Viewshed geoelement

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Sample viewer app

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

Image of viewshed for geoelement

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

Click to set a destination for the vehicle (a GeoElement). The vehicle will 'drive' towards the clicked location. The 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 a GeoElementViewshed with configuration for the viewshed analysis.
  4. Add the viewshed to an AnalysisOverlay and add the overlay to the scene.
  5. Configure the SceneView OrbitGeoElementCameraController to orbit the vehicle.

About the data

This sample shows a Johannesburg, South Africa Scene from ArcGIS Online. The sample uses a Tank model scene symbol hosted as an item on ArcGIS Online.

Relevant API

  • AnalysisOverlay
  • GeodeticDistanceResult
  • GeoElementViewshed
  • GeometryEngine.distanceGeodetic (used to animate the vehicle)
  • ModelSceneSymbol
  • OrbitGeoElementCameraController

Tags

3D, analysis, buildings, model, scene, viewshed, visibility analysis

Sample Code

ViewshedGeoElementSample.java
                                                                                                                                                                                                                    
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/*
 * 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.
 */

package com.esri.samples.viewshed_geoelement;

import java.io.File;

import javafx.animation.KeyFrame;
import javafx.animation.Timeline;
import javafx.application.Application;
import javafx.geometry.Point2D;
import javafx.scene.Scene;
import javafx.scene.input.MouseButton;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
import javafx.util.Duration;

import com.esri.arcgisruntime.geoanalysis.GeoElementViewshed;
import com.esri.arcgisruntime.geometry.AngularUnit;
import com.esri.arcgisruntime.geometry.AngularUnitId;
import com.esri.arcgisruntime.geometry.GeodeticCurveType;
import com.esri.arcgisruntime.geometry.GeodeticDistanceResult;
import com.esri.arcgisruntime.geometry.GeometryEngine;
import com.esri.arcgisruntime.geometry.LinearUnit;
import com.esri.arcgisruntime.geometry.LinearUnitId;
import com.esri.arcgisruntime.geometry.Point;
import com.esri.arcgisruntime.geometry.SpatialReferences;
import com.esri.arcgisruntime.layers.ArcGISSceneLayer;
import com.esri.arcgisruntime.mapping.ArcGISScene;
import com.esri.arcgisruntime.mapping.ArcGISTiledElevationSource;
import com.esri.arcgisruntime.mapping.Basemap;
import com.esri.arcgisruntime.mapping.Surface;
import com.esri.arcgisruntime.mapping.view.AnalysisOverlay;
import com.esri.arcgisruntime.mapping.view.Graphic;
import com.esri.arcgisruntime.mapping.view.GraphicsOverlay;
import com.esri.arcgisruntime.mapping.view.LayerSceneProperties;
import com.esri.arcgisruntime.mapping.view.OrbitGeoElementCameraController;
import com.esri.arcgisruntime.mapping.view.SceneView;
import com.esri.arcgisruntime.symbology.ModelSceneSymbol;
import com.esri.arcgisruntime.symbology.Renderer;
import com.esri.arcgisruntime.symbology.SceneSymbol;
import com.esri.arcgisruntime.symbology.SimpleRenderer;

public class ViewshedGeoElementSample extends Application {

  private SceneView sceneView;
  private Graphic tank;
  private Timeline animation;
  private Point waypoint;

  private static final LinearUnit METERS = new LinearUnit(LinearUnitId.METERS);
  private static final AngularUnit DEGREES = new AngularUnit(AngularUnitId.DEGREES);

  @Override
  public void start(Stage stage) {

    try {

      // create stack pane and JavaFX app scene
      StackPane stackPane = new StackPane();
      Scene fxScene = new Scene(stackPane);

      // set title, size, and add JavaFX scene to stage
      stage.setTitle("Viewshed GeoElement Sample");
      stage.setWidth(800);
      stage.setHeight(700);
      stage.setScene(fxScene);
      stage.show();

      // create a scene and add a basemap to it
      ArcGISScene scene = new ArcGISScene();
      scene.setBasemap(Basemap.createImagery());

      // add the SceneView to the stack pane
      sceneView = new SceneView();
      sceneView.setArcGISScene(scene);
      stackPane.getChildren().addAll(sceneView);

      // add base surface for elevation data
      Surface surface = new Surface();
      final String localElevationImageService = "https://scene.arcgis.com/arcgis/rest/services/BREST_DTM_1M/ImageServer";
      surface.getElevationSources().add(new ArcGISTiledElevationSource(localElevationImageService));
      scene.setBaseSurface(surface);

