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This sample demonstrates how to calculate a Viewshed from a GeoElement.
Use case
A viewshed analysis is a type of visual analysis you can perform on a scene. The viewshed aims to answer the question 'What can I see from a given location?'. The output is an overlay with two different colors - one representing the visible areas (green) and the other representing the obstructed areas (red).
How to use the sample
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.
How it works
Create and show the scene, with an elevation source and a buildings layer.
Add a model (the GeoElement
) to represent the observer (in this case, a tank).
Use a SimpleRenderer
which has a heading expression set in the GraphicsOverlay
. This way you can relate the viewshed's heading to the GeoElement
object's heading.
Create a GeoElementViewshed
with configuration for the viewshed analysis.
Add the viewshed to an AnalysisOverlay
and add the overlay to the scene.
Configure the SceneView CameraController
to orbit the vehicle.
Relevant API
AnalysisOverlay
GeodeticDistanceResult
GeoElementViewshed
GeometryEngine.distanceGeodetic (used to animate the vehicle)
ModelSceneSymbol
OrbitGeoElementCameraController
Offline data
Offline sample data will be downloaded by the sample viewer automatically.
About the data
This sample shows a Buildings in Brest, France Scene from ArcGIS Online. The sample uses a Tank model scene symbol hosted as an item on ArcGIS Online.
3D, analysis, buildings, model, scene, viewshed, visibility analysis
Sample CodeViewshedGeoElement.qml
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// [WriteFile Name=ViewshedGeoElement, Category=Analysis]
// [Legal]
// 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.
// [Legal]
import QtQuick
import Esri.ArcGISRuntime
import Esri.ArcGISExtras
Rectangle {
id: rootRectangle
clip : true
width : 800
height : 600
readonly property string dataPath : {
Qt.platform.os === "ios" ?
System.writableLocation(System.StandardPathsDocumentsLocation) + "/ArcGIS/Runtime/Data" :
System.writableLocation(System.StandardPathsHomeLocation) + "/ArcGIS/Runtime/Data"
}
readonly property string headingAttr : "HEADING"
readonly property LinearUnit linearUnit : LinearUnit {
linearUnitId : Enums.LinearUnitIdMeters
}
readonly property AngularUnit angularUnit : AngularUnit {
angularUnitId : Enums.AngularUnitIdDegrees
}
readonly property var geodeticCurveType : Enums.GeodeticCurveTypeGeodesic
property Point waypoint : null
SceneView {
id: sceneView
anchors.fill : parent
Component.onCompleted : {
// Set the focus on SceneView to initially enable keyboard navigation
forceActiveFocus();
}
Scene {
id: scene
Basemap {
initStyle : Enums.BasemapStyleArcGISImageryStandard
}
// Set the Scene's Surface
Surface {
ArcGISTiledElevationSource {
url : "https://elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/Terrain3D/ImageServer"
}
}
// Add a Scene Layer
ArcGISSceneLayer {
url : "https://tiles.arcgis.com/tiles/P3ePLMYs2RVChkJx/arcgis/rest/services/Buildings_Brest/SceneServer/layers/0"
}
onLoadStatusChanged : {
if (loadStatus !== Enums.LoadStatusLoaded)
return ;
// Set the Camera Controller
const controller = ArcGISRuntimeEnvironment.createObject( "OrbitGeoElementCameraController" , {
targetGeoElement : tank, cameraDistance : 200 ,
cameraPitchOffset : 45
});
sceneView.cameraController = controller;
}
}
// Declare a GraphicsOverlay
GraphicsOverlay {
SimpleRenderer {
// set up heading expression for the tank
RendererSceneProperties {
headingExpression : "[%1]" .arg(headingAttr)
}
}
LayerSceneProperties {
surfacePlacement : Enums.SurfacePlacementRelative
}
// Create the Tank Graphic
Graphic {
id: tank
Point {
x : -4.508708007847015
y : 48.38823243446344
z : 0
spatialReference : Factory.SpatialReference.createWgs84()
}
ModelSceneSymbol {
id: sceneSymbol
url : dataPath + "/3D/bradley_low_3ds/bradle.3ds"
anchorPosition : Enums.SceneSymbolAnchorPositionBottom
scale : 10
heading : 90.0
}
Component.onCompleted : {
tank.attributes.insertAttribute(headingAttr, 150.0 )
}
}
}
// Declare an Analysis Overlay
AnalysisOverlay {
id: analysisOverlay
// Create the Location Viewshed
GeoElementViewshed {
id: geoelementViewshed
horizontalAngle : 90.0
verticalAngle : 25.0
minDistance : 5.0
maxDistance : 250.0
headingOffset : 0
pitchOffset : 0
offsetY : 0.5
offsetZ : 0.5
geoElement : tank
}
}
onMouseClicked : mouse => {
waypoint = sceneView.screenToBaseSurface(mouse.x, mouse.y);
timer.start();
}
}
function animate ( ) {
if (waypoint === null )
return ;
// get current location and distance from waypoint
let location = tank.geometry;
const distance = GeometryEngine.distanceGeodetic(location, waypoint, linearUnit, angularUnit, geodeticCurveType);
// move toward waypoint based on speed and update orientation
location = GeometryEngine.moveGeodetic([location], 1.0 , linearUnit, distance.azimuth1, angularUnit, geodeticCurveType);
tank.geometry = location[ 0 ];
// update the heading
const heading = tank.attributes.attributeValue(headingAttr);
tank.attributes.replaceAttribute(headingAttr, heading + (distance.azimuth1 - heading) / 10 );
// reached waypoint
if (distance.distance <= 5 ) {
waypoint = null ;
timer.stop();
}
}
Timer {
id: timer
interval : 100
repeat : true
onTriggered : animate()
}
}