.NET wrapper for GeographicLib::Geocentric. More...

#include <Geocentric.h>

Public Member Functions
void	Forward (double lat, double lon, double h, [System::Runtime::InteropServices::Out] double%X, [System::Runtime::InteropServices::Out] double%Y, [System::Runtime::InteropServices::Out] double%Z)

void	Forward (double lat, double lon, double h, [System::Runtime::InteropServices::Out] double%X, [System::Runtime::InteropServices::Out] double%Y, [System::Runtime::InteropServices::Out] double%Z, [System::Runtime::InteropServices::Out] array< double, 2 >^%M)

	Geocentric (double a, double f)

	Geocentric ()

	Geocentric (const GeographicLib::Geocentric &g)

void	Reverse (double X, double Y, double Z, [System::Runtime::InteropServices::Out] double%lat, [System::Runtime::InteropServices::Out] double%lon, [System::Runtime::InteropServices::Out] double%h)

void	Reverse (double X, double Y, double Z, [System::Runtime::InteropServices::Out] double%lat, [System::Runtime::InteropServices::Out] double%lon, [System::Runtime::InteropServices::Out] double%h, [System::Runtime::InteropServices::Out] array< double, 2 >^%M)

	~Geocentric ()

Private Member Functions
	!Geocentric ()

Private Attributes
const GeographicLib::Geocentric *	m_pGeocentric

Inspector functions
property double	MajorRadius { double get()

property double	Flattening { double get()

System::IntPtr	GetUnmanaged ()

Detailed Description

.NET wrapper for GeographicLib::Geocentric.

This class allows .NET applications to access GeographicLib::Geocentric.

Convert between geodetic coordinates latitude = lat, longitude = lon, height = h (measured vertically from the surface of the ellipsoid) to geocentric coordinates (X, Y, Z). The origin of geocentric coordinates is at the center of the earth. The Z axis goes thru the north pole, lat = 90°. The X axis goes thru lat = 0, lon = 0. Geocentric coordinates are also known as earth centered, earth fixed (ECEF) coordinates.

The conversion from geographic to geocentric coordinates is straightforward. For the reverse transformation we use

H. Vermeille, Direct transformation from geocentric coordinates to geodetic coordinates, J. Geodesy 76, 451–454 (2002).

Several changes have been made to ensure that the method returns accurate results for all finite inputs (even if h is infinite). The changes are described in Appendix B of

C. F. F. Karney, Geodesics on an ellipsoid of revolution, Feb. 2011; preprint arxiv:1102.1215v1.

See geocentric for more information.

The errors in these routines are close to round-off. Specifically, for points within 5000 km of the surface of the ellipsoid (either inside or outside the ellipsoid), the error is bounded by 7 nm (7 nanometers) for the WGS84 ellipsoid. See geocentric for further information on the errors.

C# Example:

using System;
using NETGeographicLib;
namespace example_Geocentric
{
    class Program
    {
        static void Main(string[] args)
        {
            try {
                Geocentric earth = new Geocentric( Constants.WGS84.MajorRadius,
                                                   Constants.WGS84.Flattening);
                // Alternatively: Geocentric earth = new Geocentric();
                {
                    // Sample forward calculation
                    double lat = 27.99, lon = 86.93, h = 8820; // Mt Everest
                    double X, Y, Z;
                    earth.Forward(lat, lon, h, out X, out Y, out Z);
                    Console.WriteLine( String.Format( "{0} {1} {2}",
                        Math.Floor(X / 1000 + 0.5),
                        Math.Floor(Y / 1000 + 0.5),
                        Math.Floor(Z / 1000 + 0.5) ) );
                }
                {
                    // Sample reverse calculation
                    double X = 302e3, Y = 5636e3, Z = 2980e3;
                    double lat, lon, h;
                    earth.Reverse(X, Y, Z, out lat, out lon, out h);
                    Console.WriteLine(String.Format("{0} {1} {2}", lat, lon, h));
                }
            }
            catch (GeographicErr e) {
                Console.WriteLine( String.Format( "Caught exception: {0}", e.Message ) );
            }
        }
    }
}

Managed C++ Example:

