org.locationtech.jts.operation.buffer

Class BufferInputLineSimplifier

java.lang.Object

org.locationtech.jts.operation.buffer.BufferInputLineSimplifier

public class BufferInputLineSimplifier
extends Object

Simplifies a buffer input line to remove concavities with shallow depth.

The major benefit of doing this is to reduce the number of points and the complexity of shape which will be buffered. This improve performance and robustness. It also reduces the risk of gores created by the quantized fillet arcs (although this issue should be eliminated by the offset curve generation logic).

A key aspect of the simplification is that it affects inside (concave or inward) corners only. Convex (outward) corners are preserved, since they are required to ensure that the generated buffer curve lies at the correct distance from the input geometry.

Another important heuristic used is that the end segments of linear inputs are never simplified. This ensures that the client buffer code is able to generate end caps faithfully. Ring inputs can have end segments removed by simplification.

No attempt is made to avoid self-intersections in the output. This is acceptable for use for generating a buffer offset curve, since the buffer algorithm is insensitive to invalid polygonal geometry. However, this means that this algorithm cannot be used as a general-purpose polygon simplification technique.

Author:

Martin Davis

Constructor Summary

Constructors

Constructor and Description
BufferInputLineSimplifier(Coordinate[] inputLine)

Method Summary

Modifier and Type	Method and Description
static Coordinate[]	simplify(Coordinate[] inputLine, double distanceTol) Simplify the input coordinate list.
Coordinate[]	simplify(double distanceTol) Simplify the input coordinate list.

Methods inherited from class java.lang.Object

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

Constructor Detail

BufferInputLineSimplifier

public BufferInputLineSimplifier(Coordinate[] inputLine)

Method Detail

simplify

public static Coordinate[] simplify(Coordinate[] inputLine,
                                    double distanceTol)

Simplify the input coordinate list. If the distance tolerance is positive, concavities on the LEFT side of the line are simplified. If the supplied distance tolerance is negative, concavities on the RIGHT side of the line are simplified.

Parameters:

inputLine - the coordinate list to simplify

distanceTol - simplification distance tolerance to use

Returns:

the simplified coordinate list

simplify

public Coordinate[] simplify(double distanceTol)

Simplify the input coordinate list. If the distance tolerance is positive, concavities on the LEFT side of the line are simplified. If the supplied distance tolerance is negative, concavities on the RIGHT side of the line are simplified.

Parameters:

distanceTol - simplification distance tolerance to use

Returns:

the simplified coordinate list