      // add a scene layer
      final String buildings = "https://tiles.arcgis.com/tiles/P3ePLMYs2RVChkJx/arcgis/rest/services/Buildings_Brest/SceneServer/layers/0";
      ArcGISSceneLayer sceneLayer = new ArcGISSceneLayer(buildings);
      scene.getOperationalLayers().add(sceneLayer);

      // create a graphics overlay for the tank
      GraphicsOverlay graphicsOverlay = new GraphicsOverlay();
      graphicsOverlay.getSceneProperties().setSurfacePlacement(LayerSceneProperties.SurfacePlacement.RELATIVE);
      sceneView.getGraphicsOverlays().add(graphicsOverlay);

      // set up heading expression for tank
      SimpleRenderer renderer3D = new SimpleRenderer();
      Renderer.SceneProperties renderProperties = renderer3D.getSceneProperties();
      renderProperties.setHeadingExpression("[HEADING]");
      graphicsOverlay.setRenderer(renderer3D);

      // create a graphic of a tank
      String modelURI = new File(System.getProperty("data.dir"), "./samples-data/bradley_low_3ds/bradle.3ds").getAbsolutePath();
      ModelSceneSymbol tankSymbol = new ModelSceneSymbol(modelURI.replace("\\", "/"), 10.0);
      tankSymbol.setHeading(90);
      tankSymbol.setAnchorPosition(SceneSymbol.AnchorPosition.BOTTOM);
      tankSymbol.loadAsync();
      tank = new Graphic(new Point(-4.506390, 48.385624, SpatialReferences.getWgs84()), tankSymbol);
      tank.getAttributes().put("HEADING", 0.0);
      graphicsOverlay.getGraphics().add(tank);

      // create a viewshed to attach to the tank
      GeoElementViewshed geoElementViewshed = new GeoElementViewshed(tank, 90.0, 40.0, 0.1, 250.0, 0.0, 0.0);
      // offset viewshed observer location to top of tank
      geoElementViewshed.setOffsetZ(3.0);

      // create an analysis overlay to add the viewshed to the scene view
      AnalysisOverlay analysisOverlay = new AnalysisOverlay();
      analysisOverlay.getAnalyses().add(geoElementViewshed);
      sceneView.getAnalysisOverlays().add(analysisOverlay);

      // set the waypoint where the user clicks
      sceneView.setOnMouseClicked(e -> {
        if (e.isStillSincePress() && e.getButton() == MouseButton.PRIMARY) {
          // create a point from where the user clicked
          Point2D point = new Point2D(e.getX(), e.getY());

          // set the new waypoint
          waypoint = sceneView.screenToBaseSurface(point);
        }
      });

      // set camera controller to follow tank
      OrbitGeoElementCameraController cameraController = new OrbitGeoElementCameraController(tank, 200.0);
      cameraController.setCameraPitchOffset(45.0);
      sceneView.setCameraController(cameraController);

      // create a timeline to animate the tank
      animation = new Timeline();
      animation.setCycleCount(-1);
      animation.getKeyFrames().add(new KeyFrame(Duration.millis(100), e -> animate()));
      animation.play();

    } catch (Exception e) {
      // on any error, display the stack trace.
      e.printStackTrace();
    }
  }

  /**
   * Moves the tank toward the current waypoint a short distance.
   */
  private void animate() {
    if (waypoint != null) {
      // get current location and distance from waypoint
      Point location = (Point) tank.getGeometry();
      GeodeticDistanceResult distance = GeometryEngine.distanceGeodetic(location, waypoint, METERS, DEGREES,
          GeodeticCurveType.GEODESIC);

      // move toward waypoint a short distance
      location = GeometryEngine.moveGeodetic(location, 1.0, METERS, distance.getAzimuth1(), DEGREES,
          GeodeticCurveType.GEODESIC);
      tank.setGeometry(location);

      // rotate toward waypoint
      double heading = (double) tank.getAttributes().get("HEADING");
      tank.getAttributes().put("HEADING", heading + ((distance.getAzimuth1() - heading) / 10));

      // reached waypoint, stop moving
      if (distance.getDistance() <= 5) {
        waypoint = null;
      }
    }
  }

  /**
   * Stops and releases all resources used in application.
   */
  @Override
  public void stop() {

    // stop the animation
    animation.stop();

    if (sceneView != null) {
      sceneView.dispose();
    }
  }

  /**
   * Opens and runs application.
   *
   * @param args arguments passed to this application
   */
  public static void main(String[] args) {

    Application.launch(args);
  }

}

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