// Example of using the GeographicLib::Geocentric class
#include <iostream>
#include <exception>
#include <cmath>
#include <GeographicLib/Geocentric.hpp>
using namespace std;
using namespace GeographicLib;
int main() {
  try {
    Geocentric earth(Constants::WGS84_a(), Constants::WGS84_f());
    // Alternatively: const Geocentric& earth = Geocentric::WGS84();
    {
      // Sample forward calculation
      double lat = 27.99, lon = 86.93, h = 8820; // Mt Everest
      double X, Y, Z;
      earth.Forward(lat, lon, h, X, Y, Z);
      cout << floor(X / 1000 + 0.5) << " "
           << floor(Y / 1000 + 0.5) << " "
           << floor(Z / 1000 + 0.5) << "\n";
    }
    {
      // Sample reverse calculation
      double X = 302e3, Y = 5636e3, Z = 2980e3;
      double lat, lon, h;
      earth.Reverse(X, Y, Z, lat, lon, h);
      cout << lat << " " << lon << " " << h << "\n";
    }
  }
  catch (const exception& e) {
    cerr << "Caught exception: " << e.what() << "\n";
    return 1;
  }
}

Visual Basic Example:

Imports NETGeographicLib
Module example_Geocentric
    Sub Main()
        Try
            Dim earth As Geocentric = New Geocentric(Constants.WGS84.MajorRadius,
                                                     Constants.WGS84.Flattening)
            ' Alternatively: Geocentric earth = new Geocentric();
            ' Sample forward calculation
            Dim lat As Double = 27.99, lon = 86.93, h = 8820 ' Mt Everest
            Dim X, Y, Z As Double
            earth.Forward(lat, lon, h, X, Y, Z)
            Console.WriteLine(String.Format("{0} {1} {2}",
                Math.Floor(X / 1000 + 0.5),
                Math.Floor(Y / 1000 + 0.5),
                Math.Floor(Z / 1000 + 0.5)))
            ' Sample reverse calculation
            X = 302000.0 : Y = 5636000.0 : Z = 2980000.0
            earth.Reverse(X, Y, Z, lat, lon, h)
            Console.WriteLine(String.Format("{0} {1} {2}", lat, lon, h))
        Catch ex As GeographicErr
            Console.WriteLine(String.Format("Caught exception: {0}", ex.Message))
        End Try
    End Sub
End Module

INTERFACE DIFFERENCES:
A default constructor is provided that assumes WGS84 parameters.

The MajorRadius and Flattening functions are implemented as properties.

The Forward and Reverse functions return rotation matrices as 2D, 3 × 3 arrays rather than vectors.

Definition at line 68 of file Geocentric.h.

Constructor & Destructor Documentation

Geocentric::!Geocentric ( )

private

Definition at line 21 of file dotnet/NETGeographicLib/Geocentric.cpp.

Geocentric::Geocentric	(	double	a,
		double	f
	)

Constructor for a ellipsoid with

Parameters

[in]	a	equatorial radius (meters).
[in]	f	flattening of ellipsoid. Setting f = 0 gives a sphere. Negative f gives a prolate ellipsoid.

Exceptions

GeographicErr if a or (1 − f ) a is not positive.

Definition at line 45 of file dotnet/NETGeographicLib/Geocentric.cpp.

Geocentric::Geocentric ( void )

A default constructor which assumes WGS84.

Definition at line 31 of file dotnet/NETGeographicLib/Geocentric.cpp.

Geocentric::Geocentric ( const GeographicLib::Geocentric & g )

A constructor that is initialized from an unmanaged GeographicLib::Geocentric. For internal use only.

Parameters

[in] g An existing GeographicLib::Geocentric.

Definition at line 62 of file dotnet/NETGeographicLib/Geocentric.cpp.

NETGeographicLib::Geocentric::~Geocentric ( )

inline

The destructor calls the finalizer.

Definition at line 103 of file Geocentric.h.

Member Function Documentation

void Geocentric::Forward	(	double	lat,
		double	lon,
		double	h,
		[System::Runtime::InteropServices::Out] double%	X,
		[System::Runtime::InteropServices::Out] double%	Y,
		[System::Runtime::InteropServices::Out] double%	Z
	)

Convert from geodetic to geocentric coordinates.

Parameters

[in]	lat	latitude of point (degrees).
[in]	lon	longitude of point (degrees).
[in]	h	height of point above the ellipsoid (meters).
[out]	X	geocentric coordinate (meters).
[out]	Y	geocentric coordinate (meters).
[out]	Z	geocentric coordinate (meters).

lat should be in the range [−90°, 90°].

