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Generate convex hull polygon(s) from multiple input geometries.

Image of convex hull list

Use case

Creating a convex hull allows for analysis to define the polygon with the least possible perimeter that encloses a group of geometric shapes. As a visual analogy, consider a set of nails in a board where the convex hull is a rubber band stretched around the outermost nails.

How to use the sample

Click the ‘Create Convex Hull’ button to create convex hull(s) from the polygon graphics. If the ‘Union’ checkbox is checked, the resulting output will be one polygon being the convex hull for the two input polygons. If the ‘Union’ checkbox is un-checked, the resulting output will have two convex hull polygons - one for each of the two input polygons. Click the ‘Clear’ button to start over.

How it works

  1. Create an ArcGISMap and display it in a MapView.
  2. Create two input polygon graphics and add them to a GraphicsOverlay.
  3. Call GeometryEngine.convexHull(inputGeometries, boolean), specifying a list of geometries for which to generate the convex hull. Set the boolean parameter to true to generate a convex hull for the union of the geometries. Set it to false to create a convex hull for each individual geometry.
  4. Loop through the returned geometries and add them as graphics for display on the map.

Relevant API

  • GeometryEngine
  • Graphic
  • GraphicsOverlay

Tags

analysis, geometry, outline, perimeter, union

Sample Code

module-info.java module-info.java ConvexHullListSample.java
/*
* Copyright 2022 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.
*/
module com.esri.samples.convex_hull_list {
// require ArcGIS Maps SDK for Java module
requires com.esri.arcgisruntime;
// handle SLF4J http://www.slf4j.org/codes.html#StaticLoggerBinder
requires org.slf4j.nop;
// require JavaFX modules that the application uses
requires javafx.graphics;
requires javafx.controls;
exports com.esri.samples.convex_hull_list;
}