Viewshed (camera)

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Sample viewer app

This sample demonstrates how to calculate a Viewshed from a SceneView's current Camera Viewpoint.

screenshot

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

The sample will start with a viewshed created from the initial camera location, so only the visible (green) portion of the viewshed will be visible. Move around the scene to see the obstructed (red) portions. Click the 'Update from Camera' button to update the viewshed to the current camera position.

How it works

  1. Get the current camera from the scene with SceneView::currentViewpointCamera.
  2. Create a LocationViewshed, passing in the Camera and a min/max distance.
  3. Update the viewshed from a camera.

Relevant API

  • AnalysisOverlay
  • ArcGISScene
  • ArcGISTiledElevationSource
  • Camera
  • IntegratedMeshLayer
  • LocationViewshed
  • SceneView

About the data

The scene shows an integrated mesh layer of Girona, Spain with the World Elevation source image service both hosted on ArcGIS Online.

Tags

3D, integrated mesh, Scene, viewshed, visibility analysis

Sample Code

ViewshedCamera.cppViewshedCamera.cppViewshedCamera.hViewshedCamera.qml
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// [WriteFile Name=ViewshedCamera, 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 "ViewshedCamera.h"

#include "ArcGISTiledElevationSource.h"
#include "Scene.h"
#include "SceneQuickView.h"
#include "ArcGISSceneLayer.h"
#include "AnalysisOverlay.h"
#include "Point.h"
#include "Camera.h"
#include "Viewpoint.h"
#include "LocationViewshed.h"
#include "IntegratedMeshLayer.h"

using namespace Esri::ArcGISRuntime;

ViewshedCamera::ViewshedCamera(QQuickItem* parent /* = nullptr */):
  QQuickItem(parent)
{
}

void ViewshedCamera::init()
{
  // Register classes for QML
  qmlRegisterType<SceneQuickView>("Esri.Samples", 1, 0, "SceneView");
  qmlRegisterType<ViewshedCamera>("Esri.Samples", 1, 0, "ViewshedCameraSample");
}

void ViewshedCamera::componentComplete()
{
  QQuickItem::componentComplete();

  // Create a scene
  m_sceneView = findChild<SceneQuickView*>("sceneView");
  m_scene = new Scene(BasemapStyle::ArcGISImageryStandard, this);

  // Set a base surface
  Surface* surface = new Surface(this);
  surface->elevationSources()->append(
        new ArcGISTiledElevationSource(
          QUrl("https://elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/Terrain3D/ImageServer"),
          this));
  m_scene->setBaseSurface(surface);

  // Create and add the Girona, Spain integrated mesh layer
  IntegratedMeshLayer* gironaMeshLayer = new IntegratedMeshLayer(QUrl("https://tiles.arcgis.com/tiles/z2tnIkrLQ2BRzr6P/arcgis/rest/services/Girona_Spain/SceneServer"), this);
  m_scene->operationalLayers()->append(gironaMeshLayer);

  // Add an AnalysisOverlay to display the viewshed analysis result
  m_analysisOverlay = new AnalysisOverlay(this);
  m_sceneView->analysisOverlays()->append(m_analysisOverlay);

  // Set initial viewpoint
  setInitialViewpoint();

  // Add the Scene to the Sceneview
  m_sceneView->setArcGISScene(m_scene);
}

void ViewshedCamera::calculateViewshed()
{
  if (!m_viewshed)
  {
    // Create the viewshed
    const double minDistance = 1;
    const double maxDistance = 1000;
    m_viewshed = new LocationViewshed(m_sceneView->currentViewpointCamera(), minDistance, maxDistance, this);

    // display the frustum
    m_viewshed->setFrustumOutlineVisible(true);

    // Add the viewshed to the overlay
    m_analysisOverlay->analyses()->append(m_viewshed);
  }
  else
  {
    m_viewshed->updateFromCamera(m_sceneView->currentViewpointCamera());
  }
}

void ViewshedCamera::setInitialViewpoint()
{
  const double x_longitude = 2.82691;
  const double y_latitude = 41.985;
  const double z_altitude = 124.987;
  Point pt(x_longitude, y_latitude, z_altitude, SpatialReference(4326));

  const double heading = 332.131;
  const double pitch = 82.4732;
  const double roll = 0;
  Camera camera(pt, heading, pitch, roll);

  Viewpoint initViewpoint(pt, camera);
  m_scene->setInitialViewpoint(initViewpoint);
}

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