simplify

Simplify a geometry.

Synopsis

template<typename Geometry, typename GeometryOut, typename Distance>
void simplify(Geometry const & geometry, GeometryOut & out, Distance const & max_distance)

Parameters

Type	Concept	Name	Description
Geometry const &	Any type fulfilling a Geometry Concept	geometry	input geometry, to be simplified
GeometryOut &	The output geometry	out	output geometry, simplified version of the input geometry
Distance const &	numerical type (int, double, ttmath, ...)	max_distance	distance (in units of input coordinates) of a vertex to other segments to be removed

Header

Either

#include <boost/geometry.hpp>

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

Conformance

The function simplify is not defined by OGC.

	Note
	PostGIS contains an algorithm with the same name and the same functionality. See the PostGIS documentation.

	Note
	SQL Server contains an algorithm Reduce() with the same functionality. See the MSDN documentation.

Behavior

Simplification is done using Douglas-Peucker (if the default strategy is used).

	Note
	Geometries might become invalid by using simplify. The simplification process might create self-intersections.

Examples

Example showing how to simplify a linestring

#include <iostream>

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


#include <boost/assign.hpp>

using namespace boost::assign;


int main()
{
    typedef boost::geometry::model::d2::point_xy<double> xy;

    boost::geometry::model::linestring<xy> line;
    line += xy(1.1, 1.1), xy(2.5, 2.1), xy(3.1, 3.1), xy(4.9, 1.1), xy(3.1, 1.9); 

    // Simplify it, using distance of 0.5 units
    boost::geometry::model::linestring<xy> simplified;
    boost::geometry::simplify(line, simplified, 0.5);
    std::cout
        << "  original: " << boost::geometry::dsv(line) << std::endl
        << "simplified: " << boost::geometry::dsv(simplified) << std::endl;


    return 0;
}

	For this example we use Boost.Assign to add points
	With Boost.Assign

Output:

original: ((1.1, 1.1), (2.5, 2.1), (3.1, 3.1), (4.9, 1.1), (3.1, 1.9))
simplified: ((1.1, 1.1), (3.1, 3.1), (4.9, 1.1), (3.1, 1.9))

Image(s)

svg_simplify_country