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Nearest vertex

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Find the closest vertex and coordinate of a geometry to a point.

Image of nearest vertex

Use case

Determine the shortest distance between a location and the boundary of an area. For example, developers can snap imprecise user clicks to a geometry if the click is within a certain distance of the geometry.

How to use the sample

Click anywhere on the map. An orange cross will show at that location. A blue circle will show the polygon's nearest vertex to the point that was clicked. A red diamond will appear at the coordinate on the geometry that is nearest to the point that was clicked. If clicked inside the geometry, the red and orange markers will overlap. The information box showing distance between the clicked point and the nearest vertex/coordinate will be updated with every new location clicked.

How it works

  1. Get a Geometry and a Point to check the nearest vertex against.
  2. Call GeometryEngine.nearestVertex(inputGeometry, point).
  3. Use the returned ProximityResult to get the Point representing the polygon vertex, and to determine the distance between that vertex and the clicked point.
  4. Call GeometryEngine.nearestCoordinate(inputGeometry, point).
  5. Use the returned ProximityResult to get the Point representing the coordinate on the polygon, and to determine the distance between that coordinate and the clicked point.

Relevant API

  • GeometryEngine
  • ProximityResult

Additional information

The value of ProximityResult.getDistance() is planar (Euclidean) distance. Planar distances are only accurate for geometries that have a defined projected coordinate system, which maintain the desired level of accuracy. The example polygon in this sample is defined in California State Plane Coordinate System - Zone 5 (WKID 2229), which maintains accuracy near Southern California. Accuracy declines outside the state plane zone.

Tags

analysis, coordinate, geometry, nearest, proximity, vertex

Sample Code

NearestVertexSample.java
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 /*  * 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.nearest_vertex;  import java.util.Arrays;  import javafx.application.Application; import javafx.beans.binding.Bindings; 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.SpatialReference; import com.esri.arcgisruntime.geometry.GeometryEngine; import com.esri.arcgisruntime.geometry.Point; import com.esri.arcgisruntime.geometry.PointCollection; import com.esri.arcgisruntime.geometry.Polygon; import com.esri.arcgisruntime.geometry.ProximityResult; import com.esri.arcgisruntime.layers.FeatureLayer; import com.esri.arcgisruntime.mapping.ArcGISMap; 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.portal.Portal; import com.esri.arcgisruntime.portal.PortalItem; import com.esri.arcgisruntime.symbology.SimpleFillSymbol; import com.esri.arcgisruntime.symbology.SimpleLineSymbol; import com.esri.arcgisruntime.symbology.SimpleMarkerSymbol;  public class NearestVertexSample extends Application {   private MapView mapView;  // California zone 5 (ftUS) state plane coordinate system  private final SpatialReference statePlaneCaliforniaZone5SpatialReference = SpatialReference.create(2229);   @Override  public void start(Stage stage) {   try {  // create stack pane and application scene  StackPane stackPane = new StackPane();  Scene scene = new Scene(stackPane);  scene.getStylesheets().add(getClass().getResource("/nearest_vertex/style.css").toExternalForm());   // set title, size, and add scene to stage  stage.setTitle("Nearest Vertex Sample");  stage.setWidth(800);  stage.setHeight(700);  stage.setScene(scene);  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 new feature layer from a new portal item  var portalItem = new PortalItem(  new Portal("https://arcgisruntime.maps.arcgis.com", false), "99fd67933e754a1181cc755146be21ca");  FeatureLayer usStatesGeneralizedLayer = new FeatureLayer(portalItem, 0);  // create a new map using the California zone 5 spatial reference  ArcGISMap map = new ArcGISMap(statePlaneCaliforniaZone5SpatialReference);  // add the feature layer to the map's list of base layers  map.getBasemap().getBaseLayers().add(usStatesGeneralizedLayer);   // create a map view and set the map to it  mapView = new MapView();  mapView.setMap(map);   // create a graphics overlay to show the polygon, clicked location, and nearest vertex/coordinate  GraphicsOverlay graphicsOverlay = new GraphicsOverlay();  mapView.getGraphicsOverlays().add(graphicsOverlay);   // construct a polygon from a point collection that uses the California zone 5 (ftUS) state plane coordinate system  PointCollection polygonPoints = new PointCollection(statePlaneCaliforniaZone5SpatialReference);  polygonPoints.addAll(Arrays.asList(  new Point(6627416.41469281, 1804532.53233782),  new Point(6669147.89779046, 2479145.16609522),  new Point(7265673.02678292, 2484254.50442408),  new Point(7676192.55880379, 2001458.66365744),  new Point(7175695.94143837, 1840722.34474458)));   // create a graphic for the polygon  Polygon polygon = new Polygon(polygonPoints);  SimpleLineSymbol polygonOutlineSymbol = new SimpleLineSymbol(SimpleLineSymbol.Style.SOLID, Color.LIMEGREEN, 2);  SimpleFillSymbol polygonFillSymbol = new SimpleFillSymbol(SimpleFillSymbol.Style.FORWARD_DIAGONAL, Color.LIMEGREEN, polygonOutlineSymbol);  Graphic polygonGraphic = new Graphic(polygon, polygonFillSymbol);  graphicsOverlay.getGraphics().add(polygonGraphic);   // create graphics for the clicked location, nearest coordinate, and nearest vertex markers  SimpleMarkerSymbol clickedLocationSymbol = new SimpleMarkerSymbol(SimpleMarkerSymbol.Style.X, Color.DARKORANGE, 15);  SimpleMarkerSymbol nearestCoordinateSymbol = new SimpleMarkerSymbol(SimpleMarkerSymbol.Style.DIAMOND, Color.RED, 10);  SimpleMarkerSymbol nearestVertexSymbol = new SimpleMarkerSymbol(SimpleMarkerSymbol.Style.CIRCLE, Color.BLUE, 15);  Graphic clickedLocationGraphic = new Graphic();  clickedLocationGraphic.setSymbol(clickedLocationSymbol);  Graphic nearestCoordinateGraphic = new Graphic();  nearestCoordinateGraphic.setSymbol(nearestCoordinateSymbol);  Graphic nearestVertexGraphic = new Graphic();  nearestVertexGraphic.setSymbol(nearestVertexSymbol);  graphicsOverlay.getGraphics().addAll(Arrays.asList(clickedLocationGraphic, nearestCoordinateGraphic, nearestVertexGraphic));   // create a label to show the distances between the nearest vertex and nearest coordinate to the clicked location  Label distancesLabel = new Label("");  distancesLabel.getStyleClass().add("panel-label");   // create a black background for the label  VBox controlsVBox = new VBox(6);  controlsVBox.setBackground(new Background(new BackgroundFill(Paint.valueOf("rgba(0,0,0,0.3)"), CornerRadii.EMPTY,  Insets.EMPTY)));  controlsVBox.setPadding(new Insets(10.0));  controlsVBox.setMaxSize(300, 50);  controlsVBox.getStyleClass().add("panel-region");  controlsVBox.getChildren().add(distancesLabel);  // hide it until the label text is set  controlsVBox.visibleProperty().bind(Bindings.createBooleanBinding(() -> !distancesLabel.getText().equals(""), distancesLabel.textProperty()));  controlsVBox.managedProperty().bind(controlsVBox.visibleProperty());   // get the nearest vertex and coordinate where the user clicks  mapView.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());   // create a map point from a point  Point mapPoint = mapView.screenToLocation(point);   // show where the user clicked  clickedLocationGraphic.setGeometry(mapPoint);   // show the nearest coordinate and vertex  ProximityResult nearestCoordinateResult = GeometryEngine.nearestCoordinate(polygon, mapPoint);  ProximityResult nearestVertexResult = GeometryEngine.nearestVertex(polygon, mapPoint);  nearestVertexGraphic.setGeometry(nearestVertexResult.getCoordinate());  nearestCoordinateGraphic.setGeometry(nearestCoordinateResult.getCoordinate());   // show the distances to the nearest vertex and nearest coordinate, converted from feet to miles  int vertexDistance = (int) (nearestVertexResult.getDistance() / 5280.0);  int coordinateDistance = (int) (nearestCoordinateResult.getDistance() / 5280.0);  distancesLabel.setText("Vertex distance: " + vertexDistance + " mi\nCoordinate distance: " + coordinateDistance + " mi");  }  });   // zoom to the polygon's extent  mapView.setViewpointGeometryAsync(polygon.getExtent(), 100);   // add the map view and label to the stack pane  stackPane.getChildren().addAll(mapView, controlsVBox);  StackPane.setAlignment(controlsVBox, Pos.TOP_LEFT);  StackPane.setMargin(controlsVBox, new Insets(10, 0, 0, 10));  } catch (Exception e) {  // on any error, display the stack trace.  e.printStackTrace();  }  }   /**  * Stops and releases all resources used in application.  */  @Override  public void stop() {   if (mapView != null) {  mapView.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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