Module imagingbook.common

Package imagingbook.common.geometry.hulls

Class ConvexHull

java.lang.Object

imagingbook.common.geometry.hulls.ConvexHull

All Implemented Interfaces:

ShapeProducer

public class ConvexHull
extends Object
implements ShapeProducer

This class calculate the convex hull of a 2D point set. It is based on the convex hull implementation provided by the Apache Commons Math library, in particular classes ConvexHull2D and MonotoneChain [1]. See Sec. 8.4.2 of [2] for additional details.

[1] https://commons.apache.org/proper/commons-math/index.html
[2] W. Burger, M.J. Burge, Digital Image Processing – An Algorithmic Introduction, 3rd ed, Springer (2022).

Version:

2022/06/24

Field Summary

Fields

Modifier and Type	Field	Description
static final double	DefaultContainsTolerance

Constructor Summary

Constructors

Constructor	Description
ConvexHull(Pnt2d[] points)	Constructor, creates a AxisAlignedBoundingBox instance from an array of Pnt2d points.
ConvexHull(Iterable<Pnt2d> points)	Constructor, creates a ConvexHull instance from an Iterable over Pnt2d.

Method Summary

Modifier and Type	Method	Description
boolean	contains(Pnt2d p)
boolean	contains(Pnt2d p, double tolerance)	Checks if this convex hull contains the specified point.
Shape	getShape(double scale)	Returns a scaled Shape for this object (default scale is 1).
Pnt2d[]	getVertices()	Returns a sequence of 2D points on the convex hull (in counter-clockwise order).

Methods inherited from class java.lang.Object

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

Methods inherited from interface imagingbook.common.geometry.shape.ShapeProducer

getShape, getShapes, getShapes

Field Details

DefaultContainsTolerance

public static final double DefaultContainsTolerance

See Also:

• Constant Field Values

Constructor Details

ConvexHull

public ConvexHull(Iterable<Pnt2d> points)

Constructor, creates a ConvexHull instance from an Iterable over Pnt2d. At least one distinct point is required.

Parameters:

points - an iterator over 2D points

ConvexHull

public ConvexHull(Pnt2d[] points)

Constructor, creates a AxisAlignedBoundingBox instance from an array of Pnt2d points. At least one distinct point is required.

Parameters:

points - an array of 2D points

Method Details

getVertices

public Pnt2d[] getVertices()

Returns a sequence of 2D points on the convex hull (in counter-clockwise order).

Returns:

sequence of 2D points on the convex hull

getShape

public Shape getShape(double scale)

Description copied from interface: ShapeProducer

Returns a scaled Shape for this object (default scale is 1). Must be defined by implementing classes. The interpretation of the scale factor is left to the implementing class. For example, for Pnt2d it specifies the size of the marker (see Pnt2d.getShape(double).

Specified by:

getShape in interface ShapeProducer

Parameters:

scale - the scale of the shape

Returns:

a Shape instance

contains

public boolean contains(Pnt2d p)

contains

public boolean contains(Pnt2d p,
 double tolerance)

Checks if this convex hull contains the specified point. This method is used instead of Path2D.contains(double, double) to avoid false results due to roundoff errors.

Parameters:

p - some 2D point

tolerance - positive quantity for being outside

Returns:

true if the point is inside the hull