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 downloads the following items from ArcGIS Online automatically:

Tags

Elevation, Hillshade, RasterLayer, color ramp, elevation, image, visualization

Sample Code

ChangeBlendRenderer.cs
                                                                                                                                                                                                                                                                                                                                                                     
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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 System;
using System.Collections.Generic;
using ArcGISRuntime.Samples.Managers;
using CoreGraphics;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Rasters;
using Esri.ArcGISRuntime.UI.Controls;
using Foundation;
using UIKit;

namespace ArcGISRuntime.Samples.ChangeBlendRenderer
{
    [Register("ChangeBlendRenderer")]
    [ArcGISRuntime.Samples.Shared.Attributes.OfflineData("7c4c679ab06a4df19dc497f577f111bd", "caeef9aa78534760b07158bb8e068462")]
    [ArcGISRuntime.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[] { "Elevation", "Hillshade", "RasterLayer", "color ramp", "elevation", "image", "visualization" })]
    public class ChangeBlendRenderer : UIViewController
    {
        // Hold references to UI controls.
        private MapView _myMapView;
        private BlendSettingsController _settingsVC;
        private UIBarButtonItem _updateButton;

        public ChangeBlendRenderer()
        {
            Title = "Blend renderer";
        }

        private async void Initialize()
        {
            // Load the raster file using a path on disk.
            Raster rasterImagery = new Raster(DataManager.GetDataFolder("7c4c679ab06a4df19dc497f577f111bd", "raster-file", "Shasta.tif"));

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

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

            try
            {
                // Wait for the layer to load - this enabled being able to obtain the raster layer's extent.
                await rasterLayerImagery.LoadAsync();

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

                // Configure the settings view.
                _settingsVC = new BlendSettingsController(map);

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

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

                // Add map to the map view.
                _myMapView.Map = map;

                // Wait for the map to load.
                await map.LoadAsync();
            }
            catch (Exception e)
            {
                new UIAlertView("Error", e.ToString(), (IUIAlertViewDelegate) null, "OK", null).Show();
            }
        }

        private void UpdateRenderer_Clicked(object sender, EventArgs e)
        {
            UINavigationController controller = new UINavigationController(_settingsVC);
            controller.ModalPresentationStyle = UIModalPresentationStyle.Popover;
            controller.PreferredContentSize = new CGSize(320, 300);
            UIPopoverPresentationController pc = controller.PopoverPresentationController;
            if (pc != null)
            {
                pc.BarButtonItem = (UIBarButtonItem) sender;
                pc.PermittedArrowDirections = UIPopoverArrowDirection.Down;
                pc.Delegate = new PpDelegate();
            }

            PresentViewController(controller, true, null);
        }

        public override void ViewDidLoad()
        {
            base.ViewDidLoad();
            Initialize();
        }

        public override void LoadView()
        {
            // Create the views.
            View = new UIView {BackgroundColor = ApplicationTheme.BackgroundColor};

            _myMapView = new MapView();
            _myMapView.TranslatesAutoresizingMaskIntoConstraints = false;

            _updateButton = new UIBarButtonItem();
            _updateButton.Title = "Update renderer";

            UIToolbar toolbar = new UIToolbar();
            toolbar.TranslatesAutoresizingMaskIntoConstraints = false;
            toolbar.Items = new[]
            {
                new UIBarButtonItem(UIBarButtonSystemItem.FlexibleSpace),
                _updateButton
            };

            // Add the views.
            View.AddSubviews(_myMapView, toolbar);

            // Lay out the views.
            NSLayoutConstraint.ActivateConstraints(new[]
            {
                _myMapView.TopAnchor.ConstraintEqualTo(View.SafeAreaLayoutGuide.TopAnchor),
                _myMapView.LeadingAnchor.ConstraintEqualTo(View.LeadingAnchor),
                _myMapView.TrailingAnchor.ConstraintEqualTo(View.TrailingAnchor),
                _myMapView.BottomAnchor.ConstraintEqualTo(toolbar.TopAnchor),

                toolbar.LeadingAnchor.ConstraintEqualTo(View.LeadingAnchor),
                toolbar.TrailingAnchor.ConstraintEqualTo(View.TrailingAnchor),
                toolbar.BottomAnchor.ConstraintEqualTo(View.SafeAreaLayoutGuide.BottomAnchor)
            });
        }

        public override void ViewWillAppear(bool animated)
        {
            base.ViewWillAppear(animated);