Definition at line 75 of file dotnet/NETGeographicLib/Geocentric.cpp.

void Geocentric::Forward	(	double	lat,
		double	lon,
		double	h,
		[System::Runtime::InteropServices::Out] double%	X,
		[System::Runtime::InteropServices::Out] double%	Y,
		[System::Runtime::InteropServices::Out] double%	Z,
		[System::Runtime::InteropServices::Out] array< double, 2 >^%	M
	)

Convert from geodetic to geocentric coordinates and return rotation matrix.

Parameters

[in]	lat	latitude of point (degrees).
[in]	lon	longitude of point (degrees).
[in]	h	height of point above the ellipsoid (meters).
[out]	X	geocentric coordinate (meters).
[out]	Y	geocentric coordinate (meters).
[out]	Z	geocentric coordinate (meters).
[out]	M	a 3 × 3 rotation matrix.

Let v be a unit vector located at (lat, lon, h). We can express v as column vectors in one of two ways

in east, north, up coordinates (where the components are relative to a local coordinate system at (lat, lon, h)); call this representation v1.
in geocentric X, Y, Z coordinates; call this representation v0.

Then we have v0 = M ⋅ v1.

Definition at line 88 of file dotnet/NETGeographicLib/Geocentric.cpp.

System::IntPtr Geocentric::GetUnmanaged ( )

Returns: a pointer to the unmanaged GeographicLib::Geocentric.

Definition at line 139 of file dotnet/NETGeographicLib/Geocentric.cpp.

void Geocentric::Reverse	(	double	X,
		double	Y,
		double	Z,
		[System::Runtime::InteropServices::Out] double%	lat,
		[System::Runtime::InteropServices::Out] double%	lon,
		[System::Runtime::InteropServices::Out] double%	h
	)

Convert from geocentric to geodetic to coordinates.

Parameters

[in]	X	geocentric coordinate (meters).
[in]	Y	geocentric coordinate (meters).
[in]	Z	geocentric coordinate (meters).
[out]	lat	latitude of point (degrees).
[out]	lon	longitude of point (degrees).
[out]	h	height of point above the ellipsoid (meters).

In general there are multiple solutions and the result which maximizes h is returned. If there are still multiple solutions with different latitudes (applies only if Z = 0), then the solution with lat > 0 is returned. If there are still multiple solutions with different longitudes (applies only if X = Y = 0) then lon = 0 is returned. The value of h returned satisfies h ≥ − a (1 − e²) / sqrt(1 − e² sin²lat). The value of lon returned is in the range [−180°, 180°).

Definition at line 107 of file dotnet/NETGeographicLib/Geocentric.cpp.

void Geocentric::Reverse	(	double	X,
		double	Y,
		double	Z,
		[System::Runtime::InteropServices::Out] double%	lat,
		[System::Runtime::InteropServices::Out] double%	lon,
		[System::Runtime::InteropServices::Out] double%	h,
		[System::Runtime::InteropServices::Out] array< double, 2 >^%	M
	)

Convert from geocentric to geodetic to coordinates.

Parameters

[in]	X	geocentric coordinate (meters).
[in]	Y	geocentric coordinate (meters).
[in]	Z	geocentric coordinate (meters).
[out]	lat	latitude of point (degrees).
[out]	lon	longitude of point (degrees).
[out]	h	height of point above the ellipsoid (meters).
[out]	M	a 3 × 3 rotation matrix.

Let v be a unit vector located at (lat, lon, h). We can express v as column vectors in one of two ways

in east, north, up coordinates (where the components are relative to a local coordinate system at (lat, lon, h)); call this representation v1.
in geocentric X, Y, Z coordinates; call this representation v0.

Then we have v1 = M^T ⋅ v0, where M^T is the transpose of M.

Definition at line 120 of file dotnet/NETGeographicLib/Geocentric.cpp.

Member Data Documentation

property double NETGeographicLib::Geocentric::Flattening { double get()

Returns: f the flattening of the ellipsoid. This is the value used in the constructor.

Definition at line 222 of file Geocentric.h.

const GeographicLib::Geocentric* NETGeographicLib::Geocentric::m_pGeocentric

private

Definition at line 72 of file Geocentric.h.

property double NETGeographicLib::Geocentric::MajorRadius { double get()

Returns: a the equatorial radius of the ellipsoid (meters). This is the value used in the constructor.

Definition at line 216 of file Geocentric.h.

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

Public Member Functions

Private Member Functions

Private Attributes

Inspector functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation