Analyze the viewshed for an object (GeoElement) in a scene.
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
SimpleRendererwhich has a heading expression set in theGraphicsOverlay. This way you can relate the viewshed's heading to theGeoElementobject's heading.
- Use a
- Create a
GeoElementViewshedwith configuration for the viewshed analysis. - Add the viewshed to an
AnalysisOverlayand add the overlay to the scene. - Configure the SceneView
CameraControllerto 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.
| Link | Local Location |
|---|---|
| Model Marker Symbol Data | <userhome>/ArcGIS/Runtime/Data/3D/bradley_low_3ds/bradle.3ds |
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.
Tags
3D, analysis, buildings, model, scene, viewshed, visibility analysis
Sample Code
// [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] #ifdef PCH_BUILD #include "pch.hpp" #endif // PCH_BUILD // sample headers #include "ViewshedGeoElement.h" // ArcGIS Maps SDK headers #include "AnalysisListModel.h" #include "AnalysisOverlay.h" #include "AnalysisOverlayListModel.h" #include "AngularUnit.h" #include "ArcGISSceneLayer.h" #include "ArcGISTiledElevationSource.h" #include "AttributeListModel.h" #include "ElevationSourceListModel.h" #include "GeoElementViewshed.h" #include "GeodeticDistanceResult.h" #include "GeometryEngine.h" #include "Graphic.h" #include "GraphicListModel.h" #include "GraphicsOverlay.h" #include "GraphicsOverlayListModel.h" #include "LayerListModel.h" #include "LayerSceneProperties.h" #include "LinearUnit.h" #include "MapTypes.h" #include "ModelSceneSymbol.h" #include "OrbitGeoElementCameraController.h" #include "Point.h" #include "RendererSceneProperties.h" #include "Scene.h" #include "SceneQuickView.h" #include "SceneViewTypes.h" #include "SimpleRenderer.h" #include "SpatialReference.h" #include "Surface.h" #include "SymbolTypes.h" // Qt headers #include <QList> #include <QStandardPaths> #include <QString> #include <QTimer> #include <QUrl> #include <QVariant> #include <QtCore/qglobal.h> using namespace Esri::ArcGISRuntime; // helper method to get cross platform data path namespace { QString defaultDataPath() { QString dataPath; #ifdef Q_OS_IOS dataPath = QStandardPaths::writableLocation(QStandardPaths::DocumentsLocation); #else dataPath = QStandardPaths::writableLocation(QStandardPaths::HomeLocation); #endif return dataPath; } } // namespace ViewshedGeoElement::ViewshedGeoElement(QQuickItem* parent /* = nullptr */): QQuickItem(parent) { } void ViewshedGeoElement::init() { // Register classes for QML qmlRegisterType<SceneQuickView>("Esri.Samples", 1, 0, "SceneView"); qmlRegisterType<ViewshedGeoElement>("Esri.Samples", 1, 0, "ViewshedGeoElementSample"); } void ViewshedGeoElement::componentComplete() { QQuickItem::componentComplete(); // Create a scene and give it to the SceneView m_sceneView = findChild<SceneQuickView*>("sceneView"); Scene* scene = new Scene(BasemapStyle::ArcGISImageryStandard, this); // Create a surface Surface* surface = new Surface(this); surface->elevationSources()->append( new ArcGISTiledElevationSource( QUrl("https://elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/Terrain3D/ImageServer"), this)); scene->setBaseSurface(surface); // Add a SceneLayer ArcGISSceneLayer* sceneLayer = new ArcGISSceneLayer(QUrl("https://tiles.arcgis.com/tiles/P3ePLMYs2RVChkJx/arcgis/rest/services/Buildings_Brest/SceneServer/layers/0"), this); scene->operationalLayers()->append(sceneLayer); // Add an AnalysisOverlay m_analysisOverlay = new AnalysisOverlay(this); m_sceneView->analysisOverlays()->append(m_analysisOverlay); // Add a GraphicsOverlay