Question

以下代码没有给出我预期的结果。我期望将所有点作为多边形的节点，并且多边形包含所有点。如何正确使用API？此外，如果我将thresold设置为小于1，程序会进入某种无限循环。

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);
        }
    }
}

结果：

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

Answer 1

对我来说很好。我使用了ConcaveHull-0.2和geospark-1.1.3库。这是运行您的代码后的结果：

com.vividsolutions.jts.geom.GeometryFactory@1e81f4dc 真正真正真正真正真正（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）

此外，它的阈值<1.0也可以使用

如何使用OpenTripPlanner API获得正确的Concave Hull？

1 个答案: