| Home | Libraries | People | FAQ | More

##### discrete_hausdorff_distance (with strategy)

Calculate discrete Hausdorff distance between two geometries (currently works for LineString-LineString, MultiPoint-MultiPoint, Point-MultiPoint, MultiLineString-MultiLineString) using specified strategy.

###### Synopsis

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

###### Parameters

Type | Concept | Name | Description
--- | --- | --- | ---
Geometry1 const & | Any type fulfilling a Geometry Concept | geometry1 | Input geometry
Geometry2 const & | Any type fulfilling a Geometry Concept | geometry2 | Input geometry
Strategy const & | A type fulfilling a DistanceStrategy concept | strategy | Distance strategy to be used to calculate Pt-Pt distance

###### Header

Either

`#include <boost/geometry.hpp>`

Or

`#include <boost/geometry/algorithms/discrete_hausdorff_distance.hpp>`

###### Behavior

The algorithm calculate discrete hausdorff distance between two geometries.

| 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)

###### Example

Calculate Similarity between two geometries as the discrete hausdorff 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;
        typedef bg::model::point<double, 2, bg::cs::geographic<bg::degree> > point_type;
        typedef bg::model::linestring<point_type> linestring_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_hausdorff_distance(ls1, ls2, strategy);

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

        return 0;
    }

Output:

    Discrete Hausdorff Distance: 110574