| Home | Libraries | People | FAQ | More

#### strategy::buffer::geographic_point_circle

Create a circular buffer around a point, on the Earth.

###### Description

This strategy can be used as PointStrategy for the buffer algorithm. It creates a circular buffer around a point, on the Earth. It can be applied for points and multi_points.

###### Synopsis

    template<typename FormulaPolicy, typename Spheroid, typename CalculationType>
    class strategy::buffer::geographic_point_circle
    {
      // ...
    };

###### Template parameter(s)

Parameter | Default | Description
--- | --- | ---
typename FormulaPolicy | strategy::andoyer |
typename Spheroid | srs::spheroid<double> |
typename CalculationType | void |

###### Constructor(s)

Function | Description | Parameters
--- | --- | ---
    geographic_point_circle(std::size_t count = 90)
| Constructs the strategy. | std::size_t: count: number of points for the created circle (if count is smaller than 3, count is internally set to 3)

###### Header

`#include <boost/geometry/strategies/geographic/buffer_point_circle.hpp>`

###### Example

Shows how the point_circle strategy, for the Earth, can be used as a PointStrategy to create circular buffers around points

    #include <boost/geometry.hpp>
    #include <iostream>

    int main()
    {
        namespace bg = boost::geometry;

        typedef bg::model::point<double, 2, bg::cs::geographic<bg::degree> > point;

        // Declare the geographic_point_circle strategy (with 36 points)
        // Default template arguments (taking Andoyer strategy)
        bg::strategy::buffer::geographic_point_circle<> point_strategy(36);

        // Declare the distance strategy (one kilometer, around the point, on Earth)
        bg::strategy::buffer::distance_symmetric<double> distance_strategy(1000.0);

        // Declare other necessary strategies, unused for point
        bg::strategy::buffer::join_round join_strategy;
        bg::strategy::buffer::end_round end_strategy;
        bg::strategy::buffer::side_straight side_strategy;

        // Declare/fill a point on Earth, near Amsterdam
        point p;
        bg::read_wkt("POINT(4.9 52.1)", p);

        // Create the buffer of a point on the Earth
        bg::model::multi_polygon<bg::model::polygon<point> > result;
        bg::buffer(p, result,
                    distance_strategy, side_strategy,
                    join_strategy, end_strategy, point_strategy);

        std::cout << "Area: " << bg::area(result) / (1000 * 1000) << " square kilometer" << std::endl;

        return 0;
    }

Output:

    Area: 3.12542 square kilometer

###### See also

- buffer (with strategies)
- point_circle
- point_square