CODEWITHSUNDEEP
concave-hullopentripplanner
Paul Z Wu
Paul Z Wu

Reputation: 575

How to get the correct Concave Hull using OpenTripPlanner API?

The following code does not give me the result I expected. I expect to have all the points as the nodes of the polygon and the polygon contains all the points. How to use the API correctly? Also if I set thresold less than 1, the program got into some kind infinite loop.

import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.Geometry;
import com.vividsolutions.jts.geom.GeometryCollection;
import com.vividsolutions.jts.geom.GeometryFactory;
import com.vividsolutions.jts.geom.Point;
import java.util.Set;
import org.geotools.geometry.jts.JTSFactoryFinder;
import org.opensphere.geometry.algorithm.ConcaveHull;


public class ConcaveHullTrial {

    public static void main(String args[]) {

        ConcaveHull cch = null;
        com.vividsolutions.jts.geom.Point point[] = new Point[5];
        Set<GeometryFactory> testing = JTSFactoryFinder.getGeometryFactories();
        for (GeometryFactory f : testing) {
            System.out.println(f);
        }
        GeometryFactory gf = JTSFactoryFinder.getGeometryFactory();
        point[0] = gf.createPoint(new Coordinate(0.0, 0.0));
        point[1] = gf.createPoint(new Coordinate(0.0, 2.0));
        point[2] = gf.createPoint(new Coordinate(2.0, 0.0));
        point[3] = gf.createPoint(new Coordinate(2.0, 2.0));
        point[4] = gf.createPoint(new Coordinate(1.8, 1.5));

        GeometryCollection gc = new GeometryCollection(point, gf);
        double threshold = 4;
        cch = new ConcaveHull(gc, threshold);
        Geometry hull = cch.getConcaveHull();
        for (int i = 0; i < 5; i++) {
            System.out.println(hull.covers(point[i]));
        }
        for (Coordinate c: hull.getCoordinates()) {
            System.out.println(c);
        }
    }
}

Results:

false
true
false
true
false
(0.0, 2.0, NaN)
(2.0, 2.0, NaN)

Upvotes: 0

Views: 392

Answers (1)

Ahmad Sepahi
Ahmad Sepahi

Reputation: 51

it works fine for me. I used ConcaveHull-0.2 and geospark-1.1.3 libs. Here is my result after running your piece of code:

com.vividsolutions.jts.geom.GeometryFactory@1e81f4dc true true true true true (0.0, 0.0, NaN) (2.0, 0.0, NaN) (2.0, 2.0, NaN) (0.0, 2.0, NaN) (0.0, 0.0, NaN)

In addition, it worked with threshold < 1.0

Upvotes: 0

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