JTS Geometry relationship judgment and analysis

 

Relationship judgment

1. The relationship between Geometry is as follows:

Equals:	The geometric shapes are topologically equal.
Disjoint:	The geometry has no points in common.
Intersects:	Geometric shapes have at least one common point (different from disjoint)
Touches:	The geometry has at least one common boundary point, but no internal points.
Crosses:	The geometric shapes share some but not all internal points.
With (Within):	The lines of geometry A are all inside geometry B.
Contains:	Lines of geometry B are all inside geometry A (different from inclusion)
Overlaps:	The geometric shapes share some but not all common points, and they have their own same area at the intersection.

1. The following example shows how to use Equals, Disjoint, Intersects, Within operations:

package com.alibaba.autonavi;

import com.vividsolutions.jts.geom.*;
import com.vividsolutions.jts.io.ParseException;
import com.vividsolutions.jts.io.WKTReader;

/**
 * gemotry之间的关系
 * @author xingxing.dxx
 *
 */
public class GeometryRelated {

    private GeometryFactory geometryFactory = new GeometryFactory();
    
    /**
     *  两个几何对象是否是重叠的
     * @return
     * @throws ParseException
     */
    public boolean equalsGeo() throws ParseException{
        WKTReader reader = new WKTReader( geometryFactory );
        LineString geometry1 = (LineString) reader.read("LINESTRING(0 0, 2 0, 5 0)");
        LineString geometry2 = (LineString) reader.read("LINESTRING(5 0, 0 0)");
        return geometry1.equals(geometry2);//true
    }
    
    /**
     * 几何对象没有交点(相邻)
     * @return
     * @throws ParseException
     */
    public boolean disjointGeo() throws ParseException{
        WKTReader reader = new WKTReader( geometryFactory );
        LineString geometry1 = (LineString) reader.read("LINESTRING(0 0, 2 0, 5 0)");
        LineString geometry2 = (LineString) reader.read("LINESTRING(0 1, 0 2)");
        return geometry1.disjoint(geometry2);
     * @throws ParseException
     * @return
     * At least one common point (intersection)
    / **
    }
    
     * / 
    public boolean intersectsGeo() throws ParseException{
        WKTReader reader = new WKTReader (geometryFactory); 
        LineString geometry1 = (LineString) reader.read ("LINESTRING (0 0, 2 0, 5 0)"); 
        LineString geometry2 = (LineString) reader.read ("LINESTRING (0 0, 0 2) "); 
        Geometry interPoint = geometry1.intersection (geometry2); // Intersection point 
        System.out.println (interPoint.toText ()); // Output POINT (0 0) 
        return geometry1.intersects (geometry2) ; 
    } 

    / ** 
     * Determine whether the point (x, y) with x and y coordinates is in the Polygon represented by geometry 
     * @param x 
     * @param y 
     * @param geometry wkt format 
     * @return 
     * /
    public boolean withinGeo(double x,double y,String geometry) throws ParseException {

        Coordinate coord = new Coordinate(x,y);
        Point point = geometryFactory.createPoint( coord );

        WKTReader reader = new WKTReader( geometryFactory );
        Polygon polygon = (Polygon) reader.read(geometry);
        return point.within(polygon);
    }
    /**
     * @param args
     * @throws ParseException 
     */
    public static void main(String[] args) throws ParseException {
        GeometryRelated gr = new GeometryRelated();
        System.out.println(gr.equalsGeo());
        System.out.println(gr.disjointGeo());
        System.out.println(gr.intersectsGeo());
        System.out.println(gr.withinGeo(5,5,"POLYGON((0 0, 10 0, 10 10, 0 10,0 0))"));
    }

}

 

Relationship analysis

1. There are several types of relationship analysis

Buffer analysis (Buffer)	Contain all polygons and multi-polygons within a specified distance
Convex Hull Analysis (ConvexHull)	Convex hull polygon containing all points of geometric shape (outsourcing polygon)
Intersection	A∩B intersection operation is the set of all common points in polygon AB
Joint Analysis (Union)	The joint operation of AUB AB is the set of all points of AB
Difference Analysis (Difference)	(AA∩B) The difference analysis of AB shape is the set of all points in A that are not in B
Symmetric difference analysis (SymDifference)	(AUB-A∩B) The symmetric difference analysis of AB shape is the set of all points located in A or B but not in AB

 

 

 

 

 

 

 

 

 

     2. Let's take a look at specific examples

package com.alibaba.autonavi;

import java.util.ArrayList;
import java.util.List;

import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.Geometry;
import com.vividsolutions.jts.geom.GeometryFactory;
import com.vividsolutions.jts.geom.LineString;

/**
 * gemotry之间的关系分析
 *
 * @author xingxing.dxx
 */
public class Operation {

    private GeometryFactory geometryFactory = new GeometryFactory();

    /**
     * create a Point
     *
     * @param x
     * @param y
     * @return
     */
    public Coordinate point(double x, double y) {
        return new Coordinate(x, y);
    }


    / ** 
     * create a line 
     * 
     * @return 
     * / 
    public LineString createLine (List <Coordinate> points) { 
        Coordinate [] coords = (Coordinate []) points.toArray (new Coordinate [points.size ()]); 
        LineString line = geometryFactory.createLineString (coords); 
        return line; 
    } 

    / ** 
     * return polygons and multi-polygons within a specified distance 
     * 
     * @param a 
     * @param distance 
     * @return 
     * / 
    public Geometry bufferGeo (Geometry a, double distance ) { 
        return a.buffer (distance); 
    } 
     *

    /**
     * Return the distance between the closest two points in (A) and (B) 
     * @param a 
     * @param b 
     * @return 
     * / 
    public double distanceGeo (Geometry a, Geometry b) { 
        return a.distance (b); 
    } 

    / ** 
     * The intersection of two geometric objects 
     * 
     * @param a 
     * @param b 
     * @return 
     * / 
    public Geometry intersectionGeo (Geometry a, Geometry b) { 
        return a.intersection (b); 
    } 

    / ** 
     * Geometry Object merge 
     * 
     * @param a 
     * @param b 
     * @return 
     * / 
    public Geometry unionGeo (Geometry a, Geometry b) { 
        return a .union (b); 
    } 

    / ** 
     * Yes in A geometry object, but not in B geometry object
     *
     * @param a
     * @param b
     * @return
     */
    public Geometry differenceGeo(Geometry a, Geometry b) {
        return a.difference(b);
    }


    public static void main(String[] args) {
        Operation op = new Operation();
        //创建一条线
        List<Coordinate> points1 = new ArrayList<Coordinate>();
        points1.add(op.point(0, 0));
        points1.add(op.point(1, 3));
        points1.add(op.point(2, 3));
        LineString line1 = op.createLine(points1);
        //创建第二条线
        List<Coordinate> points2 = new ArrayList<Coordinate>();
        points2.add(op.point(3, 0));
        points2.add(op.point(3, 3));
        points2.add(op.point(5, 6));
        LineString line2 = op.createLine(points2);

        System.out.println(op.distanceGeo(line1, line2));//out 1.0
        System.out.println(op.intersectionGeo(line1, line2));//out GEOMETRYCOLLECTION EMPTY
        System.out.println(op.unionGeo(line1, line2)); //out MULTILINESTRING ((0 0, 1 3, 2 3), (3 0, 3 3, 5 6))
        System.out.println(op.differenceGeo(line1, line2));//out LINESTRING (0 0, 1 3, 2 3)
    }
}