GeographicLib  1.21
Public Member Functions | Static Public Attributes
GeographicLib::PolarStereographic Class Reference

Polar Stereographic Projection. More...

#include <GeographicLib/PolarStereographic.hpp>

List of all members.

Public Member Functions

 PolarStereographic (real a, real f, real k0)
void SetScale (real lat, real k=real(1))
void Forward (bool northp, real lat, real lon, real &x, real &y, real &gamma, real &k) const throw ()
void Reverse (bool northp, real x, real y, real &lat, real &lon, real &gamma, real &k) const throw ()
void Forward (bool northp, real lat, real lon, real &x, real &y) const throw ()
void Reverse (bool northp, real x, real y, real &lat, real &lon) const throw ()
Inspector functions
Math::real MajorRadius () const throw ()
Math::real Flattening () const throw ()
Math::real CentralScale () const throw ()

Static Public Attributes

static const PolarStereographic UPS

Detailed Description

Polar Stereographic Projection.

Implementation taken from the report,

This is a straightforward implementation of the equations in Snyder except that Newton's method is used to invert the projection.

Example of use:

// Example of using the GeographicLib::PolarStereographic class
// $Id: 76bd97693e4f711118164cc0cde1db7f5ca70e12 $

#include <iostream>
#include <exception>
#include <string>
#include <iomanip>
#include <GeographicLib/PolarStereographic.hpp>

using namespace std;
using namespace GeographicLib;

int main() {
  try {
    PolarStereographic proj(Constants::WGS84_a(), Constants::WGS84_f(),
                            Constants::UPS_k0());
    // Alternatively:
    // const PolarStereographic& proj = PolarStereographic::UPS;
    bool northp = true;
    {
      // Sample forward calculation
      double lat = 61.2, lon = -149.9; // Anchorage
      double x, y;
      proj.Forward(northp, lat, lon, x, y);
      cout << x << " " << y << "\n";
    }
    {
      // Sample reverse calculation
      double x = -1637e3, y = 2824e3;
      double lat, lon;
      proj.Reverse(northp, x, y, lat, lon);
      cout << lat << " " << lon << "\n";
    }
  }
  catch (const exception& e) {
    cerr << "Caught exception: " << e.what() << "\n";
    return 1;
  }
  return 0;
}

Constructor & Destructor Documentation

GeographicLib::PolarStereographic::PolarStereographic ( real  a,
real  f,
real  k0 
)

Constructor for a ellipsoid with

Parameters:
[in]aequatorial radius (meters).
[in]fflattening of ellipsoid. Setting f = 0 gives a sphere. Negative f gives a prolate ellipsoid. If f > 1, set flattening to 1/f.
[in]k0central scale factor.

An exception is thrown if either of the axes of the ellipsoid is not positive a or if k0 is not positive.

Definition at line 28 of file PolarStereographic.cpp.

References GeographicLib::Math::isfinite().


Member Function Documentation

void GeographicLib::PolarStereographic::SetScale ( real  lat,
real  k = real(1) 
)

Set the scale for the projection.

Parameters:
[in]lat(degrees) assuming northp = true.
[in]kscale at latitude lat (default 1).

This allows a "latitude of true scale" to be specified. An exception is thrown if k is not positive or if lat is not in the range (-90, 90].

Definition at line 126 of file PolarStereographic.cpp.

References GeographicLib::Math::isfinite(), and Forward().

void GeographicLib::PolarStereographic::Forward ( bool  northp,
real  lat,
real  lon,
real &  x,
real &  y,
real &  gamma,
real &  k 
) const throw ()

Forward projection, from geographic to polar stereographic.

Parameters:
[in]northpthe pole which is the center of projection (true means north, false means south).
[in]latlatitude of point (degrees).
[in]lonlongitude of point (degrees).
[out]xeasting of point (meters).
[out]ynorthing of point (meters).
[out]gammameridian convergence at point (degrees).
[out]kscale of projection at point.

No false easting or northing is added. lat should be in the range (-90, 90] for northp = true and in the range [-90, 90) for northp = false; lon should be in the range [-180, 360].

Definition at line 72 of file PolarStereographic.cpp.

References GeographicLib::Math::hypot(), and GeographicLib::Math::sq().

Referenced by SetScale(), and GeographicLib::UTMUPS::Forward().

void GeographicLib::PolarStereographic::Reverse ( bool  northp,
real  x,
real  y,
real &  lat,
real &  lon,
real &  gamma,
real &  k 
) const throw ()

Reverse projection, from polar stereographic to geographic.

Parameters:
[in]northpthe pole which is the center of projection (true means north, false means south).
[in]xeasting of point (meters).
[in]ynorthing of point (meters).
[out]latlatitude of point (degrees).
[out]lonlongitude of point (degrees).
[out]gammameridian convergence at point (degrees).
[out]kscale of projection at point.

No false easting or northing is added. The value of lon returned is in the range [-180, 180).

Definition at line 95 of file PolarStereographic.cpp.

References GeographicLib::Math::hypot(), and GeographicLib::Math::sq().

Referenced by GeographicLib::UTMUPS::Reverse().

void GeographicLib::PolarStereographic::Forward ( bool  northp,
real  lat,
real  lon,
real &  x,
real &  y 
) const throw () [inline]

PolarStereographic::Forward without returning the convergence and scale.

Definition at line 121 of file PolarStereographic.hpp.

void GeographicLib::PolarStereographic::Reverse ( bool  northp,
real  x,
real  y,
real &  lat,
real &  lon 
) const throw () [inline]

PolarStereographic::Reverse without returning the convergence and scale.

Definition at line 130 of file PolarStereographic.hpp.

Math::real GeographicLib::PolarStereographic::MajorRadius ( ) const throw () [inline]
Returns:
a the equatorial radius of the ellipsoid (meters). This is the value used in the constructor.

Definition at line 143 of file PolarStereographic.hpp.

Math::real GeographicLib::PolarStereographic::Flattening ( ) const throw () [inline]
Returns:
f the flattening of the ellipsoid. This is the value used in the constructor.

Definition at line 149 of file PolarStereographic.hpp.

Math::real GeographicLib::PolarStereographic::CentralScale ( ) const throw () [inline]

The central scale for the projection. This is the value of k0 used in the constructor and is the scale at the pole unless overridden by PolarStereographic::SetScale.

Definition at line 164 of file PolarStereographic.hpp.


Member Data Documentation

A global instantiation of PolarStereographic with the WGS84 ellipsoid and the UPS scale factor. However, unlike UPS, no false easting or northing is added.

Definition at line 172 of file PolarStereographic.hpp.


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