package com.vividsolutions.jtsexample.technique;
import com.vividsolutions.jts.geom.*;
import com.vividsolutions.jts.io.WKTReader;
/**
* Shows a technique for using a zero-width buffer to compute
* the union of a collection of <b>polygonal</b> geometrys.
* The advantages of this technique are:
* <ul>
* <li>can avoid robustness issues
* <li>faster for large numbers of input geometries
* <li>handles GeometryCollections as input (although only the polygons will be buffered)
* </ul>
* Disadvantages are:
* <ul>
* <li>may not preserve input coordinate precision in some cases
* <li>only works for polygons
* </ul>
*
* @version 1.7
*/
public class PolygonUnionUsingBuffer {
public static void main(String[] args)
throws Exception
{
WKTReader rdr = new WKTReader();
Geometry[] geom = new Geometry[3];
geom[0] = rdr.read("POLYGON (( 100 180, 100 260, 180 260, 180 180, 100 180 ))");
geom[1] = rdr.read("POLYGON (( 80 140, 80 200, 200 200, 200 140, 80 140 ))");
geom[2] = rdr.read("POLYGON (( 160 160, 160 240, 240 240, 240 160, 160 160 ))");
unionUsingBuffer(geom);
}
public static void unionUsingBuffer(Geometry[] geom)
{
GeometryFactory fact = geom[0].getFactory();
Geometry geomColl = fact.createGeometryCollection(geom);
Geometry union = geomColl.buffer(0.0);
System.out.println(union);
}
}