Feature layer extrusion

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Extrude features based on their attributes.

Feature layer extrusion sample

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

Tap the bottom buttons to switch between using population density and total population for extrusion. Higher extrusion directly corresponds to higher attribute values.

How it works

  1. Create an AGSServiceFeatureTable from a URL.
  2. Create an AGSFeatureLayer from the service feature table.

    • Make sure to set the renderingMode property to dynamic.
  3. Apply an AGSSimpleRenderer to the feature layer.
  4. Set the renderer's extrusionMode property to absoluteHeight.
  5. Set the renderer's extrusionExpression property to "[POP2007]/ 10".

Relevant API

  • AGSExtrusionMode
  • AGSFeatureLayer
  • AGSRendererSceneProperties
  • AGSServiceFeatureTable
  • AGSSimpleRenderer

Tags

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

Sample Code

FeatureLayerExtrusionViewController.swift
                                                                                                
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// 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.

import UIKit
import ArcGIS

/// A view controller that manages the interface of the Feature Layer Extrusion
/// sample.
class FeatureLayerExtrusionViewController: UIViewController {
    /// The scene displayed in the scene view.
    let scene: AGSScene
    /// The renderer of the feature layer.
    let renderer: AGSRenderer

    required init?(coder: NSCoder) {
        scene = AGSScene(basemapType: .topographic)

        /// The url of the States layer of the Census Map Service.
        let censusMapServiceStatesLayerURL = URL(string: "https://sampleserver6.arcgisonline.com/arcgis/rest/services/Census/MapServer/3")!
        // Create service feature table from US census feature service.
        let table = AGSServiceFeatureTable(url: censusMapServiceStatesLayerURL)
        // Create feature layer from service feature table.
        let layer = AGSFeatureLayer(featureTable: table)
        // Feature layer must be rendered dynamically for extrusion to work.
        layer.renderingMode = .dynamic
        // Setup the symbols used to display the features (US states) from the table.
        let lineSymbol = AGSSimpleLineSymbol(style: .solid, color: .blue, width: 1.0)
        let fillSymbol = AGSSimpleFillSymbol(style: .solid, color: .blue, outline: lineSymbol)
        renderer = AGSSimpleRenderer(symbol: fillSymbol)
        if let sceneProperties = renderer.sceneProperties {
            sceneProperties.extrusionMode = .absoluteHeight
            sceneProperties.extrusionExpression = Statistic.totalPopulation.extrusionExpression
        }

        // Set the renderer on the layer and add the layer to the scene.
        layer.renderer = renderer
        scene.operationalLayers.add(layer)

        super.init(coder: coder)
    }

    /// The scene view managed by the view controller.
    @IBOutlet weak var sceneView: AGSSceneView!

    override func viewDidLoad() {
        super.viewDidLoad()

        // Adds the source code button item to the right of navigation bar.
        (self.navigationItem.rightBarButtonItem as! SourceCodeBarButtonItem).filenames = ["FeatureLayerExtrusionViewController"]

        sceneView.scene = scene

        // Set the scene view's viewpoint.
        let distance = 12_940_924.0
        let point = AGSPoint(x: -99.659448, y: 20.513652, z: distance, spatialReference: .wgs84())
        let camera = AGSCamera(lookAt: point, distance: 0, heading: 0, pitch: 15, roll: 0)
        let viewpoint = AGSViewpoint(center: point, scale: distance, camera: camera)
        sceneView.setViewpoint(viewpoint)
    }

    enum Statistic: Int {
        case totalPopulation
        case populationDensity

        /// The extrusion expression for the statistic.
        var extrusionExpression: String {
            switch self {
            case .totalPopulation:
                return "[POP2007]/ 10"
            case .populationDensity:
                // The offset makes the extrusion look better over Alaska.
                let offset = 100_000
                return "([POP07_SQMI] * 5000) + \(offset)"
            }
        }
    }

    @IBAction func extrusionAction(_ sender: UISegmentedControl) {
        if let statistic = Statistic(rawValue: sender.selectedSegmentIndex) {
            renderer.sceneProperties?.extrusionExpression = statistic.extrusionExpression
        } else {
            assertionFailure("Selected segment does not correspond to a statistic")
        }
    }
}

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