Package org.locationtech.jts.algorithm

Class InteriorPointArea

java.lang.Object

org.locationtech.jts.algorithm.InteriorPointArea

public class InteriorPointArea
extends java.lang.Object

Computes a point in the interior of an areal geometry.

Algorithm

• Find a Y value which is close to the centre of the geometry's vertical extent but is different to any of it's Y ordinates.
• Create a horizontal bisector line using the Y value and the geometry's horizontal extent
• Find the intersection between the geometry and the horizontal bisector line. The intersection is a collection of lines and points.
• Pick the midpoint of the largest intersection geometry

KNOWN BUGS

• If a fixed precision model is used, in some cases this method may return a point which does not lie in the interior.

Version:

1.7

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static class	InteriorPointArea.SafeBisectorFinder	Finds a safe bisector Y ordinate by projecting to the Y axis and finding the Y-ordinate interval which contains the centre of the Y extent.

Field Summary

Fields

Modifier and Type	Field	Description
private GeometryFactory	factory
private Coordinate	interiorPoint
private double	maxWidth

Constructor Summary

Constructors

Constructor	Description
InteriorPointArea(Geometry g)	Creates a new interior point finder for an areal geometry.

Method Summary

Modifier and Type	Method	Description
private void	add(Geometry geom)	Tests the interior vertices (if any) defined by an areal Geometry for the best inside point.
private void	addPolygon(Geometry geometry)	Finds an interior point of a Polygon.
private static double	avg(double a, double b)
static Coordinate	centre(Envelope envelope)	Returns the centre point of the envelope.
Coordinate	getInteriorPoint()	Gets the computed interior point.
protected LineString	horizontalBisector(Geometry geometry)
private Geometry	widestGeometry(Geometry geometry)
private Geometry	widestGeometry(GeometryCollection gc)

Methods inherited from class java.lang.Object

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

Field Detail

factory

private GeometryFactory factory

interiorPoint

private Coordinate interiorPoint

maxWidth

private double maxWidth

Constructor Detail

InteriorPointArea

public InteriorPointArea(Geometry g)

Creates a new interior point finder for an areal geometry.

Parameters:

g - an areal geometry

Method Detail

avg

private static double avg(double a,
                          double b)

getInteriorPoint

public Coordinate getInteriorPoint()

Gets the computed interior point.

Returns:

the coordinate of an interior point

add

private void add(Geometry geom)

Tests the interior vertices (if any) defined by an areal Geometry for the best inside point. If a component Geometry is not of dimension 2 it is not tested.

Parameters:

geom - the geometry to add

addPolygon

private void addPolygon(Geometry geometry)

Finds an interior point of a Polygon.

Parameters:

geometry - the geometry to analyze

widestGeometry

private Geometry widestGeometry(Geometry geometry)

widestGeometry

private Geometry widestGeometry(GeometryCollection gc)

horizontalBisector

protected LineString horizontalBisector(Geometry geometry)

centre

public static Coordinate centre(Envelope envelope)

Returns the centre point of the envelope.

Parameters:

envelope - the envelope to analyze

Returns:

the centre of the envelope