createGraphicsOverlay(); // Create a Graphic createGraphic(); // Create the GeoElementViewshed const double horizontalAngle = 90.0; const double verticalAngle = 25.0; const double minDistance = 5.0; const double maxDistance = 250.0; const double headingOffset = 0.0; const double pitchOffset = 0.0; m_viewshed = new GeoElementViewshed(m_tank, horizontalAngle, verticalAngle, minDistance, maxDistance, headingOffset, pitchOffset, this); m_viewshed->setOffsetY(0.5); m_viewshed->setOffsetZ(0.5); m_analysisOverlay->analyses()->append(m_viewshed); // Add the Scene to the SceneView m_sceneView->setArcGISScene(scene); // create the camera controller to follow the graphic OrbitGeoElementCameraController* followingController = new OrbitGeoElementCameraController(m_tank, 200.0, this); followingController->setCameraPitchOffset(45.0); m_sceneView->setCameraController(followingController); // Create a Timer m_timer = new QTimer(this); m_timer->setInterval(100); connect(m_timer, &QTimer::timeout, this, &ViewshedGeoElement::animate); // connect to the mouse clicked signal connect(m_sceneView, &SceneQuickView::mouseClicked, this, [this](QMouseEvent& event) { m_waypoint = m_sceneView->screenToBaseSurface(event.position().x(), event.position().y()); m_timer->start(); }); } void ViewshedGeoElement::createGraphicsOverlay() { // Add a GraphicsOverlay m_graphicsOverlay = new GraphicsOverlay(this); m_sceneView->graphicsOverlays()->append(m_graphicsOverlay); // Set the SurfacePlacement LayerSceneProperties sceneProperties = m_graphicsOverlay->sceneProperties(); sceneProperties.setSurfacePlacement(SurfacePlacement::Relative); m_graphicsOverlay->setSceneProperties(sceneProperties); // Set a Renderer SimpleRenderer* simpleRenderer = new SimpleRenderer(this); const QString headingExpression = QString("[%1]").arg(m_headingAttr); simpleRenderer->setSceneProperties(RendererSceneProperties(headingExpression, "", "")); m_graphicsOverlay->setRenderer(simpleRenderer); } void ViewshedGeoElement::createGraphic() { // Create the Graphic Point const double x = -4.508708007847015; const double y = 48.38823243446344; const double z = 0; const Point tankPoint(x, y, z, SpatialReference(4326)); const float scale = 10; // Create the Graphic Symbol ModelSceneSymbol* sceneSymbol = new ModelSceneSymbol(QUrl(defaultDataPath() + "/ArcGIS/Runtime/Data/3D/bradley_low_3ds/bradle.3ds"), scale, this); sceneSymbol->setAnchorPosition(SceneSymbolAnchorPosition::Bottom); sceneSymbol->setHeading(90.0f); // Create the Graphic QVariantMap attr; attr[m_headingAttr] = 150.0; m_tank = new Graphic(tankPoint, attr, sceneSymbol, this); m_graphicsOverlay->graphics()->append(m_tank); } void ViewshedGeoElement::animate() { if (m_waypoint.isEmpty()) return; // get current location and distance from waypoint Point location = geometry_cast<Point>(m_tank->geometry()); const GeodeticDistanceResult distance = GeometryEngine::distanceGeodetic(location, m_waypoint, LinearUnit(m_linearUnit), AngularUnit(m_angularUnit), m_curveType); // move toward waypoint based on speed and update orientation location = GeometryEngine::moveGeodetic(QList<Point>{location}, 1.0, LinearUnit(m_linearUnit), distance.azimuth1(), AngularUnit(m_angularUnit), m_curveType).at(0); m_tank->setGeometry(location); // update the heading const double heading = m_tank->attributes()->attributeValue(m_headingAttr).toDouble(); const QString newHeading = QString::number(heading + (distance.azimuth1() - heading) / 10); m_tank->attributes()->replaceAttribute(m_headingAttr, newHeading); // reached waypoint if (distance.distance() <= 5) { m_waypoint = Point(); m_timer->stop(); } }