geos::algorithm::distance::DiscreteFrechetDistance Class Reference

The Fréchet distance is a measure of similarity between curves. Thus, it can be used like the Hausdorff distance. More...

#include <DiscreteFrechetDistance.h>

Classes
class	MatrixStorage
class	RectMatrix
class	CsrMatrix
class	HashMapMatrix

Public Member Functions
	DiscreteFrechetDistance (const geom::Geometry &geom0, const geom::Geometry &geom1)
std::array< geom::CoordinateXY, 2 >	getCoordinates ()
void	setDensifyFraction (double dFrac)

Static Public Member Functions
static double	distance (const geom::Geometry &geom0, const geom::Geometry &geom1)
static double	distance (const geom::Geometry &geom0, const geom::Geometry &geom1, double densityFrac)

Detailed Description

The Fréchet distance is a measure of similarity between curves. Thus, it can be used like the Hausdorff distance.

An analogy for the Fréchet distance taken from Computing Discrete Fréchet Distance

A man is walking a dog on a leash: the man can move on one curve, the dog on the other; both may vary their speed, but backtracking is not allowed.

Its metric is better than the Hausdorff distance because it takes the directions of the curves into account. It is possible that two curves have a small Hausdorff but a large Fréchet distance.

This implementation is base on the following optimized Fréchet distance algorithm: Thomas Devogele, Maxence Esnault, Laurent Etienne. Distance discrète de Fréchet optimisée. Spatial Analysis and Geomatics (SAGEO), Nov 2016, Nice, France. hal-02110055

Several matrix storage implementations are provided

• Fréchet distance
• Computing Discrete Fréchet Distance
• Distance discrète de Fréchet optimisée
• Fast Discrete Fréchet Distance

See also

DiscreteHausdorffDistance

Constructor & Destructor Documentation

DiscreteFrechetDistance()

geos::algorithm::distance::DiscreteFrechetDistance::DiscreteFrechetDistance ( const geom::Geometry & geom0, const geom::Geometry & geom1 )

inline

Creates an instance of this class using the provided geometries.

Parameters

geom0	a geometry
geom1	a geometry

Member Function Documentation

distance() [1/2]

double geos::algorithm::distance::DiscreteFrechetDistance::distance ( const geom::Geometry & geom0, const geom::Geometry & geom1 )

static

Computes the Discrete Fréchet Distance between two Geometrys using a Cartesian distance computation function.

Parameters

geom0	the 1st geometry
geom1	the 2nd geometry

Returns

the cartesian distance between geom0 and geom1

Referenced by getCoordinates().

distance() [2/2]

double geos::algorithm::distance::DiscreteFrechetDistance::distance ( const geom::Geometry & geom0, const geom::Geometry & geom1, double densityFrac )

static

Computes the Discrete Fréchet Distance between two Geometrys using a Cartesian distance computation function.

Parameters

geom0	the 1st geometry
geom1	the 2nd geometry
densityFrac	the fraction of edge length to target when densifying edges

Returns

the cartesian distance between geom0 and geom1

getCoordinates()

std::array< geom::CoordinateXY, 2 > geos::algorithm::distance::DiscreteFrechetDistance::getCoordinates

(

)

Gets the pair of geom::Coordinates at which the distance is obtained.

Returns

the pair of Coordinates at which the distance is obtained

References distance().

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

• DiscreteFrechetDistance.h