Measure a distance in 3D

Learn how to evaluate the horizontal, vertical, and direct distances between two points in a 3D Scene.

A distance measurement analysis is a type of measurement analysis that calculates and displays the distance between start point and end point locations. The analysis evaluates the vertical, horizontal, and direct distances between the two 3D points and renders a measurement visualization on-screen.

In this tutorial you will perform and display a distance measurement analysis in a web scene. Using the distance measurement analysis you will measure distances between hotspots in the Yosemite Valley.

Prerequisites

Before starting this tutorial:

You need an ArcGIS Location Platform or ArcGIS Online account.
Your system meets the system requirements.

Steps

Open the Xcode project

To start this tutorial, first complete the Display a web scene tutorial or download and unzip the solution.
Open the .xcodeproj file in Xcode.
If you downloaded the solution, get an access token and set the API key.
An API Key gives your app access to secure resources used in this tutorial.
1. Go to the Create an API key tutorial to obtain a new API key access token using your ArcGIS Location Platform or ArcGIS Online account. Ensure that the following privilege is enabled: Location services > Basemaps > Basemap styles service. Copy the access token as it will be used in the next step.
2. In Xcode, in the Project Navigator, click AppDelegate.swift.
3. In the editor, set the APIKey property on the AGSArcGISRuntimeEnvironment with your access token.
  AppDelegate.swift
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  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool { AGSArcGISRuntimeEnvironment.apiKey = "YOUR_ACCESS_TOKEN" return true }
  Expand
  Warning
  The access token is stored directly in the code as a convenience for this tutorial. Storing access tokens in the source code is not best practice.

Get the web scene item ID

You can use ArcGIS tools to create and view web scenes. Use the Scene Viewer to identify the web scene item ID. This item ID will be used later in the tutorial.

Go to the Yosemite Valley Hotspots web scene in the Scene Viewer in ArcGIS Online. This web scene displays terrain and hotspots in the Yosemite Valley.
Make a note of the item ID at the end of the browser's URL. The item ID should be 7558ee942b2547019f66885c44d4f0b1.

Update the scene

In Xcode, in the Project Navigator, click ViewController.swift.

In the editor, modify the setupScene() method to create an AGSScene for the web scene. To do this, create a portal item providing the web scene's item ID and an AGSPortal referencing ArcGIS Online.

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Change line    private func setupScene() {
        let scene: AGSScene = {
            let portal = AGSPortal.arcGISOnline(withLoginRequired: false)

            let item = AGSPortalItem(portal: portal, itemID: "7558ee942b2547019f66885c44d4f0b1")

            return AGSScene(item: item)
        }()
        sceneView.scene = scene

    }
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Add a UI to control the distance measurement analysis

To control the distance measurement analysis, some UI is required.

Define a private method named setupUI(). Create a "Clear" button and assign it to the navigation bar. The clear button removes the distance measurement analysis from the scene. You set an action on the clear button using a selector for a method that will be added in a later step.

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        navigationItem.title = "Long press and drag."
        let clear = UIBarButtonItem(title: "Clear", style: .plain, target: self, action: #selector(clearScene))
        navigationItem.rightBarButtonItem = clear
    }

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Define a method named clearScene(_:) and assign it the @objc keyword. This method is performed when the user taps the clear button. The @objc method keyword exposes the method to Objective-C, a necessary step for using the UIBarButtonItem API.

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        navigationItem.title = "Long press and drag."
        let clear = UIBarButtonItem(title: "Clear", style: .plain, target: self, action: #selector(clearScene))
        navigationItem.rightBarButtonItem = clear
    }

    @objc
    func clearScene(_ sender: UIBarButtonItem) {

    }
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In viewDidLoad(), call the method setupUI().

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        super.viewDidLoad()
        setupScene()

        setupUI()

    }
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In Xcode, in the Project Navigator, click Main.storyboard.
In the editor, select ViewController. In the menu bar, click Editor > Embed In > Navigation Controller.

Embedding ViewController within a Navigation Controller will place a navigation bar at the top of ViewController. Inside the navigation bar you will find the UI elements.
Check that your UI is set up properly. Press <Command+R> to run the app. You should see a "Clear" button contained by the navigation bar, the default title should be displayed, and the app should load the Yosemite Valley Hotspots web scene.

Format measurements for readability

In Xcode, in the Project Navigator, click ViewController.swift.

In the editor, create a private static MeasurementFormatter named measurementFormatter. The measurement formatter is used to convert measurement values into strings that are in a format localized to the user's device.

