Distance measurement analysis

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Measure distances between two points in 3D.

Image of distance measurement analysis

Use case

The distance measurement analysis allows you to add to your app the same interactive measuring experience found in ArcGIS Pro, City Engine, and the ArcGIS API for JavaScript. You can set the unit system of measurement (metric or imperial). The units automatically switch to one appropriate for the current scale.

How to use the sample

Choose a unit system for the measurement. Tap any location in the scene to start measuring. Move the mouse to an end location, and tap to complete the measurement. Tap a new location to clear and start a new measurement.

How it works

  1. Create an AnalysisOverlay object and add it to the analysis overlay collection of the SceneView object.
  2. Specify the start location and end location to create a LocationDistanceMeasurement object. Initially, the start and end locations can be the same point.
  3. Add the location distance measurement analysis to the analysis overlay.
  4. The MeasurementChanged event will be raised if the distances change. You can get the new values for the DirectDistance, HorizontalDistance, and VerticalDistance from the event arguments.

Relevant API

  • AnalysisOverlay
  • LocationDistanceMeasurement
  • LocationDistanceMeasurement.MeasurementChanged

Additional information

The LocationDistanceMeasurement analysis only performs planar distance calculations. This may not be appropriate for large distances where the Earth's curvature must be considered.

Tags

3D, analysis, distance, measure

Sample Code

DistanceMeasurement.cs
                                                                                                                                                                                                                                        
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// Copyright 2021 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;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.UI.Controls;
using Esri.ArcGISRuntime.UI.GeoAnalysis;
using Foundation;
using System;
using System.Diagnostics;
using UIKit;

namespace ArcGISRuntime.Samples.DistanceMeasurement
{
    [Register("DistanceMeasurement")]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        name: "Distance measurement analysis",
        category: "Analysis",
        description: "Measure distances between two points in 3D.",
        instructions: "Choose a unit system for the measurement. Tap any location in the scene to start measuring. Move the mouse to an end location, and tap to complete the measurement. Tap a new location to clear and start a new measurement.",
        tags: new[] { "3D", "analysis", "distance", "measure" })]
    public class DistanceMeasurement : UIViewController
    {
        // Hold references to UI controls.
        private SceneView _mySceneView;
        private UILabel _resultLabel;
        private UIBarButtonItem _helpButton;
        private UIBarButtonItem _changeUnitsButton;

        // URLs to various services used to provide an interesting scene for the sample.
        private readonly Uri _buildingService = new Uri("https://tiles.arcgis.com/tiles/P3ePLMYs2RVChkJx/arcgis/rest/services/Buildings_Brest/SceneServer/layers/0");
        private readonly Uri _worldElevationService = new Uri("https://elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/Terrain3D/ImageServer");

        // Reference to the measurement.
        private LocationDistanceMeasurement _distanceMeasurement;

        public DistanceMeasurement()
        {
            Title = "Distance measurement analysis";
        }

        private void Initialize()
        {
            // Create a scene with elevation.
            Surface sceneSurface = new Surface();
            sceneSurface.ElevationSources.Add(new ArcGISTiledElevationSource(_worldElevationService));
            Scene myScene = new Scene(Basemap.CreateTopographic())
            {
                BaseSurface = sceneSurface
            };

            // Create and add a building layer.
            ArcGISSceneLayer buildingsLayer = new ArcGISSceneLayer(_buildingService);
            myScene.OperationalLayers.Add(buildingsLayer);

            // Create and add an analysis overlay.
            AnalysisOverlay measureAnalysisOverlay = new AnalysisOverlay();
            _mySceneView.AnalysisOverlays.Add(measureAnalysisOverlay);

            // Create an initial distance measurement and show it.
            MapPoint start = new MapPoint(-4.494677, 48.384472, 24.772694, SpatialReferences.Wgs84);
            MapPoint end = new MapPoint(-4.495646, 48.384377, 58.501115, SpatialReferences.Wgs84);
            _distanceMeasurement = new LocationDistanceMeasurement(start, end);
            measureAnalysisOverlay.Analyses.Add(_distanceMeasurement);

            // Keep the UI updated.
            _distanceMeasurement.MeasurementChanged += MeasurementChanged;