            // Subscribe to events.
            _updateButton.Clicked += UpdateRenderer_Clicked;
        }

        public override void ViewDidDisappear(bool animated)
        {
            base.ViewDidDisappear(animated);

            // Unsubscribe from events, per best practice.
            _updateButton.Clicked -= UpdateRenderer_Clicked;
        }

        // Force popover to display on iPhone.
        private class PpDelegate : UIPopoverPresentationControllerDelegate
        {
            public override UIModalPresentationStyle GetAdaptivePresentationStyle(
                UIPresentationController forPresentationController) => UIModalPresentationStyle.None;

            public override UIModalPresentationStyle GetAdaptivePresentationStyle(UIPresentationController controller,
                UITraitCollection traitCollection) => UIModalPresentationStyle.None;
        }
    }

    public class BlendSettingsController : UIViewController
    {
        // Hold references to UI controls.
        private readonly Map _map;
        private UISegmentedControl _slopeTypesPicker;
        private UISegmentedControl _colorRampsPicker;
        private UISlider _altitudeSlider;
        private UISlider _azimuthSlider;

        public BlendSettingsController(Map map)
        {
            _map = map;
            Title = "Hillshade settings";
        }

        public override void LoadView()
        {
            // Create the views.
            View = new UIView() { BackgroundColor = ApplicationTheme.BackgroundColor };

            UIScrollView scrollView = new UIScrollView();
            scrollView.TranslatesAutoresizingMaskIntoConstraints = false;

            View.AddSubviews(scrollView);

            scrollView.TopAnchor.ConstraintEqualTo(View.TopAnchor).Active = true;
            scrollView.LeadingAnchor.ConstraintEqualTo(View.LeadingAnchor).Active = true;
            scrollView.TrailingAnchor.ConstraintEqualTo(View.TrailingAnchor).Active = true;
            scrollView.BottomAnchor.ConstraintEqualTo(View.BottomAnchor).Active = true;

            UIStackView formContainer = new UIStackView();
            formContainer.TranslatesAutoresizingMaskIntoConstraints = false;
            formContainer.Spacing = 8;
            formContainer.LayoutMarginsRelativeArrangement = true;
            formContainer.Alignment = UIStackViewAlignment.Fill;
            formContainer.LayoutMargins = new UIEdgeInsets(8, 8, 8, 8);
            formContainer.Axis = UILayoutConstraintAxis.Vertical;
            formContainer.WidthAnchor.ConstraintEqualTo(320).Active = true;

            // Form controls here.
            UILabel slopeTypesLabel = new UILabel();
            slopeTypesLabel.TranslatesAutoresizingMaskIntoConstraints = false;
            slopeTypesLabel.Text = "Slope type:";
            formContainer.AddArrangedSubview(slopeTypesLabel);

            _slopeTypesPicker = new UISegmentedControl(Enum.GetNames(typeof(SlopeType)));
            _slopeTypesPicker.TranslatesAutoresizingMaskIntoConstraints = false;
            _slopeTypesPicker.SelectedSegment = 0;
            formContainer.AddArrangedSubview(_slopeTypesPicker);

            UILabel colorRampsLabel = new UILabel();
            colorRampsLabel.TranslatesAutoresizingMaskIntoConstraints = false;
            colorRampsLabel.Text = "Color ramp:";
            formContainer.AddArrangedSubview(colorRampsLabel);