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        let measurementFormatter = MeasurementFormatter()
        measurementFormatter.numberFormatter.minimumFractionDigits = 2
        measurementFormatter.numberFormatter.maximumFractionDigits = 2
        return measurementFormatter
    }()

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Define a private method named setTitleForDistanceMeasurements(direct:horizontal:vertical:). This method is used to format a string to communicate the direct, horizontal, and vertical measurements to the user, placing the results in the navigation bar's title.

Because setTitleForDistanceMeasurements performs a UI operation and you cannot guarantee that it will be called from the main thread, you must ensure that the operation is performed asynchronously on the main thread.

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        let measurementFormatter = MeasurementFormatter()
        measurementFormatter.numberFormatter.minimumFractionDigits = 2
        measurementFormatter.numberFormatter.maximumFractionDigits = 2
        return measurementFormatter
    }()

    private func setTitleForDistanceMeasurements(direct: AGSDistance, horizontal: AGSDistance, vertical: AGSDistance) {
        DispatchQueue.main.async { [weak self] in
            guard let self = self else { return }
            if self.measurement.isVisible {
                self.navigationItem.title = String(
                    format: "Direct: %@ | Horizontal: %@ | Vertical: %@",
                    Self.measurementFormatter.string(from: Measurement(value: direct.value, unit: Unit(symbol: direct.unit.abbreviation))),
                    Self.measurementFormatter.string(from: Measurement(value: horizontal.value, unit: Unit(symbol: horizontal.unit.abbreviation))),
                    Self.measurementFormatter.string(from: Measurement(value: vertical.value, unit: Unit(symbol: vertical.unit.abbreviation)))
                )
            } else {
                self.navigationItem.title = "Long press and drag."
            }
        }
    }
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Create a distance measurement analysis

Use a AGSLocationDistanceMeasurement to perform and display a distance measurement analysis using 3D points to define the start and end locations.

Create a private lazy AGSLocationDistanceMeasurement named measurement. Upon launch, the distance measurement visualization should not be visible.

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        let point = AGSPointMake3D(0, 0, 0, 0, .wgs84())
        let measurement = AGSLocationDistanceMeasurement(startLocation: point, endLocation: point)
        measurement.measurementChangedHandler = setTitleForDistanceMeasurements
        measurement.isVisible = false
        measurement.unitSystem = .metric // .imperial
        return measurement
    }()

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Define a private method named setupAnalysisOverlay() to add the distance measurement analysis to the scene.

The distance measurement analysis is added to a scene view using an analysis overlay. An analysis overlay is a container for analyses. It can be used to display visual analyses in a scene view. You can add more than one analysis overlay and they are displayed on top of all other layers.

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        let point = AGSPointMake3D(0, 0, 0, 0, .wgs84())
        let measurement = AGSLocationDistanceMeasurement(startLocation: point, endLocation: point)
        measurement.measurementChangedHandler = setTitleForDistanceMeasurements
        measurement.isVisible = false
        measurement.unitSystem = .metric // .imperial
        return measurement
    }()

    private func setupAnalysisOverlay() {
        let analysisOverlay = AGSAnalysisOverlay()
        analysisOverlay.analyses.add(measurement)
        sceneView.analysisOverlays.add(analysisOverlay)
    }
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Define a private method named startDistanceMeasurement(point:) that receives a point as a parameter. This method is used to set the distance measurement analysis startLocation.

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        let analysisOverlay = AGSAnalysisOverlay()
        analysisOverlay.analyses.add(measurement)
        sceneView.analysisOverlays.add(analysisOverlay)
    }

    private func startDistanceMeasurement(point: AGSPoint) {
        measurement.isVisible = false
        measurement.startLocation = point
        measurement.endLocation = point
    }
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Define a private method named moveDistanceMeasurement(point:) that receives a point as a parameter. This method is used to set the distance measurement analysis endLocation and make it visible, if it's not visible already.

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        measurement.isVisible = false
        measurement.startLocation = point
        measurement.endLocation = point
    }

    private func moveDistanceMeasurement(point: AGSPoint) {
        measurement.endLocation = point
        if !measurement.isVisible {
            measurement.isVisible = true
        }
    }
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Define a private method named clearMeasurement(). This method is used to hide the distance measurement analysis.

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        measurement.endLocation = point
        if !measurement.isVisible {
            measurement.isVisible = true
        }
    }

    private func clearMeasurement() {
        measurement.isVisible = false
        navigationItem.title = "Long press and drag."
    }
Expand

Call clearMeasurement() when the user taps the "Clear" button.

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    func clearScene(_ sender: UIBarButtonItem) {

        clearMeasurement()

    }
Expand

In viewDidLoad(), call the method setupAnalysisOverlay().

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        super.viewDidLoad()
        setupScene()

        setupUI()

        setupAnalysisOverlay()

    }
Expand

Display the distance measurement analysis with touch events

Touch events determine where to perform and display the distance measurement analysis. A user can long-press and drag to reveal and move the distance measurement analysis' location around the screen.

Extend ViewController to conform to the AGSGeoViewTouchDelegate protocol and include the four long-press geoview touch delegate methods.

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Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.extension ViewController: AGSGeoViewTouchDelegate {

    func geoView(_ geoView: AGSGeoView, didLongPressAtScreenPoint screenPoint: CGPoint, mapPoint: AGSPoint) {

    }

    func geoView(_ geoView: AGSGeoView, didMoveLongPressToScreenPoint screenPoint: CGPoint, mapPoint: AGSPoint) {

    }

    func geoView(_ geoView: AGSGeoView, didEndLongPressAtScreenPoint screenPoint: CGPoint, mapPoint: AGSPoint) {

    }

    func geoViewDidCancelLongPress(_ geoView: AGSGeoView) {

    }

}

When the user begins a long-press touch event, call startDistanceMeasurement(point:).

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Add line.extension ViewController: AGSGeoViewTouchDelegate {

    func geoView(_ geoView: AGSGeoView, didLongPressAtScreenPoint screenPoint: CGPoint, mapPoint: AGSPoint) {

        startDistanceMeasurement(point: mapPoint)

    }

    func geoView(_ geoView: AGSGeoView, didMoveLongPressToScreenPoint screenPoint: CGPoint, mapPoint: AGSPoint) {

    }

    func geoView(_ geoView: AGSGeoView, didEndLongPressAtScreenPoint screenPoint: CGPoint, mapPoint: AGSPoint) {

    }

    func geoViewDidCancelLongPress(_ geoView: AGSGeoView) {

    }

}

When the user moves and ends a long-press touch event, call moveDistanceMeasurement(point:).

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Add line.Add line.extension ViewController: AGSGeoViewTouchDelegate {

    func geoView(_ geoView: AGSGeoView, didLongPressAtScreenPoint screenPoint: CGPoint, mapPoint: AGSPoint) {

        startDistanceMeasurement(point: mapPoint)

    }

    func geoView(_ geoView: AGSGeoView, didMoveLongPressToScreenPoint screenPoint: CGPoint, mapPoint: AGSPoint) {

        moveDistanceMeasurement(point: mapPoint)

    }

    func geoView(_ geoView: AGSGeoView, didEndLongPressAtScreenPoint screenPoint: CGPoint, mapPoint: AGSPoint) {

        moveDistanceMeasurement(point: mapPoint)

    }

    func geoViewDidCancelLongPress(_ geoView: AGSGeoView) {

    }

}

When the user cancels the long-press touch event, call clearMeasurement().

This may happen, for instance, when you have the magnifier visible and attempt to take a screenshot using the home/lock button combination.

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Add line.extension ViewController: AGSGeoViewTouchDelegate {

    func geoView(_ geoView: AGSGeoView, didLongPressAtScreenPoint screenPoint: CGPoint, mapPoint: AGSPoint) {

        startDistanceMeasurement(point: mapPoint)

    }

    func geoView(_ geoView: AGSGeoView, didMoveLongPressToScreenPoint screenPoint: CGPoint, mapPoint: AGSPoint) {

        moveDistanceMeasurement(point: mapPoint)

    }

    func geoView(_ geoView: AGSGeoView, didEndLongPressAtScreenPoint screenPoint: CGPoint, mapPoint: AGSPoint) {

        moveDistanceMeasurement(point: mapPoint)

    }

    func geoViewDidCancelLongPress(_ geoView: AGSGeoView) {

        clearMeasurement()

    }

}

In the setupScene() method, assign ViewController to sceneView.touchDelegate.

This step connects the sceneView user touch interactions with ViewController via the AGSGeoViewTouchDelegate protocol.

ViewController.swift
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Add line.    private func setupScene() {
        let scene: AGSScene = {
            let portal = AGSPortal.arcGISOnline(withLoginRequired: false)

            let item = AGSPortalItem(portal: portal, itemID: "7558ee942b2547019f66885c44d4f0b1")

            return AGSScene(item: item)
        }()
        sceneView.scene = scene

        sceneView.touchDelegate = self

    }
Expand

Run the app

Press Command + R to run the app.

If you are using the Xcode simulator your system must meet these minimum requirements: macOS Big Sur 11.3, Xcode 13, iOS 13. If you are using a physical device, then refer to the system requirements.

You should see a scene of hotspots in the Yosemite Valley. Long-press and drag to display and move a distance measurement analysis to evaluate the horizontal, vertical, and direct distances between two park locations.

What's next?

Learn how to use additional API features, ArcGIS location services, and ArcGIS tools in these tutorials: