Line of sight (location)

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This sample demonstrates how to perform a line of sight analysis between two points in a SceneView.

screenshot

Use case

A line of sight analysis can be used to assess whether a view is obstructed between an observer and a target. Obstructing features could either be natural, like topography, or man-made, like buildings. Consider an events planning company wanting to commemorate a national event by lighting sequential beacons across hill summits or roof tops. To guarantee a successful event, ensuring an unobstructed line of sight between neighboring beacons would allow each beacon to be activated as intended.

How to use the sample

The sample loads with a preset observer and target location, linked by a colored line. A red segment on the line means the view between observer and target is obstructed, whereas green means the view is unobstructed.

Click to turn on the mouse move event listener, then move the mouse to update the target location in real time. Click again to lock the target location.

How it works

  1. Create an AnalysisOverlay and add it to the scene view.
  2. Create a LocationLineOfSight with initial observer and target locations and add it to the analysis overlay.
  3. Capture mouse movement with the mousePositionChanged signal. Turn the screen point into a scene point with sceneView.screenToLocation(screenPoint).
  4. Update the target location with lineOfSight.setTargetLocation(scenePoint).

Relevant API

  • AnalysisOverlay
  • ArcGISTiledElevationSource
  • LocationLineOfSight
  • SceneView
  • Surface

Tags

3D, line of sight, visibility, visibility analysis

Sample Code

LineOfSightLocation.qml
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// [WriteFile Name=LineOfSightLocation, 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 QtQuick.Controls
import Esri.ArcGISExtras
import Esri.ArcGISRuntime

Rectangle {
    clip: true
    width: 800
    height: 600


    property bool calculating: false

    SceneView {
        id: sceneView
        anchors.fill: parent
        focus: true
        Component.onCompleted: {
            // Set the focus on SceneView to initially enable keyboard navigation
            forceActiveFocus();
        }

        Scene {
            id: scene
            Basemap {
                initStyle: Enums.BasemapStyleArcGISTopographic
            }

            Surface {
                ArcGISTiledElevationSource {
                    url: "https://elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/Terrain3D/ImageServer"
                }
            }

            onLoadStatusChanged: {
                if (loadStatus === Enums.LoadStatusLoaded) {
                    setInitialViewpoint();
                }
            }
        }

        // Add an Analysis Overlay
        AnalysisOverlay {
            id: analysisOverlay

            // Declare a LineOfSight and set initial observer and target locations
            LocationLineOfSight {
                id: locationLineOfSight
                visible: true
                observerLocation: Point {
                    x: -73.06958032962375
                    y: -49.253112971555446
                    z: 2000
                    spatialReference: Factory.SpatialReference.createWgs84()
                }
                targetLocation: Point {
                    x: -73.079266999709162
                    y: -49.300457676730559
                    z: 1312
                    spatialReference: Factory.SpatialReference.createWgs84()
                }

                // Configure the LoS color and width
                Component.onCompleted: {
                    LineOfSight.setVisibleColor("cyan");
                    LineOfSight.setObstructedColor("magenta");
                    LineOfSight.setLineWidth(2);
                }
            }
        }

        // Update the target location as you tap the map
        onMouseClicked: mouse => locationLineOfSight.targetLocation = sceneView.screenToBaseSurface(mouse.x, mouse.y);
        onMousePressedAndHeld: calculating = true;
        onMouseReleased: calculating = false;
        onMousePositionChanged: mouse => {
            if (!calculating)
                return;

            locationLineOfSight.targetLocation = sceneView.screenToBaseSurface(mouse.x, mouse.y);
        }
    }

    function setInitialViewpoint() {
        // Set a viewpoint
        const point = ArcGISRuntimeEnvironment.createObject("Point", {
                                                                x: -73.0815,
                                                                y: -49.3272,
                                                                z: 4059,
                                                                spatialReference: Factory.SpatialReference.createWgs84()
                                                            });

        const camera = ArcGISRuntimeEnvironment.createObject("Camera", {
                                                                 location: point,
                                                                 heading: 11,
                                                                 pitch: 62,
                                                                 roll: 0
                                                             });

        sceneView.setViewpointCamera(camera);
    }
}

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