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

Use case

An exploratory viewshed analysis is a type of visual analysis you can perform at the current rendered resolution of a scene. The exploratory 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).

Note: This analysis is a form of “exploratory analysis”, which means the results are calculated on the current scale of the data, and the results are generated very quickly but not persisted. If persisted analysis performed at the full resolution of the data is required, consider using a ViewshedFunction to perform a viewshed calculation instead.

How to use the sample

Tap to set a destination for the vehicle (a GeoElement). The vehicle will ‘drive’ towards the tapped location. The exploratory viewshed analysis will update as the vehicle moves.

How it works

  1. Create and show the scene, with an elevation source and a buildings layer.
  2. 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.
  3. Create an ExploratoryGeoElementViewshed with configuration for the viewshed analysis.
  4. Add the viewshed to an AnalysisOverlay and add the overlay to the scene.
  5. Configure the SceneView CameraController to orbit the vehicle.

Relevant API

  • AnalysisOverlay
  • ExploratoryGeoElementViewshed
  • GeodeticDistanceResult
  • GeometryEngine::distanceGeodetic (used to animate the vehicle)
  • ModelSceneSymbol
  • OrbitGeoElementCameraController

Offline data

Offline sample data will be downloaded by the sample viewer automatically.

LinkLocal 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, exploratory viewshed, model, scene, visibility analysis

Sample Code

ShowExploratoryViewshedFromGeoElementInScene.cpp ShowExploratoryViewshedFromGeoElementInScene.cpp ShowExploratoryViewshedFromGeoElementInScene.h ShowExploratoryViewshedFromGeoElementInScene.qml main.cpp
// [WriteFile Name=ShowExploratoryViewshedFromGeoElementInScene, 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 "ShowExploratoryViewshedFromGeoElementInScene.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 "ExploratoryGeoElementViewshed.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
ShowExploratoryViewshedFromGeoElementInScene::ShowExploratoryViewshedFromGeoElementInScene(QQuickItem* parent /* = nullptr */) :
QQuickItem(parent)
{
}
void ShowExploratoryViewshedFromGeoElementInScene::init()
{
// Register classes for QML
qmlRegisterType<SceneQuickView>("Esri.Samples", 1, 0, "SceneView");
qmlRegisterType<ShowExploratoryViewshedFromGeoElementInScene>("Esri.Samples", 1, 0, "ShowExploratoryViewshedFromGeoElementInSceneSample");
}
void ShowExploratoryViewshedFromGeoElementInScene::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 ExploratoryGeoElementViewshed(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, &ShowExploratoryViewshedFromGeoElementInScene::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 ShowExploratoryViewshedFromGeoElementInScene::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 ShowExploratoryViewshedFromGeoElementInScene::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 ShowExploratoryViewshedFromGeoElementInScene::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();
}
}