Blend renderer

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Blend a hillshade with a raster by specifying the elevation data. The resulting raster looks similar to the original raster, but with some terrain shading, giving it a textured look.

Image of blend renderer

Use case

BlendRenderer can be used to apply a color ramp to a hillshade to emphasize areas of high or low elevation. A BlendRenderer can also be used to add a hillshade effect to aerial or satellite imagery, thereby making changes in elevation more visible.

How to use the sample

Choose and adjust the altitude, azimuth, slope type, and color ramp type settings to update the image.

How it works

  1. Create a Raster object from a raster file.
  2. Create a RasterLayer object from the raster.
  3. Create a Basemap object from the raster layer and set it to the map.
  4. Create another Raster object for elevation from a grayscale raster file.
  5. Create a BlendRenderer object, specifying the elevation raster, color ramp, and other properties.
    • If you specify a non-null color ramp, use the elevation raster as the base raster in addition to the elevation raster parameter. That way, the color ramp is used instead of the satellite imagery.
  6. Set the blend renderer to the raster layer.

Relevant API

  • BlendRenderer
  • ColorRamp
  • Raster
  • RasterLayer

Offline data

This sample uses the Shasta elevation image collection.

Tags

color ramp, elevation, hillshade, image, raster, visualization

Sample Code

ChangeBlendRenderer.xaml.csChangeBlendRenderer.xaml.csChangeBlendRenderer.xaml
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// 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: 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 ArcGIS.Samples.Managers;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Rasters;
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using System.Windows;

namespace ArcGIS.WPF.Samples.ChangeBlendRenderer
{
    [ArcGIS.Samples.Shared.Attributes.Sample(
        name: "Blend renderer",
        category: "Layers",
        description: "Blend a hillshade with a raster by specifying the elevation data. The resulting raster looks similar to the original raster, but with some terrain shading, giving it a textured look.",
        instructions: "Choose and adjust the altitude, azimuth, slope type, and color ramp type settings to update the image.",
        tags: new[] { "color ramp", "elevation", "hillshade", "image", "raster", "visualization" })]
    [ArcGIS.Samples.Shared.Attributes.OfflineData("7c4c679ab06a4df19dc497f577f111bd",
        "caeef9aa78534760b07158bb8e068462")]
    public partial class ChangeBlendRenderer
    {
        public ChangeBlendRenderer()
        {
            InitializeComponent();

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

        private async Task Initialize()
        {
            // Update the preset color ramp type options and select the first one.
            ColorRamps.ItemsSource = Enum.GetNames(typeof(PresetColorRampType));
            ColorRamps.SelectedIndex = 0;

            // Update the slope options and select the first one.
            SlopeTypes.ItemsSource = Enum.GetNames(typeof(SlopeType));
            SlopeTypes.SelectedIndex = 0;

            // Load the raster file using a path on disk.
            Raster myRasterImagery = new Raster(GetRasterPath_Imagery());

            // Create the raster layer from the raster.
            RasterLayer myRasterLayerImagery = new RasterLayer(myRasterImagery);

            // Create a new map using the raster layer as the base map.
            Map myMap = new Map(new Basemap(myRasterLayerImagery));

            try
            {
                // Wait for the layer to load - this enabled being able to obtain the extent information
                // of the raster layer.
                await myRasterLayerImagery.LoadAsync();

                // Create a new EnvelopeBuilder from the full extent of the raster layer.
                EnvelopeBuilder myEnvelopBuilder = new EnvelopeBuilder(myRasterLayerImagery.FullExtent);

                // Zoom in the extent just a bit so that raster layer encompasses the entire viewable area of the map.
                myEnvelopBuilder.Expand(0.75);

                // Set the viewpoint of the map to the EnvelopeBuilder's extent.
                myMap.InitialViewpoint = new Viewpoint(myEnvelopBuilder.ToGeometry().Extent);

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

                // Wait for the map to load.
                await myMap.LoadAsync();

                // Enable the 'Update Renderer' button now that the map has loaded.
                UpdateRenderer.IsEnabled = true;
            }
            catch (Exception e)
            {
                MessageBox.Show(e.ToString(), "Error");
            }
        }

        private void OnUpdateRendererClicked(object sender, RoutedEventArgs e)
        {
            // Define the RasterLayer that will be used to display in the map.
            RasterLayer rasterLayerForDisplayInMap;

            // Define the ColorRamp that will be used by the BlendRenderer.
            ColorRamp myColorRamp;

            // Based on ColorRamp type chosen by the user, create a different
            // RasterLayer and define the appropriate ColorRamp option.
            if (ColorRamps.SelectedValue.ToString() == "None")
            {
                // The user chose not to use a specific ColorRamp, therefore
                // need to create a RasterLayer based on general imagery (i.e. Shasta.tif)
                // for display in the map and use null for the ColorRamp as one of the
                // parameters in the BlendRenderer constructor.

