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
#include "ViewshedGeoElement.h"
#include "ArcGISTiledElevationSource.h"
#include "Scene.h"
#include "SceneQuickView.h"
#include "Point.h"
#include "ArcGISSceneLayer.h"
#include "SimpleRenderer.h"
#include "ModelSceneSymbol.h"
#include "GeoElementViewshed.h"
#include "GeometryEngine.h"
#include "OrbitGeoElementCameraController.h"
#include "MapTypes.h"
#include "Surface.h"
#include "ElevationSourceListModel.h"
#include "LayerListModel.h"
#include "AnalysisOverlay.h"
#include "AnalysisOverlayListModel.h"
#include "AnalysisListModel.h"
#include "GraphicsOverlayListModel.h"
#include "LayerSceneProperties.h"
#include "SceneViewTypes.h"
#include "RendererSceneProperties.h"
#include "SymbolTypes.h"
#include "GraphicListModel.h"
#include "GeodeticDistanceResult.h"
#include "LinearUnit.h"
#include "AngularUnit.h"
#include "AttributeListModel.h"
#include "Graphic.h"
#include "GraphicsOverlay.h"
#include "SpatialReference.h"
#include <QTimer>
#include <QString>
#include <QUrl>
#include <QVariant>
#include <QList>
#include <QtCore/qglobal.h>
#include <QStandardPaths>
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();
}
}