geos::operation::overlayng::OverlayNGRobust Class Reference

#include <OverlayNGRobust.h>

Static Public Member Functions
static std::unique_ptr< Geometry >	Intersection (const Geometry *g0, const Geometry *g1)
static std::unique_ptr< Geometry >	Union (const Geometry *g0, const Geometry *g1)
static std::unique_ptr< Geometry >	Difference (const Geometry *g0, const Geometry *g1)
static std::unique_ptr< Geometry >	SymDifference (const Geometry *g0, const Geometry *g1)
static std::unique_ptr< Geometry >	Union (const Geometry *a)
static std::unique_ptr< Geometry >	Overlay (const Geometry *geom0, const Geometry *geom1, int opCode)
static std::unique_ptr< Geometry >	overlaySnapTries (const Geometry *geom0, const Geometry *geom1, int opCode)
static double	snapTolerance (const Geometry *geom0, const Geometry *geom1)

Detailed Description

Performs an overlay operation, increasing robustness by using a series of increasingly aggressive (and slower) noding strategies.

The noding strategies used are:

• A simple, fast noder using FLOATING precision.
• A noding::snap::SnappingNoder using an automatically-determined snap tolerance
• First snapping each geometry to itself, and then overlaying them using a SnappingNoder.
• The above two strategies are repeated with increasing snap tolerance, up to a limit.

If the above heuristics still fail to compute a valid overlay, the original util::TopologyException is thrown.

This algorithm relies on each overlay operation execution throwing a util::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 noding::ValidatingNoder in order to check the results of using a floating noder.

Author

Martin Davis

Member Function Documentation

snapTolerance()

static double geos::operation::overlayng::OverlayNGRobust::snapTolerance ( const Geometry *  geom0, const Geometry *  geom1  )

static

Computes a heuristic snap tolerance distance for overlaying a pair of geometries using a noding::snap::SnappingNoder.

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The documentation for this class was generated from the following file:

• OverlayNGRobust.h