            // Show the scene in the view.
            _mySceneView.Scene = myScene;
            _mySceneView.SetViewpointCamera(new Camera(start, 200, 45, 45, 0));
        }

        private void MeasurementChanged(object sender, EventArgs e)
        {
            // This is needed because measurement change events occur on a non-UI thread and this code accesses UI object.
            BeginInvokeOnMainThread(() =>
            {
                // Update the labels with new values in the format {value} {unit system}.
                string direct = $"{_distanceMeasurement.DirectDistance.Value:F} {_distanceMeasurement.DirectDistance.Unit.Abbreviation}";
                string vertical = $"{_distanceMeasurement.VerticalDistance.Value:F} {_distanceMeasurement.VerticalDistance.Unit.Abbreviation}";
                string horizontal = $"{_distanceMeasurement.HorizontalDistance.Value:F} {_distanceMeasurement.HorizontalDistance.Unit.Abbreviation}";
                _resultLabel.Text = $"Direct: {direct}, V: {vertical}, H: {horizontal}";
            });
        }

        private async void MySceneView_GeoViewTapped(object sender, GeoViewInputEventArgs e)
        {
            try
            {
                // Get the geographic location for the current mouse position.
                MapPoint geoPoint = await _mySceneView.ScreenToLocationAsync(e.Position);

                if (geoPoint == null) return;

                // Update the location distance measurement.
                _distanceMeasurement.EndLocation = geoPoint;
            }
            catch (Exception ex)
            {
                Debug.WriteLine(ex.ToString());
            }
        }

        private void UnitChangeButton_TouchUpInside(object sender, EventArgs e)
        {
            // Create the view controller that will present the list of unit systems.
            UIAlertController unitSystemSelectionAlert =
                UIAlertController.Create(null, "Change unit system", UIAlertControllerStyle.ActionSheet);

            // Needed to prevent a crash on iPad.
            UIPopoverPresentationController
                presentationPopover = unitSystemSelectionAlert.PopoverPresentationController;
            if (presentationPopover != null)
            {
                presentationPopover.BarButtonItem = (UIBarButtonItem)sender;
                presentationPopover.PermittedArrowDirections = UIPopoverArrowDirection.Down;
            }

            // Show an option for each unit system.
            foreach (UnitSystem system in Enum.GetValues(typeof(UnitSystem)))
            {
                // Upon selecting a unit system, update the distance measure.
                unitSystemSelectionAlert.AddAction(UIAlertAction.Create(system.ToString(), UIAlertActionStyle.Default,
                    action => _distanceMeasurement.UnitSystem = system));
            }

            // Show the alert.
            PresentViewController(unitSystemSelectionAlert, true, null);
        }

        private void ShowHelp_Click(object sender, EventArgs e)
        {
            // Prompt for the type of convex hull to create.
            UIAlertController unionAlert = UIAlertController.Create("Tap to update", "Tap in the scene to set a new end point for the distance measurement.", UIAlertControllerStyle.Alert);
            unionAlert.AddAction(UIAlertAction.Create("Ok", UIAlertActionStyle.Default, null));

            // Show the alert.
            PresentViewController(unionAlert, true, null);
        }

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

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

            _mySceneView = new SceneView();
            _mySceneView.TranslatesAutoresizingMaskIntoConstraints = false;

            UIToolbar toolbar = new UIToolbar();
            toolbar.TranslatesAutoresizingMaskIntoConstraints = false;

            _resultLabel = new UILabel
            {
                Text = "Tap to measure distance.",
                BackgroundColor = UIColor.FromWhiteAlpha(0f, .6f),
                TextColor = UIColor.White,
                TextAlignment = UITextAlignment.Center,
                TranslatesAutoresizingMaskIntoConstraints = false
            };

            _helpButton = new UIBarButtonItem();
            _helpButton.Title = "Help";

            _changeUnitsButton = new UIBarButtonItem();
            _changeUnitsButton.Title = "Change units";

            toolbar.Items = new[]
            {
                _changeUnitsButton,
                new UIBarButtonItem(UIBarButtonSystemItem.FlexibleSpace),
                _helpButton
            };

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

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

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

                _resultLabel.TopAnchor.ConstraintEqualTo(View.SafeAreaLayoutGuide.TopAnchor),
                _resultLabel.TrailingAnchor.ConstraintEqualTo(View.TrailingAnchor),
                _resultLabel.LeadingAnchor.ConstraintEqualTo(View.LeadingAnchor),
                _resultLabel.HeightAnchor.ConstraintEqualTo(40)
            });
        }

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

            // Subscribe to events.
            _mySceneView.GeoViewTapped += MySceneView_GeoViewTapped;
            _helpButton.Clicked += ShowHelp_Click;
            _changeUnitsButton.Clicked += UnitChangeButton_TouchUpInside;
            if (_distanceMeasurement != null) _distanceMeasurement.MeasurementChanged += MeasurementChanged;
        }

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

            // Unsubscribe from events, per best practice.
            _mySceneView.GeoViewTapped -= MySceneView_GeoViewTapped;
            _helpButton.Clicked -= ShowHelp_Click;
            _changeUnitsButton.Clicked -= UnitChangeButton_TouchUpInside;
            if (_distanceMeasurement != null) _distanceMeasurement.MeasurementChanged -= MeasurementChanged;
        }
    }
}

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