org.opensphere.geometry.algorithm

Class ConcaveHull

java.lang.Object

org.opensphere.geometry.algorithm.ConcaveHull

public class ConcaveHull
extends Object

Computes a concave hull of a Geometry which is a concave Geometry that contains all the points in the input Geometry. The concave hull is not be defined as unique; here, it is defined according to a threshold which is the maximum length of border edges of the concave hull.

Uses the Duckham and al. (2008) algorithm defined in the paper untitled "Efficient generation of simple polygons for characterizing the shape of a set of points in the plane".

Author:

Eric Grosso

Field Summary

Fields

Modifier and Type	Field and Description
HashMap<com.vividsolutions.jts.geom.Coordinate,Integer>	coordinates
HashMap<Integer,Edge>	edges
TreeMap<Integer,Edge>	lengths
HashMap<com.vividsolutions.jts.geom.LineSegment,Integer>	segments
HashMap<Integer,Edge>	shortLengths
HashMap<Integer,Triangle>	triangles
HashMap<Integer,Vertex>	vertices

Constructor Summary

Constructors

Constructor and Description
ConcaveHull(com.vividsolutions.jts.geom.GeometryCollection geometries, double threshold) Create a new concave hull construction for the input GeometryCollection.
ConcaveHull(com.vividsolutions.jts.geom.Geometry geometry, double threshold) Create a new concave hull construction for the input Geometry.

Method Summary

Modifier and Type	Method and Description
com.vividsolutions.jts.geom.Geometry	getConcaveHull() Returns a Geometry that represents the concave hull of the input geometry according to the threshold.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

segments

public HashMap<com.vividsolutions.jts.geom.LineSegment,Integer> segments

edges

public HashMap<Integer,Edge> edges

triangles

public HashMap<Integer,Triangle> triangles

lengths

public TreeMap<Integer,Edge> lengths

shortLengths

public HashMap<Integer,Edge> shortLengths

coordinates

public HashMap<com.vividsolutions.jts.geom.Coordinate,Integer> coordinates

vertices

public HashMap<Integer,Vertex> vertices

Constructor Detail

ConcaveHull

public ConcaveHull(com.vividsolutions.jts.geom.Geometry geometry,
                   double threshold)

Create a new concave hull construction for the input Geometry.

Parameters:

geometry -

threshold -

ConcaveHull

public ConcaveHull(com.vividsolutions.jts.geom.GeometryCollection geometries,
                   double threshold)

Create a new concave hull construction for the input GeometryCollection.

Parameters:

geometries -

threshold -

Method Detail

getConcaveHull

public com.vividsolutions.jts.geom.Geometry getConcaveHull()

Returns a Geometry that represents the concave hull of the input geometry according to the threshold. The returned geometry contains the minimal number of points needed to represent the concave hull.

Returns:

if the concave hull contains 3 or more points, a Polygon; 2 points, a LineString; 1 point, a Point; 0 points, an empty GeometryCollection.