Package org.tinfour.utils

Class VisvalingamLineSimplification

java.lang.Object

org.tinfour.utils.VisvalingamLineSimplification

public class VisvalingamLineSimplification
extends Object

Provides an implementation of Visvalingam's algorithm for simplifying lines by repeated elimination of the smallest area features.

This class is based on the algorithm described in Visvalingam, M. & Whyatt, Duncan. (1993). Line generalisation by repeated elimination of points. Cartographic Journal, The. 30. 46-51. 10.1179/000870493786962263.

Constructor Summary

Constructors

Constructor	Description
VisvalingamLineSimplification()	Standard constructor.

Method Summary

Modifier and Type	Method	Description
void	report(PrintStream ps)	Print summary information about the line simplification.
int	simplify(int nPoints, double[] xy, double areaThreshold)	Simplify the geometry of the input line or polygon by progressively removing points related to small-area features.

Methods inherited from class java.lang.Object

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

Constructor Detail

VisvalingamLineSimplification

public VisvalingamLineSimplification()

Standard constructor.

Method Detail

simplify

public int simplify(int nPoints,
                    double[] xy,
                    double areaThreshold)

Simplify the geometry of the input line or polygon by progressively removing points related to small-area features. The algorithm repeatedly inspects a chain of points to identify the set of three sequential points that forms the smallest area, it eliminates then, and continues.

Coordinates are given as an array in the order (x0, y0, x1, y1, etc.).

Parameters:

nPoints - the number of points in the feature.

xy - the coordinates of the feature

areaThreshold - the area threshold to be used as a reduction criterion.

Returns:

the number of points remaining after the thinning operation.

report

public void report(PrintStream ps)

Print summary information about the line simplification.

Parameters:

ps - a valid instance.