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Unit Class

Defines a base class for units of measurement.
Inheritance Hierarchy

Namespace:  Esri.ArcGISRuntime.Geometry
Assembly:  Esri.ArcGISRuntime (in Esri.ArcGISRuntime.dll) Version: 100.9.0
Syntax
public abstract class Unit

The Unit type exposes the following members.

Properties
  NameDescription
Public propertyCode exampleAbbreviation
Gets the abbreviation of the unit.
Public propertyDisplayName
Gets the display name of the unit.
Public propertyName
Gets the name of the unit.
Public propertyCode examplePluralDisplayName
Retrieve the plural display name of the unit.
Public propertyUnitId
Gets the well-known ID of the unit.
Public propertyUnitType
Returns the type of unit.
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Methods
  NameDescription
Public methodStatic memberCode exampleFromUnitId
Creates a unit based on a unit ID
Public methodIsEqual
Returns true of the Unit instances are the same.
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Remarks

The unit abstract class provides a common base class between all units (linear, area, and angular) for different types of measurement used throughout ArcGIS Runtime. Projected coordinate systems define coordinates using linear measurements, for example using meters or miles, which are represented by LinearUnit. Linear units are also used to return distance measurements, for example by some members of GeometryEngine. Geographic coordinate systems define coordinates using angular measurements, for example using degrees or radians, which are represented by AngularUnit. Methods that calculate the size of areas, for example in acres or square kilometers, use area units. These are represented by AreaUnit. Linear, angular, and area units can be defined by using enumerations of the most common units of measurement. They can also be defined by Well-Known ID (WKID) or Well-Known Text (WKText).

Custom Unit implementations are not supported by ArcGIS Runtime.

Examples

WPF

Example Name: ViewshedGeoElement

Analyze the viewshed for an object (GeoElement) in a scene.

Code example screen shot.

C#
// 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 ArcGISRuntime.Samples.Managers;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.UI;
using Esri.ArcGISRuntime.UI.GeoAnalysis;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Timers;
using System.Windows;

namespace ArcGISRuntime.WPF.Samples.ViewshedGeoElement
{
    [ArcGISRuntime.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" })]
    [ArcGISRuntime.Samples.Shared.Attributes.OfflineData("07d62a792ab6496d9b772a24efea45d0")]
    public partial class ViewshedGeoElement
    {
        // 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.FromUnitId(9001);
        private readonly AngularUnit _degreesUnit = (AngularUnit)Unit.FromUnitId(9102);

        public ViewshedGeoElement()
        {
            InitializeComponent();
            Initialize();
        }

        private async void Initialize()
        {
            // Create the scene with an imagery basemap.
            MySceneView.Scene = new Scene(Basemap.CreateImagery());

            // 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);

            // 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.
                Timer animationTimer = new Timer(60)
                {
                    Enabled = true,
                    AutoReset = true
                };
                // - Move the tank every time the timer expires.
                animationTimer.Elapsed += (o, e) =>
                {
                    AnimateTank();
                };
                // - Start the timer.
                animationTimer.Start();

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

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

            // Get the current location and distance from the destination.
            MapPoint location = (MapPoint)_tank.Geometry;
            GeodeticDistanceResult distance = GeometryEngine.DistanceGeodetic(
                location, _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");
        }
    }
}
XAML
<UserControl x:Class="ArcGISRuntime.WPF.Samples.ViewshedGeoElement.ViewshedGeoElement"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:esri="http://schemas.esri.com/arcgis/runtime/2013">
    <Grid>
        <esri:SceneView x:Name="MySceneView" />
        <Border Style="{StaticResource BorderStyle}">
            <TextBlock Text="Tap to set a destination for the vehicle."
                       TextAlignment="Center"
                       FontWeight="SemiBold" />
        </Border>
    </Grid>
</UserControl>
See Also
Additional Examples
Hyperlink to ExampleDescription
ViewshedGeoElementAnalyze the viewshed for an object (GeoElement) in a scene.