NETGeographicLib::TransverseMercator Class Reference

.NET wrapper for GeographicLib::TransverseMercator. More...

#include <NETGeographicLib/TransverseMercator.h>

List of all members.

Public Member Functions

 TransverseMercator (double a, double f, double k0)
 TransverseMercator ()
 ~TransverseMercator ()
void Forward (double lon0, double lat, double lon,[System::Runtime::InteropServices::Out] double% x,[System::Runtime::InteropServices::Out] double% y,[System::Runtime::InteropServices::Out] double% gamma,[System::Runtime::InteropServices::Out] double% k)
void Reverse (double lon0, double x, double y,[System::Runtime::InteropServices::Out] double% lat,[System::Runtime::InteropServices::Out] double% lon,[System::Runtime::InteropServices::Out] double% gamma,[System::Runtime::InteropServices::Out] double% k)
void Forward (double lon0, double lat, double lon,[System::Runtime::InteropServices::Out] double% x,[System::Runtime::InteropServices::Out] double% y)
void Reverse (double lon0, double x, double y,[System::Runtime::InteropServices::Out] double% lat,[System::Runtime::InteropServices::Out] double% lon)

Properties

Inspector functions



double MajorRadius [get]
double Flattening [get]
double CentralScale [get]

Detailed Description

.NET wrapper for GeographicLib::TransverseMercator.

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

This uses Krüger's method which evaluates the projection and its inverse in terms of a series. See

Krüger's method has been extended from 4th to 6th order. The maximum error is 5 nm (5 nanometers), ground distance, for all positions within 35 degrees of the central meridian. The error in the convergence is 2 1015" and the relative error in the scale is 6 1012%%. See Sec. 4 of arXiv:1002.1417 for details. The speed penalty in going to 6th order is only about 1%. TransverseMercatorExact is an alternative implementation of the projection using exact formulas which yield accurate (to 8 nm) results over the entire ellipsoid.

The ellipsoid parameters and the central scale are set in the constructor. The central meridian (which is a trivial shift of the longitude) is specified as the lon0 argument of the TransverseMercator::Forward and TransverseMercator::Reverse functions. The latitude of origin is taken to be the equator. There is no provision in this class for specifying a false easting or false northing or a different latitude of origin. However these are can be simply included by the calling function. For example, the UTMUPS class applies the false easting and false northing for the UTM projections. A more complicated example is the British National Grid (EPSG:7405) which requires the use of a latitude of origin. This is implemented by the GeographicLib::OSGB class.

See GeographicLib::TransverseMercator.cpp for more information on the implementation.

See Transverse Mercator projection for a discussion of this projection.

C# Example:

using System;
using NETGeographicLib;

namespace example_TransverseMercator
{
    class Program
    {
        static void Main(string[] args)
        {
            try {
                TransverseMercator proj = new TransverseMercator(); // WGS84
                double lon0 = -75;          // Central meridian for UTM zone 18
                {
                    // Sample forward calculation
                    double lat = 40.3, lon = -74.7; // Princeton, NJ
                    double x, y;
                    proj.Forward(lon0, lat, lon, out x, out y);
                    Console.WriteLine(String.Format("{0} {1}", x, y));
                }
                {
                    // Sample reverse calculation
                    double x = 25e3, y = 4461e3;
                    double lat, lon;
                    proj.Reverse(lon0, x, y, out lat, out lon);
                    Console.WriteLine(String.Format("{0} {1}", lat, lon));
                }
            }
            catch (GeographicErr e) {
                Console.WriteLine(String.Format("Caught exception: {0}", e.Message));
            }
        }
    }
}

Managed C++ Example:

using namespace System;
using namespace NETGeographicLib;

int main(array<System::String ^> ^/*args*/)
{
    try {
        TransverseMercator^ proj = gcnew TransverseMercator(); // WGS84
        double lon0 = -75;          // Central meridian for UTM zone 18
        {
            // Sample forward calculation
            double lat = 40.3, lon = -74.7; // Princeton, NJ
            double x, y;
            proj->Forward(lon0, lat, lon, x, y);
            Console::WriteLine(String::Format("{0} {1}", x, y));
        }
        {
            // Sample reverse calculation
            double x = 25e3, y = 4461e3;
            double lat, lon;
            proj->Reverse(lon0, x, y, lat, lon);
            Console::WriteLine(String::Format("{0} {1}", lat, lon));
        }
    }
    catch (GeographicErr^ e) {
        Console::WriteLine(String::Format("Caught exception: {0}", e->Message));
        return -1;
    }
    return 0;
}

