Package org.locationtech.jts.operation.overlayng

Class OverlayNGRobust

java.lang.Object

org.locationtech.jts.operation.overlayng.OverlayNGRobust

public class OverlayNGRobust
extends java.lang.Object

Performs an overlay operation using OverlayNG, providing full robustness by using a series of increasingly robust (but slower) noding strategies.

The noding strategies used are:

1. A simple, fast noder using FLOATING precision.
2. A SnappingNoder using an automatically-determined snap tolerance
3. First snapping each geometry to itself, and then overlaying them using a SnappingNoder.
4. The above two strategies are repeated with increasing snap tolerance, up to a limit.
5. Finally a SnapRoundngNoder is used with a automatically-determined scale factor intended to preserve input precision while still preventing robustness problems.

If all of the above attempts fail to compute a valid overlay, the original TopologyException is thrown. In practice this is extremely unlikely to occur.

This algorithm relies on each overlay operation execution throwing a TopologyException if it is unable to compute the overlay correctly. Generally this occurs because the noding phase does not produce a valid noding. This requires the use of a ValidatingNoder in order to check the results of using a floating noder.

Author:

Martin Davis

See Also:

OverlayNG

Constructor Summary

Constructors

Constructor	Description
OverlayNGRobust()

Method Summary

Modifier and Type	Method	Description
static Geometry	overlay(Geometry geom0, Geometry geom1, int opCode)	Overlay two geometries, using heuristics to ensure computation completes correctly.
static Geometry	union(Geometry geom)	Computes unary union using robust computation.

Methods inherited from class java.lang.Object

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

Constructor Detail

OverlayNGRobust

public OverlayNGRobust()

Method Detail

union

public static Geometry union(Geometry geom)

Computes unary union using robust computation.

Parameters:

geom - the geometry to union

Returns:

the union result

See Also:

UnaryUnionOp

overlay

public static Geometry overlay(Geometry geom0,
                               Geometry geom1,
                               int opCode)

Overlay two geometries, using heuristics to ensure computation completes correctly. In practice the heuristics are observed to be fully correct.

Parameters:

geom0 - a geometry

geom1 - a geometry

opCode - the overlay operation code (from OverlayNG

Returns:

the overlay result geometry

See Also:

OverlayNG