Public Member Functions | Private Types | Private Attributes | List of all members
GeographicLib::AzimuthalEquidistant Class Reference

Azimuthal equidistant projection. More...

#include <AzimuthalEquidistant.hpp>

Public Member Functions

 AzimuthalEquidistant (const Geodesic &earth=Geodesic::WGS84())
 
void Forward (real lat0, real lon0, real lat, real lon, real &x, real &y, real &azi, real &rk) const
 
void Forward (real lat0, real lon0, real lat, real lon, real &x, real &y) const
 
void Reverse (real lat0, real lon0, real x, real y, real &lat, real &lon, real &azi, real &rk) const
 
void Reverse (real lat0, real lon0, real x, real y, real &lat, real &lon) const
 
Inspector functions
Math::real MajorRadius () const
 
Math::real Flattening () const
 

Private Types

typedef Math::real real
 

Private Attributes

Geodesic _earth
 
real eps_
 

Detailed Description

Azimuthal equidistant projection.

Azimuthal equidistant projection centered at an arbitrary position on the ellipsoid. For a point in projected space (x, y), the geodesic distance from the center position is hypot(x, y) and the azimuth of the geodesic from the center point is atan2(x, y). The Forward and Reverse methods also return the azimuth azi of the geodesic at (x, y) and reciprocal scale rk in the azimuthal direction which, together with the basic properties of the projection, serve to specify completely the local affine transformation between geographic and projected coordinates.

The conversions all take place using a Geodesic object (by default Geodesic::WGS84()). For more information on geodesics see geodesic.

Example of use:

// Example of using the GeographicLib::AzimuthalEquidistant class
#include <iostream>
#include <exception>
using namespace std;
using namespace GeographicLib;
int main() {
try {
// Alternatively: const Geodesic& geod = Geodesic::WGS84();
const double lat0 = 48 + 50/60.0, lon0 = 2 + 20/60.0; // Paris
{
// Sample forward calculation
double lat = 50.9, lon = 1.8; // Calais
double x, y;
proj.Forward(lat0, lon0, lat, lon, x, y);
cout << x << " " << y << "\n";
}
{
// Sample reverse calculation
double x = -38e3, y = 230e3;
double lat, lon;
proj.Reverse(lat0, lon0, x, y, lat, lon);
cout << lat << " " << lon << "\n";
}
}
catch (const exception& e) {
cerr << "Caught exception: " << e.what() << "\n";
return 1;
}
}

GeodesicProj is a command-line utility providing access to the functionality of AzimuthalEquidistant, Gnomonic, and CassiniSoldner.

Definition at line 42 of file AzimuthalEquidistant.hpp.

Member Typedef Documentation

◆ real

Definition at line 44 of file AzimuthalEquidistant.hpp.

Constructor & Destructor Documentation

◆ AzimuthalEquidistant()

GeographicLib::AzimuthalEquidistant::AzimuthalEquidistant ( const Geodesic earth = Geodesic::WGS84())
explicit

Constructor for AzimuthalEquidistant.

Parameters
[in]earththe Geodesic object to use for geodesic calculations. By default this uses the WGS84 ellipsoid.

Definition at line 16 of file src/AzimuthalEquidistant.cpp.

Member Function Documentation

◆ Flattening()

Math::real GeographicLib::AzimuthalEquidistant::Flattening ( ) const
inline
Returns
f the flattening of the ellipsoid. This is the value inherited from the Geodesic object used in the constructor.

Definition at line 132 of file AzimuthalEquidistant.hpp.

◆ Forward() [1/2]

void GeographicLib::AzimuthalEquidistant::Forward ( real  lat0,
real  lon0,
real  lat,
real  lon,
real x,
real y,
real azi,
real rk 
) const

Forward projection, from geographic to azimuthal equidistant.

Parameters
[in]lat0latitude of center point of projection (degrees).
[in]lon0longitude of center point of projection (degrees).
[in]latlatitude of point (degrees).
[in]lonlongitude of point (degrees).
[out]xeasting of point (meters).
[out]ynorthing of point (meters).
[out]aziazimuth of geodesic at point (degrees).
[out]rkreciprocal of azimuthal scale at point.

lat0 and lat should be in the range [−90°, 90°]. The scale of the projection is 1 in the "radial" direction, azi clockwise from true north, and is 1/rk in the direction perpendicular to this. A call to Forward followed by a call to Reverse will return the original (lat, lon) (to within roundoff).

Definition at line 20 of file src/AzimuthalEquidistant.cpp.

◆ Forward() [2/2]

void GeographicLib::AzimuthalEquidistant::Forward ( real  lat0,
real  lon0,
real  lat,
real  lon,
real x,
real y 
) const
inline

AzimuthalEquidistant::Forward without returning the azimuth and scale.

Definition at line 104 of file AzimuthalEquidistant.hpp.

◆ MajorRadius()

Math::real GeographicLib::AzimuthalEquidistant::MajorRadius ( ) const
inline
Returns
a the equatorial radius of the ellipsoid (meters). This is the value inherited from the Geodesic object used in the constructor.

Definition at line 126 of file AzimuthalEquidistant.hpp.

◆ Reverse() [1/2]

void GeographicLib::AzimuthalEquidistant::Reverse ( real  lat0,
real  lon0,
real  x,
real  y,
real lat,
real lon,
real azi,
real rk 
) const

Reverse projection, from azimuthal equidistant to geographic.

Parameters
[in]lat0latitude of center point of projection (degrees).
[in]lon0longitude of center point of projection (degrees).
[in]xeasting of point (meters).
[in]ynorthing of point (meters).
[out]latlatitude of point (degrees).
[out]lonlongitude of point (degrees).
[out]aziazimuth of geodesic at point (degrees).
[out]rkreciprocal of azimuthal scale at point.

lat0 should be in the range [−90°, 90°]. lat will be in the range [−90°, 90°] and lon will be in the range [−180°, 180°]. The scale of the projection is 1 in the "radial" direction, azi clockwise from true north, and is 1/rk in the direction perpendicular to this. A call to Reverse followed by a call to Forward will return the original (x, y) (to roundoff) only if the geodesic to (x, y) is a shortest path.

Definition at line 30 of file src/AzimuthalEquidistant.cpp.

◆ Reverse() [2/2]

void GeographicLib::AzimuthalEquidistant::Reverse ( real  lat0,
real  lon0,
real  x,
real  y,
real lat,
real lon 
) const
inline

AzimuthalEquidistant::Reverse without returning the azimuth and scale.

Definition at line 113 of file AzimuthalEquidistant.hpp.

Member Data Documentation

◆ _earth

Geodesic GeographicLib::AzimuthalEquidistant::_earth
private

Definition at line 46 of file AzimuthalEquidistant.hpp.

◆ eps_

real GeographicLib::AzimuthalEquidistant::eps_
private

Definition at line 45 of file AzimuthalEquidistant.hpp.


The documentation for this class was generated from the following files:


gtsam
Author(s):
autogenerated on Tue Jul 4 2023 02:46:12