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ArcGIS Runtime SDK for .NET

Raster rendering rule

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

Display a raster on a map and apply different rendering rules to that raster.

screenshot

Use case

Raster images whose individual pixels represent elevation values can be rendered in a number of different ways, including representation of slope, aspect, hillshade, and shaded relief. Applying these different rendering rules to the same raster allows for a powerful visual analysis of the data. For example, a geologist could interrogate the raster image to map subtle geological features on a landscape, which may become apparent only through comparing the raster when rendered using several different rules.

How to use the sample

Run the sample and use the button to select a rendering rule.

How it works

  1. Create an ImageServiceRaster using a URL to an online image service.
  2. After loading the raster, use imageServiceRaster.ServiceInfo.RenderingRuleInfos to get a list of RenderingRuleInfo supported by the service.
  3. Choose a rendering rule info to apply and use it to create a RenderingRule.
  4. Create a new ImageServiceRaster using the same URL.
  5. Apply the rendering rule to the new raster.
  6. Create a RasterLayer from the raster for display.

Relevant API

  • ImageServiceRaster
  • RasterLayer
  • RenderingRule

About the data

This raster image service contains 9 LAS files covering Charlotte, North Carolina's downtown area. The lidar data was collected in 2007. Four Raster Rules are available for selection: None, RFTAspectColor, RFTHillshade, and RFTShadedReliefElevationColorRamp.

Additional information

Image service rasters of any type can have rendering rules applied to them; they need not necessarily be elevation rasters. For a list of raster functions and the syntax for rendering rules, see the ArcGIS REST API documentation: https://developers.arcgis.com/documentation/common-data-types/raster-function-objects.htm.

Tags

raster, rendering rules, visualization

Sample Code

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage 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"
             xmlns:mapping="clr-namespace:Esri.ArcGISRuntime.Mapping;assembly=Esri.ArcGISRuntime" 
             x:Class="ArcGISRuntime.Samples.RasterRenderingRule.RasterRenderingRule">
  <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="*" />
            <RowDefinition Height="auto" />
        </Grid.RowDefinitions>
        <esriUI:MapView x:Name="MyMapView" />
        <Button x:Name="changeRenderingRule" Text="Change Rendering Rule" Clicked="OnChangeRenderingRuleButtonClicked" Grid.Row="1"/>
    </Grid>
</ContentPage>
// Copyright 2017 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: http://www.apache.org/licenses/LICENSE-2.0
//
// 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.ArcGISServices;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Rasters;
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Xamarin.Forms;

namespace ArcGISRuntime.Samples.RasterRenderingRule
{
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        "Raster rendering rule",
        "Layers",
        "This sample demonstrates how to create an `ImageServiceRaster`, fetch the `RenderingRule`s from the service info, and use a `RenderingRule` to create an `ImageServiceRaster` and add it to a raster layer.",
        "")]
    public partial class RasterRenderingRule : ContentPage
    {
        public RasterRenderingRule()
        {
            InitializeComponent();

            // Create the UI, setup the control references and execute initialization
            Initialize();
        }

        // Create an empty read-only list for the various rendering rules of the image service raster
        private IReadOnlyList<RenderingRuleInfo> _myReadOnlyListRenderRuleInfos;

        // Create a Uri for the image server
        private Uri _myUri = new Uri("https://sampleserver6.arcgisonline.com/arcgis/rest/services/CharlotteLAS/ImageServer");

        // Create a list to store the names of the rendering rule info for the image service raster
        private List<string> _names = new List<string>();

        private async void Initialize()
        {
            // Assign a new map to the MapView
            MyMapView.Map = new Map
            {

                // Set the basemap to Streets
                Basemap = Basemap.CreateStreets()
            };

            // Create a new image service raster from the Uri
            ImageServiceRaster myImageServiceRaster = new ImageServiceRaster(_myUri);

            try
            {
                // Load the image service raster
                await myImageServiceRaster.LoadAsync();

                // Get the ArcGIS image service info (metadata) from the image service raster
                ArcGISImageServiceInfo myArcGISImageServiceInfo = myImageServiceRaster.ServiceInfo;

                // Get the full extent envelope of the image service raster (the Charlotte, NC area)
                Envelope myEnvelope = myArcGISImageServiceInfo.FullExtent;

                // Define a new view point from the full extent envelope
                Viewpoint myViewPoint = new Viewpoint(myEnvelope);

                // Zoom to the area of the full extent envelope of the image service raster
                await MyMapView.SetViewpointAsync(myViewPoint);

                // Get the rendering rule info (i.e. definitions of how the image should be drawn) info from the image service raster
                _myReadOnlyListRenderRuleInfos = myArcGISImageServiceInfo.RenderingRuleInfos;

                // Loop through each rendering rule info
                foreach (RenderingRuleInfo myRenderingRuleInfo in _myReadOnlyListRenderRuleInfos)
                {
                    // Get the name of the rendering rule info
                    string myRenderingRuleName = myRenderingRuleInfo.Name;

                    // Add the name of the rendering rule info into the list of names
                    _names.Add(myRenderingRuleName);
                }

                // Call the function to display the image service raster based up on user choice of rendering rules
                await ChangeRenderingRuleAsync();
            }
            catch (Exception e)
            {
                await Application.Current.MainPage.DisplayAlert("Error", e.ToString(), "OK");
            }
        }

        private async Task ChangeRenderingRuleAsync()
        {
            // Display a picker to the user to choose among the available rendering rules for the image service raster
            string myRenderingRuleInfoName = await ((Page)Parent).DisplayActionSheet("Select a Rendering Rule", "Cancel", null, _names.ToArray());

            // Loop through each rendering rule info in the image service raster
            foreach (RenderingRuleInfo myRenderingRuleInfo in _myReadOnlyListRenderRuleInfos)
            {
                // Get the name of the rendering rule info
                string myRenderingRuleName = myRenderingRuleInfo.Name;

                // If the name of the rendering rule info matches what was chosen by the user, proceed
                if (myRenderingRuleName == myRenderingRuleInfoName)
                {
                    // Create a new rendering rule from the rendering rule info
                    RenderingRule myRenderingRule = new RenderingRule(myRenderingRuleInfo);

                    // Create a new image service raster
                    ImageServiceRaster myImageServiceRaster = new ImageServiceRaster(_myUri)
                    {

                        // Set the image service raster's rendering rule to the rendering rule created earlier
                        RenderingRule = myRenderingRule
                    };

                    // Create a new raster layer from the image service raster
                    RasterLayer myRasterLayer = new RasterLayer(myImageServiceRaster);

                    // Add the raster layer to the operational layers of the  map view
                    MyMapView.Map.OperationalLayers.Add(myRasterLayer);
                }
            }
        }

        private async void OnChangeRenderingRuleButtonClicked(object sender, EventArgs e)
        {
            // Call the function to display the image service raster based up on user choice of rendering rules
            await ChangeRenderingRuleAsync();
        }
    }
}