            _colorRampsPicker = new UISegmentedControl(Enum.GetNames(typeof(PresetColorRampType)));
            _colorRampsPicker.TranslatesAutoresizingMaskIntoConstraints = false;
            _colorRampsPicker.SelectedSegment = 0;
            formContainer.AddArrangedSubview(_colorRampsPicker);

            UILabel altitudeLabel = new UILabel();
            altitudeLabel.TranslatesAutoresizingMaskIntoConstraints = false;
            altitudeLabel.Text = "Altitude:";
            formContainer.AddArrangedSubview(altitudeLabel);

            _altitudeSlider = new UISlider();
            _altitudeSlider.TranslatesAutoresizingMaskIntoConstraints = false;
            _altitudeSlider.MinValue = 0;
            _altitudeSlider.MaxValue = 90;
            _altitudeSlider.Value = 45;
            formContainer.AddArrangedSubview(_altitudeSlider);

            UILabel azimuthLabel = new UILabel();
            azimuthLabel.TranslatesAutoresizingMaskIntoConstraints = false;
            azimuthLabel.Text = "Azimuth:";
            formContainer.AddArrangedSubview(azimuthLabel);

            _azimuthSlider = new UISlider();
            _azimuthSlider.TranslatesAutoresizingMaskIntoConstraints = false;
            _azimuthSlider.MinValue = 0;
            _azimuthSlider.MaxValue = 360;
            _azimuthSlider.Value = 180;
            formContainer.AddArrangedSubview(_azimuthSlider);

            // Add the views.
            scrollView.AddSubview(formContainer);

            // Put the apply button in the top-right part of the popover.
            NavigationItem.RightBarButtonItem = new UIBarButtonItem("Apply", UIBarButtonItemStyle.Plain, UpdateRendererButton_Clicked);

            // Lay out the views.
            formContainer.TopAnchor.ConstraintEqualTo(scrollView.TopAnchor).Active = true;
            formContainer.LeadingAnchor.ConstraintEqualTo(scrollView.LeadingAnchor).Active = true;
            formContainer.TrailingAnchor.ConstraintEqualTo(scrollView.TrailingAnchor).Active = true;
            formContainer.BottomAnchor.ConstraintEqualTo(scrollView.BottomAnchor).Active = true;

            // Disable horizontal scrolling.
            formContainer.WidthAnchor.ConstraintEqualTo(scrollView.WidthAnchor).Active = true;
        }

        private void UpdateRendererButton_Clicked(object sender, EventArgs e)
        {
            try
            {
                // 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 colorRamp;

                // Get the user choice for the ColorRamps.
                string selection = Enum.GetNames(typeof(PresetColorRampType))[_colorRampsPicker.SelectedSegment];

                // Based on ColorRamp type chosen by the user, create a different
                // RasterLayer and define the appropriate ColorRamp option.
                if (selection == "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(DataManager.GetDataFolder("7c4c679ab06a4df19dc497f577f111bd", "raster-file", "Shasta.tif"));

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

                    // Set up the ColorRamp as being null.
                    colorRamp = 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(DataManager.GetDataFolder("caeef9aa78534760b07158bb8e068462", "Shasta_Elevation.tif"));

                    // 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), selection);
                    colorRamp = ColorRamp.Create(myPresetColorRampType, 256);
                }

                // Define the parameters used by the BlendRenderer constructor.
                Raster rasterForMakingBlendRenderer = new Raster(DataManager.GetDataFolder("caeef9aa78534760b07158bb8e068462", "Shasta_Elevation.tif"));
                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>();

                // Get the user choice for the SlopeType.
                string slopeSelection = Enum.GetNames(typeof(SlopeType))[_slopeTypesPicker.SelectedSegment];
                SlopeType mySlopeType = (SlopeType) Enum.Parse(typeof(SlopeType), slopeSelection);

                rasterLayerForDisplayInMap.Renderer = 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.
                    colorRamp, // 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-bit.

                // Set the new base map to be the RasterLayer with the BlendRenderer applied.
                _map.Basemap = new Basemap(rasterLayerForDisplayInMap);
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex);
            }
        }
    }
}

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