                // Load the raster file using a path on disk.
                Raster rasterImagery = new Raster(GetRasterPath_Imagery());

                // Create the raster layer from the raster.
                rasterLayerForDisplayInMap = new RasterLayer(rasterImagery);

                // Set up the ColorRamp as being null.
                myColorRamp = null;
            }
            else
            {
                // The user chose a specific ColorRamp (options: are Elevation, DemScreen, DemLight),
                // therefore create a RasterLayer based on an imagery with elevation
                // (i.e. Shasta_Elevation.tif) for display in the map. Also create a ColorRamp
                // based on the user choice, translated into an Enumeration, as one of the parameters
                // in the BlendRenderer constructor.

                // Load the raster file using a path on disk.
                Raster rasterElevation = new Raster(GetRasterPath_Elevation());

                // Create the raster layer from the raster.
                rasterLayerForDisplayInMap = new RasterLayer(rasterElevation);

                // Create a ColorRamp based on the user choice, translated into an Enumeration.
                PresetColorRampType myPresetColorRampType =
                    (PresetColorRampType)Enum.Parse(typeof(PresetColorRampType), ColorRamps.SelectedValue.ToString());
                myColorRamp = ColorRamp.Create(myPresetColorRampType, 256);
            }

            // Define the parameters used by the BlendRenderer constructor.
            Raster rasterForMakingBlendRenderer = new Raster(GetRasterPath_Elevation());
            IEnumerable<double> myOutputMinValues = new List<double> { 9 };
            IEnumerable<double> myOutputMaxValues = new List<double> { 255 };
            IEnumerable<double> mySourceMinValues = new List<double>();
            IEnumerable<double> mySourceMaxValues = new List<double>();
            IEnumerable<double> myNoDataValues = new List<double>();
            IEnumerable<double> myGammas = new List<double>();
            SlopeType mySlopeType = (SlopeType)Enum.Parse(typeof(SlopeType), SlopeTypes.SelectedValue.ToString());

            BlendRenderer myBlendRenderer = new BlendRenderer(
                rasterForMakingBlendRenderer, // elevationRaster - Raster based on a elevation source.
                myOutputMinValues, // outputMinValues - Output stretch values, one for each band.
                myOutputMaxValues, // outputMaxValues - Output stretch values, one for each band.
                mySourceMinValues, // sourceMinValues - Input stretch values, one for each band.
                mySourceMaxValues, // sourceMaxValues - Input stretch values, one for each band.
                myNoDataValues, // noDataValues - NoData values, one for each band.
                myGammas, // gammas - Gamma adjustment.
                myColorRamp, // colorRamp - ColorRamp object to use, could be null.
                AltitudeSlider.Value, // altitude - Altitude angle of the light source.
                AzimuthSlider.Value, // azimuth - Azimuth angle of the light source, measured clockwise from north.
                1, // zfactor - Factor to convert z unit to x,y units, default is 1.
                mySlopeType, // slopeType - Slope Type.
                1, // pixelSizeFactor - Pixel size factor, default is 1.
                1, // pixelSizePower - Pixel size power value, default is 1.
                8); // outputBitDepth - Output bit depth, default is 8-bi.

            // Set the RasterLayer.Renderer to be the BlendRenderer.
            rasterLayerForDisplayInMap.Renderer = myBlendRenderer;

            // Set the new base map to be the RasterLayer with the BlendRenderer applied.
            MyMapView.Map.Basemap = new Basemap(rasterLayerForDisplayInMap);
        }

        private static string GetRasterPath_Imagery()
        {
            return DataManager.GetDataFolder("7c4c679ab06a4df19dc497f577f111bd", "raster-file", "Shasta.tif");
        }

        private static string GetRasterPath_Elevation()
        {
            return DataManager.GetDataFolder("caeef9aa78534760b07158bb8e068462", "Shasta_Elevation.tif");
        }
    }
}

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