Viewshed for GeoElement

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
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
// Copyright 2022 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 ArcGIS.Samples.Managers;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.UI;
using Esri.ArcGISRuntime.UI.GeoAnalysis;

namespace ArcGIS.Samples.ViewshedGeoElement
{
    [ArcGIS.Samples.Shared.Attributes.Sample(
        name: "Viewshed for GeoElement",
        category: "Analysis",
        description: "Analyze the viewshed for an object (GeoElement) in a scene.",
        instructions: "Tap to set a destination for the vehicle (a GeoElement). The vehicle will 'drive' towards the tapped location. The viewshed analysis will update as the vehicle moves.",
        tags: new[] { "3D", "analysis", "buildings", "model", "scene", "viewshed", "visibility analysis" })]
    [ArcGIS.Samples.Shared.Attributes.OfflineData("07d62a792ab6496d9b772a24efea45d0")]
    public partial class ViewshedGeoElement : ContentPage
    {
        // URLs to the scene layer with buildings and the elevation source
        private readonly Uri _elevationUri = new Uri("https://elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/Terrain3D/ImageServer");
        private readonly Uri _buildingsUri = new Uri("https://tiles.arcgis.com/tiles/P3ePLMYs2RVChkJx/arcgis/rest/services/Building_Johannesburg/SceneServer");

        // Graphic and overlay for showing the tank
        private readonly GraphicsOverlay _tankOverlay = new GraphicsOverlay();
        private Graphic _tank;

        // Animation properties
        private MapPoint _tankEndPoint;

        // Units for geodetic calculation (used in animating tank)
        private readonly LinearUnit _metersUnit = (LinearUnit)Unit.FromWkid(9001);
        private readonly AngularUnit _degreesUnit = (AngularUnit)Unit.FromWkid(9102);

        public ViewshedGeoElement()
        {
            InitializeComponent();

            // Create the UI, setup the control references and execute initialization.
            _ = Initialize();
        }

        private async Task Initialize()
        {
            // Create the scene with an imagery basemap.
            MySceneView.Scene = new Scene(BasemapStyle.ArcGISImageryStandard);

            // Add the elevation surface.
            ArcGISTiledElevationSource tiledElevationSource = new ArcGISTiledElevationSource(_elevationUri);
            Surface baseSurface = new Surface
            {
                ElevationSources = { tiledElevationSource }
            };
            MySceneView.Scene.BaseSurface = baseSurface;

            // Add buildings.
            ArcGISSceneLayer sceneLayer = new ArcGISSceneLayer(_buildingsUri);
            MySceneView.Scene.OperationalLayers.Add(sceneLayer);
            await sceneLayer.LoadAsync();

            // Configure the graphics overlay for the tank and add the overlay to the SceneView.
            _tankOverlay.SceneProperties.SurfacePlacement = SurfacePlacement.Relative;
            MySceneView.GraphicsOverlays.Add(_tankOverlay);

            // Configure the heading expression for the tank; this will allow the
            //     viewshed to update automatically based on the tank's position.
            SimpleRenderer renderer3D = new SimpleRenderer();
            renderer3D.SceneProperties.HeadingExpression = "[HEADING]";
            _tankOverlay.Renderer = renderer3D;

            try
            {
                // Create the tank graphic - get the model path.
                string modelPath = GetModelPath();
                // - Create the symbol and make it 10x larger (to be the right size relative to the scene).
                ModelSceneSymbol tankSymbol = await ModelSceneSymbol.CreateAsync(new Uri(modelPath), 10);
                // - Adjust the position.
                tankSymbol.Heading = 90;
                // - The tank will be positioned relative to the scene surface by its bottom.
                //     This ensures that the tank is on the ground rather than partially under it.
                tankSymbol.AnchorPosition = SceneSymbolAnchorPosition.Bottom;
                // - Create the graphic.
                _tank = new Graphic(new MapPoint(28.047199, -26.189105, SpatialReferences.Wgs84), tankSymbol);
                // - Update the heading.
                _tank.Attributes["HEADING"] = 0.0;
                // - Add the graphic to the overlay.
                _tankOverlay.Graphics.Add(_tank);

                // Create a viewshed for the tank.
                GeoElementViewshed geoViewshed = new GeoElementViewshed(
                    geoElement: _tank,
                    horizontalAngle: 90.0,
                    verticalAngle: 40.0,
                    minDistance: 0.1,
                    maxDistance: 250.0,
                    headingOffset: 0.0,
                    pitchOffset: 0.0)
                {
                    // Offset viewshed observer location to top of tank.
                    OffsetZ = 3.0
                };

                // Create the analysis overlay and add to the scene.
                AnalysisOverlay overlay = new AnalysisOverlay();
                overlay.Analyses.Add(geoViewshed);
                MySceneView.AnalysisOverlays.Add(overlay);

                // Create a camera controller to orbit the tank.
                OrbitGeoElementCameraController cameraController = new OrbitGeoElementCameraController(_tank, 200.0)
                {
                    CameraPitchOffset = 45.0
                };
                // - Apply the camera controller to the SceneView.
                MySceneView.CameraController = cameraController;

                // Create a timer; this will enable animating the tank.
                Dispatcher.StartTimer(new TimeSpan(0, 0, 0, 0, 60), () =>
                {
                    // Move the tank every time the timer elapses.
                    AnimateTank();
                    // Keep the timer running.
                    return true;
                });

                // Allow the user to click to define a new destination.
                MySceneView.GeoViewTapped += (sender, args) => { _tankEndPoint = args.Location; };
            }
            catch (Exception e)
            {
                await Application.Current.MainPage.DisplayAlert("Error", e.ToString(), "OK");
            }
        }

        private void AnimateTank()
        {
            // Return if tank already arrived.
            if (_tankEndPoint == null)
            {
                return;
            }

            // Get current location and distance from the destination.
            MapPoint location = (MapPoint)_tank.Geometry;
            GeodeticDistanceResult distance = location.DistanceGeodetic(_tankEndPoint, _metersUnit, _degreesUnit,
                GeodeticCurveType.Geodesic);

            // Move the tank a short distance.
            location = GeometryEngine.MoveGeodetic(new List<MapPoint>() { location }, 1.0, _metersUnit, distance.Azimuth1, _degreesUnit,
                GeodeticCurveType.Geodesic).First();
            _tank.Geometry = location;

            // Rotate to face the destination.
            double heading = (double)_tank.Attributes["HEADING"];
            heading = heading + (distance.Azimuth1 - heading) / 10;
            _tank.Attributes["HEADING"] = heading;

            // Clear the destination if the tank already arrived.
            if (distance.Distance < 5)
            {
                _tankEndPoint = null;
            }
        }

        private static string GetModelPath()
        {
            // Returns the tank model.

            return DataManager.GetDataFolder("07d62a792ab6496d9b772a24efea45d0", "bradle.3ds");
        }
    }
}