Feature layer extrusion

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Extrude features based on their attributes.

Image of feature layer extrusion

Use case

Extrusion is the process of stretching a flat, 2D shape vertically to create a 3D object in a scene. For example, you can extrude building polygons by a height value to create three-dimensional building shapes.

How to use the sample

Press the button to switch between using population density and total population for extrusion. Higher extrusion directly corresponds to higher attribute values.

How it works

  1. Create a ServiceFeatureTable from a URL.
  2. Create a feature layer from the service feature table.

    • Make sure to set the rendering mode to dynamic.
  3. Apply a SimpleRenderer to the feature layer.
  4. Set ExtrusionMode of render, renderer.SceneProperties.ExtrusionMode = SceneProperties.ExtrusionMode.BaseHeight.
  5. Set extrusion expression of renderer, renderer.SceneProperties.ExtrusionExpression = "[POP2007]/ 10".

Relevant API

  • ExtrusionExpression
  • ExtrusionMode
  • FeatureLayer
  • FeatureLayer
  • SceneProperties
  • ServiceFeatureTable
  • SimpleRenderer

Tags

3D, extrude, extrusion, extrusion expression, height, renderer, scene

Sample Code

FeatureLayerExtrusion.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 Esri.ArcGISRuntime.Data;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.UI;
using Esri.ArcGISRuntime.UI.Controls;
using Foundation;
using System;
using System.Drawing;
using UIKit;

namespace ArcGISRuntime.Samples.FeatureLayerExtrusion
{
    [Register("FeatureLayerExtrusion")]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        name: "Feature layer extrusion",
        category: "Symbology",
        description: "Extrude features based on their attributes.",
        instructions: "Press the button to switch between using population density and total population for extrusion. Higher extrusion directly corresponds to higher attribute values.",
        tags: new[] { "3D", "extrude", "extrusion", "extrusion expression", "height", "renderer", "scene" })]
    public class FeatureLayerExtrusion : UIViewController
    {
        // Hold references to UI controls.
        private SceneView _mySceneView;
        private UISegmentedControl _extrusionFieldButton;

        public FeatureLayerExtrusion()
        {
            Title = "Feature layer extrusion";
        }

        private void Initialize()
        {
            try
            {
                // Define the URI for the service feature table (US state polygons).
                Uri featureTableUri = new Uri("https://sampleserver6.arcgisonline.com/arcgis/rest/services/Census/MapServer/3");

                // Create a new service feature table from the URI.
                ServiceFeatureTable censusServiceFeatureTable = new ServiceFeatureTable(featureTableUri);

                // Create a new feature layer from the service feature table.
                FeatureLayer censusFeatureLayer = new FeatureLayer(censusServiceFeatureTable)
                {
                    // Set the rendering mode of the feature layer to be dynamic (needed for extrusion to work).
                    RenderingMode = FeatureRenderingMode.Dynamic
                };

                // Create a new simple line symbol for the feature layer.
                SimpleLineSymbol lineSymbol = new SimpleLineSymbol(SimpleLineSymbolStyle.Solid, Color.Black, 1);

                // Create a new simple fill symbol for the feature layer.
                SimpleFillSymbol fillSymbol = new SimpleFillSymbol(SimpleFillSymbolStyle.Solid, Color.Blue, lineSymbol);

                // Create a new simple renderer for the feature layer.
                SimpleRenderer renderer = new SimpleRenderer(fillSymbol);

                // Get the scene properties from the simple renderer.
                RendererSceneProperties sceneProperties = renderer.SceneProperties;

                // Set the extrusion mode for the scene properties.
                sceneProperties.ExtrusionMode = ExtrusionMode.AbsoluteHeight;

                // Set the initial extrusion expression.
                sceneProperties.ExtrusionExpression = "[POP2007] / 10";

                // Set the feature layer's renderer to the define simple renderer.
                censusFeatureLayer.Renderer = renderer;

                // Create a new scene with a topographic basemap.
                Scene myScene = new Scene(BasemapType.Topographic);

                // Set the scene view's scene to the newly create one.
                _mySceneView.Scene = myScene;

                // Add the feature layer to the scene's operational layer collection.
                myScene.OperationalLayers.Add(censusFeatureLayer);

                // Create a new map point to define where to look on the scene view.
                MapPoint myMapPoint = new MapPoint(-10974490, 4814376, 0, SpatialReferences.WebMercator);

                // Create and use an orbit location camera controller defined by a point and distance.
                _mySceneView.CameraController = new OrbitLocationCameraController(myMapPoint, 20000000);
            }
            catch (Exception ex)
            {
                // Something went wrong, display the error.
                UIAlertController alert = UIAlertController.Create("Error", ex.Message, UIAlertControllerStyle.Alert);
                alert.AddAction(UIAlertAction.Create("OK", UIAlertActionStyle.Default, null));
                PresentViewController(alert, true, null);
            }
        }

        private void ToggleExtrusionButton_Clicked(object sender, EventArgs e)
        {
            // Get the first layer from the scene view's operation layers, it should be a feature layer.
            FeatureLayer censusFeatureLayer = (FeatureLayer)_mySceneView.Scene.OperationalLayers[0];

            // Get the renderer from the feature layer.
            Renderer censusRenderer = censusFeatureLayer.Renderer;

            // Get the scene properties from the feature layer's renderer.
            RendererSceneProperties sceneProperties = censusRenderer.SceneProperties;

            // Toggle the feature layer's scene properties renderer extrusion expression and change the button text.
            if (((UISegmentedControl)sender).SelectedSegment == 0)
            {
                // An offset of 100000 is added to ensure that polygons for large areas (like Alaska)
                // with low populations will be extruded above the curvature of the Earth.
                sceneProperties.ExtrusionExpression = "[POP07_SQMI] * 5000 + 100000";
            }
            else
            {
                sceneProperties.ExtrusionExpression = "[POP2007] / 10";
            }
        }

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

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

            _mySceneView = new SceneView { TranslatesAutoresizingMaskIntoConstraints = false };

            _extrusionFieldButton = new UISegmentedControl("Population density", "Total population")
            {
                BackgroundColor = ApplicationTheme.BackgroundColor,
                SelectedSegment = 1,
                TranslatesAutoresizingMaskIntoConstraints = false
            };

            // Add the views.
            View.AddSubviews(_mySceneView, _extrusionFieldButton);

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

                _extrusionFieldButton.LeadingAnchor.ConstraintEqualTo(View.LayoutMarginsGuide.LeadingAnchor),
                _extrusionFieldButton.TrailingAnchor.ConstraintEqualTo(View.LayoutMarginsGuide.TrailingAnchor),
                _extrusionFieldButton.TopAnchor.ConstraintEqualTo(View.SafeAreaLayoutGuide.TopAnchor, 8)
            });
        }

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

            // Subscribe to events.
            _extrusionFieldButton.ValueChanged += ToggleExtrusionButton_Clicked;
        }

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

            // Unsubscribe from events, per best practice.
            _extrusionFieldButton.ValueChanged -= ToggleExtrusionButton_Clicked;
        }
    }
}

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