Visual Basic Example:

Imports NETGeographicLib

Module example_TransverseMercator
    Sub Main()
        Try
            Dim proj As TransverseMercator = New TransverseMercator() ' WGS84
            Dim lon0 As Double = -75          ' Central meridian for UTM zone 18
            ' Sample forward calculation
            Dim lat As Double = 40.3, lon = -74.7 ' Princeton, NJ
            Dim x, y As Double
            proj.Forward(lon0, lat, lon, x, y)
            Console.WriteLine(String.Format("{0} {1}", x, y))
            ' Sample reverse calculation
            x = 25000.0 : y = 4461000.0
            proj.Reverse(lon0, x, y, lat, lon)
            Console.WriteLine(String.Format("{0} {1}", lat, lon))
        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 and a UTM scale factor.

The MajorRadius, Flattening, and CentralScale functions are implemented as properties.

Definition at line 77 of file TransverseMercator.h.


Constructor & Destructor Documentation

NETGeographicLib::TransverseMercator::TransverseMercator ( double  a,
double  f,
double  k0 
)

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. If f > 1, set flattening to 1/f.
[in] k0 central scale factor.
Exceptions:
GeographicErr if a, (1 f ) a, or k0 is not positive.
NETGeographicLib::TransverseMercator::TransverseMercator (  ) 

The default constructor assumes a WGS84 ellipsoid and a UTM scale factor.

Referenced by ~TransverseMercator().

NETGeographicLib::TransverseMercator::~TransverseMercator (  )  [inline]

The destructor calls the finalizer.

Definition at line 107 of file TransverseMercator.h.

References TransverseMercator().


Member Function Documentation

void NETGeographicLib::TransverseMercator::Forward ( double  lon0,
double  lat,
double  lon,
[System::Runtime::InteropServices::Out] double%   x,
[System::Runtime::InteropServices::Out] double%   y,
[System::Runtime::InteropServices::Out] double%   gamma,
[System::Runtime::InteropServices::Out] double%   k 
)

Forward projection, from geographic to transverse Mercator.

Parameters:
[in] lon0 central meridian of the projection (degrees).
[in] lat latitude of point (degrees).
[in] lon longitude of point (degrees).
[out] x easting of point (meters).
[out] y northing of point (meters).
[out] gamma meridian convergence at point (degrees).
[out] k scale of projection at point.

No false easting or northing is added. lat should be in the range [90, 90]; lon and lon0 should be in the range [540, 540).

void NETGeographicLib::TransverseMercator::Reverse ( double  lon0,
double  x,
double  y,
[System::Runtime::InteropServices::Out] double%   lat,
[System::Runtime::InteropServices::Out] double%   lon,
[System::Runtime::InteropServices::Out] double%   gamma,
[System::Runtime::InteropServices::Out] double%   k 
)

Reverse projection, from transverse Mercator to geographic.

Parameters:
[in] lon0 central meridian of the projection (degrees).
[in] x easting of point (meters).
[in] y northing of point (meters).
[out] lat latitude of point (degrees).
[out] lon longitude of point (degrees).
[out] gamma meridian convergence at point (degrees).
[out] k scale of projection at point.

No false easting or northing is added. lon0 should be in the range [540, 540). The value of lon returned is in the range [180, 180).

void NETGeographicLib::TransverseMercator::Forward ( double  lon0,
double  lat,
double  lon,
[System::Runtime::InteropServices::Out] double%   x,
[System::Runtime::InteropServices::Out] double%   y 
)

TransverseMercator::Forward without returning the convergence and scale.

void NETGeographicLib::TransverseMercator::Reverse ( double  lon0,
double  x,
double  y,
[System::Runtime::InteropServices::Out] double%   lat,
[System::Runtime::InteropServices::Out] double%   lon 
)

TransverseMercator::Reverse without returning the convergence and scale.


Property Documentation

double NETGeographicLib::TransverseMercator::MajorRadius [get]
Returns:
a the equatorial radius of the ellipsoid (meters). This is the value used in the constructor.

Definition at line 173 of file TransverseMercator.h.

double NETGeographicLib::TransverseMercator::Flattening [get]
Returns:
f the flattening of the ellipsoid. This is the value used in the constructor.

Definition at line 179 of file TransverseMercator.h.

double NETGeographicLib::TransverseMercator::CentralScale [get]
Returns:
k0 central scale for the projection. This is the value of k0 used in the constructor and is the scale on the central meridian.

Definition at line 185 of file TransverseMercator.h.


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