discrete_frechet_distance (with strategy)

Calculate the discrete Frechet distance between two geometries using the specified strategy.

Description

The free function discrete_frechet_distance calculates the discrete Frechet distance between two geometries.

Synopsis

template<typename Geometry1, typename Geometry2, typename Strategy>
auto discrete_frechet_distance(Geometry1 const & geometry1, Geometry2 const & geometry2, Strategy const & strategy)

Parameters

Type	Concept	Name	Description
Geometry1 const &	Any type fulfilling a Geometry Concept	geometry1	A model of the specified concept
Geometry2 const &	Any type fulfilling a Geometry Concept	geometry2	A model of the specified concept
Strategy const &	Any type fulfilling a Distance Strategy Concept	strategy	The strategy which will be used for point to point distance calculations

Header

Either

#include <boost/geometry.hpp>

#include <boost/geometry/algorithms/discrete_frechet_distance.hpp>

Conformance

The function discrete_frechet_distance is not defined by OGC.

	Note
	PostGIS contains an algorithm ST_FrechetDistance with similar functionality. See the PostGIS documentation.

Supported geometries

Geometries	Status
Linestring-Linestring

	Note
	The units of the distance depends on strategy. In order to change the default behavior a user has to create a strategy and pass it explicitly into the algorithm.

Available Strategies

Pythagoras (cartesian)
Haversine (spherical)
One of the geographic point to point strategies

Example

Calculate Similarity between two geometries as the discrete frechet distance between them.

#include <iostream>

#include <boost/geometry.hpp>
#include <boost/geometry/geometries/point.hpp>
#include <boost/geometry/geometries/linestring.hpp>

int main()
{
    namespace bg = boost::geometry;
    using point_type = bg::model::point<double, 2, bg::cs::geographic<bg::degree>>;
    using linestring_type = bg::model::linestring<point_type>;

    linestring_type ls1, ls2;
    bg::read_wkt("LINESTRING(0 0,1 1,1 2,2 1,2 2)", ls1);
    bg::read_wkt("LINESTRING(1 0,0 1,1 1,2 1,3 1)", ls2);

    bg::srs::spheroid<double> spheroid(6378137.0, 6356752.3142451793);
    bg::strategy::distance::geographic<> strategy(spheroid);

    double res = bg::discrete_frechet_distance(ls1, ls2, strategy);

    std::cout << "Discrete Frechet Distance: " << res << std::endl;

    return 0;
}

Output:

Discrete Frechet Distance: 156874