Calculate a geodesic path between two points and measure its distance.
Use case
A geodesic distance provides an accurate, real-world distance between two points. Visualizing flight paths between cities is a common example of a geodesic operation since the flight path between two airports takes into account the curvature of the earth, rather than following the planar path between those points, which appears as a straight line on a projected map.
How to use the sample
Click anywhere on the map. A line graphic will display the geodesic line between the two points. In addition, text that indicates the geodesic distance between the two points will be updated. Click elsewhere and a new line will be created.
How it works
Create a Point in and display it as a Graphic.
Obtain a new point when a click occurs on the MapView and add this point as a graphic.
Create a Polyline from the two points.
Execute GeometryEngine.densifyGeodetic() by passing in the created polyine then create a graphic from the returned Geometry.
Execute GeometryEngine.lengthGeodetic() by passing in the two points and display the returned length on the screen.
Relevant API
GeometryEngine
About the data
The Imagery basemap style provides the global context for the displayed geodesic line.
Tags
densify, distance, geodesic, geodetic
Sample Code
GeodesicOperationsSample.java
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/*
* Copyright 2018 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.geodesic_operations;
import java.text.DecimalFormat;
import java.util.Arrays;
import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.geometry.Point2D;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.input.MouseButton;
import javafx.scene.layout.Background;
import javafx.scene.layout.BackgroundFill;
import javafx.scene.layout.CornerRadii;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Color;
import javafx.scene.paint.Paint;
import javafx.stage.Stage;
import com.esri.arcgisruntime.ArcGISRuntimeEnvironment;
import com.esri.arcgisruntime.geometry.GeodeticCurveType;
import com.esri.arcgisruntime.geometry.Geometry;
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.PointCollection;
import com.esri.arcgisruntime.geometry.Polyline;
import com.esri.arcgisruntime.geometry.SpatialReference;
import com.esri.arcgisruntime.geometry.SpatialReferences;
import com.esri.arcgisruntime.mapping.ArcGISMap;
import com.esri.arcgisruntime.mapping.BasemapStyle;
import com.esri.arcgisruntime.mapping.view.Graphic;
import com.esri.arcgisruntime.mapping.view.GraphicsOverlay;
import com.esri.arcgisruntime.mapping.view.MapView;
import com.esri.arcgisruntime.symbology.SimpleLineSymbol;
import com.esri.arcgisruntime.symbology.SimpleMarkerSymbol;
publicclassGeodesicOperationsSampleextendsApplication{
private MapView mapView;
privatefinal SpatialReference srWgs84 = SpatialReferences.getWgs84();
@Overridepublicvoidstart(Stage stage){
try {
// create stack pane and application scene StackPane stackPane = new StackPane();
Scene fxScene = new Scene(stackPane);
fxScene.getStylesheets().add(getClass().getResource("/geodesic_operations/style.css").toExternalForm());
// set title, size, and add scene to stage stage.setTitle("Geodesic Operations Sample");
stage.setWidth(800);
stage.setHeight(700);
stage.setScene(fxScene);
stage.show();
// authentication with an API key or named user is required to access basemaps and other location services String yourAPIKey = System.getProperty("apiKey");
ArcGISRuntimeEnvironment.setApiKey(yourAPIKey);
// create a map with the standard imagery basemap style ArcGISMap map = new ArcGISMap(BasemapStyle.ARCGIS_IMAGERY_STANDARD);
// create a map view and set the map to it mapView = new MapView();
mapView.setMap(map);
// create a graphics overlay GraphicsOverlay graphicsOverlay = new GraphicsOverlay();
mapView.getGraphicsOverlays().add(graphicsOverlay);
// add a graphic at JFK airport to represent the flight start location Point start = new Point(-73.7781, 40.6413, srWgs84);
SimpleMarkerSymbol locationMarker = new SimpleMarkerSymbol(SimpleMarkerSymbol.Style.CIRCLE, Color.BLUE, 10);
Graphic startLocation = new Graphic(start, locationMarker);
graphicsOverlay.getGraphics().add(startLocation);
// create a graphic for the destination Graphic endLocation = new Graphic();
endLocation.setSymbol(locationMarker);
graphicsOverlay.getGraphics().add(endLocation);
// create a graphic representing the geodesic path between the two locations Graphic path = new Graphic();
path.setSymbol(new SimpleLineSymbol(SimpleLineSymbol.Style.DASH, Color.BLUE, 5));
graphicsOverlay.getGraphics().add(path);
// create a label to show the distance Label distanceLabel = new Label();
DecimalFormat formatter = new DecimalFormat("#0.00 km");
distanceLabel.setText(formatter.format(0.0));
VBox labelBox = new VBox(distanceLabel);
labelBox.setBackground(new Background(new BackgroundFill(Paint.valueOf("rgba(0,0,0,0.3)"), CornerRadii.EMPTY,
Insets.EMPTY)));
labelBox.setAlignment(Pos.CENTER);
labelBox.setPadding(new Insets(5));
labelBox.setMaxSize(80, 20);
labelBox.getStyleClass().add("panel-region");
// create a linear unit for measuring the distance LinearUnit unitOfMeasurement = new LinearUnit(LinearUnitId.KILOMETERS);
// and a mouse click listener to get the user's input for the destination mapView.setOnMouseClicked(e -> {
if (e.isStillSincePress() && e.getButton() == MouseButton.PRIMARY) {
// change the end location's geometry to the clicked location Point2D point2D = new Point2D(e.getX(), e.getY());
Point destination = (Point) GeometryEngine.project(mapView.screenToLocation(point2D), srWgs84);
endLocation.setGeometry(destination);
// create a straight line path between the start and end locations PointCollection points = new PointCollection(Arrays.asList(start, destination), srWgs84);
Polyline polyline = new Polyline(points);
// densify the path as a geodesic curve and show it with the path graphic Geometry pathGeometry = GeometryEngine.densifyGeodetic(polyline, 1, unitOfMeasurement, GeodeticCurveType
.GEODESIC);
path.setGeometry(pathGeometry);
// calculate the path distancedouble distance = GeometryEngine.lengthGeodetic(pathGeometry, unitOfMeasurement, GeodeticCurveType.GEODESIC);
distanceLabel.setText(formatter.format(distance));
}
});
// add the scene view and label box to the stack pane stackPane.getChildren().addAll(mapView, labelBox);
StackPane.setMargin(labelBox, new Insets(10, 0, 0, 10));
StackPane.setAlignment(labelBox, Pos.TOP_LEFT);
} catch (Exception e) {
// on any error, display the stack trace. e.printStackTrace();
}
}
/**
* Stops and releases all resources used in application.
*/@Overridepublicvoidstop(){
if (mapView != null) {
mapView.dispose();
}
}
/**
* Opens and runs application.
*
* @param args arguments passed to this application
*/publicstaticvoidmain(String[] args){
Application.launch(args);
}
}