centroid (with strategy)

| Home | Libraries | People | FAQ | More

##### centroid (with strategy)

Calculates the centroid of a geometry using the specified strategy.

###### Description

The free function centroid calculates the geometric center (or: center of mass) of a geometry. Reasons to specify a strategy include: use another coordinate system for calculations; construct the strategy beforehand (e.g. with the radius of the Earth); select a strategy when there are more than one available for a calculation.

###### Synopsis

    template<typename Geometry, typename Point, typename Strategy>
    void centroid(Geometry const & geometry, Point & c, Strategy const & strategy)

###### Parameters

Type | Concept | Name | Description
--- | --- | --- | ---
Geometry const & | Any type fulfilling a Geometry Concept | geometry | A model of the specified concept
Point & | Any type fulfilling a Point Concept | c | A model of the specified Point Concept which is set to the centroid
Strategy const & | Any type fulfilling a Centroid Strategy Concept | strategy | The strategy which will be used for centroid calculations

###### Header

Either

`#include <boost/geometry.hpp>`

Or

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

###### Conformance

The function centroid implements function Centroid from the OGC Simple Feature Specification.

###### Behavior

Case | Behavior
--- | ---
Point | Returns the point itself as the centroid
Multi Point | Calculates centroid (based on average)
linear (e.g. linestring) | Calculates centroid (based on weighted length)
areal (e.g. polygon) | Calculates centroid
Empty (e.g. polygon without points) | Throws a centroid_exception
Cartesian | Implemented
Spherical | Calculates the centroid as if based on Cartesian coordinates

###### Supported geometries

| 2D | 3D
--- | --- | ---
Point |  |
Segment |  |
Box |  |
Linestring |  |
Ring |  |
Polygon |  |
MultiPoint |  |
MultiLinestring |  |
MultiPolygon |  |

###### Complexity

Linear

###### Available Strategies

- Bashein Detmer (cartesian)