialOperationComboBox_SelectedIndexChanged"
                        VerticalOptions="CenterAndExpand"
                        WidthRequest="253">
                    <Picker.BackgroundColor>
                        <OnPlatform x:TypeArguments="Color">
                            <On Platform="Android" Value="DarkGray" />
                        </OnPlatform>
                    </Picker.BackgroundColor>
                </Picker>
                <Button x:Name="ResetOperationButton"
                        Clicked="ResetOperationButton_Clicked"
                        Text="Reset operation"
                        WidthRequest="253" />
            </StackLayout>
        </Frame>
    </Grid>
</ContentPage>