265 lines
13 KiB
C++
265 lines
13 KiB
C++
#pragma once
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/**
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* \file NETGeographicLib/AlbersEqualArea.h
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* \brief Header for NETGeographicLib::AlbersEqualArea class
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*
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* NETGeographicLib is copyright (c) Scott Heiman (2013)
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* GeographicLib is Copyright (c) Charles Karney (2010-2012)
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* <charles@karney.com> and licensed under the MIT/X11 License.
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* For more information, see
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* https://geographiclib.sourceforge.io/
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**********************************************************************/
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namespace NETGeographicLib
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{
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/**
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* \brief .NET Wrapper for GeographicLib::AlbersEqualArea.
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*
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* This class allows .NET applications to access
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* GeographicLib::AlbersEqualArea
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*
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* Implementation taken from the report,
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* - J. P. Snyder,
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* <a href="http://pubs.er.usgs.gov/usgspubs/pp/pp1395"> Map Projections: A
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* Working Manual</a>, USGS Professional Paper 1395 (1987),
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* pp. 101--102.
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*
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* This is a implementation of the equations in Snyder except that divided
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* differences will be [have been] used to transform the expressions into
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* ones which may be evaluated accurately. [In this implementation, the
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* projection correctly becomes the cylindrical equal area or the azimuthal
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* equal area projection when the standard latitude is the equator or a
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* pole.]
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*
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* The ellipsoid parameters, the standard parallels, and the scale on the
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* standard parallels are set in the constructor. Internally, the case with
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* two standard parallels is converted into a single standard parallel, the
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* latitude of minimum azimuthal scale, with an azimuthal scale specified on
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* this parallel. This latitude is also used as the latitude of origin which
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* is returned by AlbersEqualArea::OriginLatitude. The azimuthal scale on
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* the latitude of origin is given by AlbersEqualArea::CentralScale. The
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* case with two standard parallels at opposite poles is singular and is
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* disallowed. The central meridian (which is a trivial shift of the
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* longitude) is specified as the \e lon0 argument of the
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* AlbersEqualArea::Forward and AlbersEqualArea::Reverse functions.
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* AlbersEqualArea::Forward and AlbersEqualArea::Reverse also return the
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* meridian convergence, γ, and azimuthal scale, \e k. A small square
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* aligned with the cardinal directions is projected to a rectangle with
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* dimensions \e k (in the E-W direction) and 1/\e k (in the N-S direction).
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* The E-W sides of the rectangle are oriented γ degrees
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* counter-clockwise from the \e x axis. There is no provision in this class
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* for specifying a false easting or false northing or a different latitude
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* of origin.
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*
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* C# Example:
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* \include example-AlbersEqualArea.cs
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* Managed C++ Example:
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* \include example-AlbersEqualArea.cpp
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* Visual Basic Example:
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* \include example-AlbersEqualArea.vb
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*
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* <B>INTERFACE DIFFERENCES:</B><BR>
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* A constructor has been provided that creates the standard projections.
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*
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* The MajorRadius, Flattening, OriginLatitude, and CentralScale functions
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* are implemented as properties.
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**********************************************************************/
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public ref class AlbersEqualArea
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{
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private:
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// pointer to the unmanaged GeographicLib::AlbersEqualArea
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GeographicLib::AlbersEqualArea* m_pAlbersEqualArea;
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// Frees the unmanaged m_pAlbersEqualArea when object is destroyed.
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!AlbersEqualArea();
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public:
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/**
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Standard AlbersEqualAreaProjections that assume the WGS84 ellipsoid.
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*********************************************************************/
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enum class StandardTypes
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{
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CylindricalEqualArea, //!< cylindrical equal area projection (stdlat = 0, and \e k0 = 1)
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AzimuthalEqualAreaNorth, //!< Lambert azimuthal equal area projection (stdlat = 90°, and \e k0 = 1)
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AzimuthalEqualAreaSouth //!< Lambert azimuthal equal area projection (stdlat = −90°, and \e k0 = 1)
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};
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//! \brief Destructor
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~AlbersEqualArea() { this->!AlbersEqualArea(); }
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/**!
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* Constructor for one of the standard types.
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* @param[in] type The desired standard type.
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**********************************************************************/
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AlbersEqualArea( StandardTypes type );
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/**
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* Constructor with a single standard parallel.
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*
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* @param[in] a equatorial radius of ellipsoid (meters).
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* @param[in] f flattening of ellipsoid. Setting \e f = 0 gives a sphere.
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* Negative \e f gives a prolate ellipsoid.
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* @param[in] stdlat standard parallel (degrees), the circle of tangency.
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* @param[in] k0 azimuthal scale on the standard parallel.
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* @exception GeographicErr if \e a, (1 − \e f ) \e a, or \e k0 is
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* not positive.
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* @exception GeographicErr if \e stdlat is not in [−90°,
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* 90°].
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**********************************************************************/
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AlbersEqualArea(double a, double f, double stdlat, double k0);
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/**
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* Constructor with two standard parallels.
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*
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* @param[in] a equatorial radius of ellipsoid (meters).
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* @param[in] f flattening of ellipsoid. Setting \e f = 0 gives a sphere.
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* Negative \e f gives a prolate ellipsoid.
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* @param[in] stdlat1 first standard parallel (degrees).
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* @param[in] stdlat2 second standard parallel (degrees).
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* @param[in] k1 azimuthal scale on the standard parallels.
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* @exception GeographicErr if \e a, (1 − \e f ) \e a, or \e k1 is
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* not positive.
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* @exception GeographicErr if \e stdlat1 or \e stdlat2 is not in
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* [−90°, 90°], or if \e stdlat1 and \e stdlat2 are
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* opposite poles.
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**********************************************************************/
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AlbersEqualArea(double a, double f, double stdlat1, double stdlat2, double k1);
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/**
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* Constructor with two standard parallels specified by sines and cosines.
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*
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* @param[in] a equatorial radius of ellipsoid (meters).
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* @param[in] f flattening of ellipsoid. Setting \e f = 0 gives a sphere.
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* Negative \e f gives a prolate ellipsoid.
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* @param[in] sinlat1 sine of first standard parallel.
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* @param[in] coslat1 cosine of first standard parallel.
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* @param[in] sinlat2 sine of second standard parallel.
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* @param[in] coslat2 cosine of second standard parallel.
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* @param[in] k1 azimuthal scale on the standard parallels.
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* @exception GeographicErr if \e a, (1 − \e f ) \e a, or \e k1 is
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* not positive.
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* @exception GeographicErr if \e stdlat1 or \e stdlat2 is not in
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* [−90°, 90°], or if \e stdlat1 and \e stdlat2 are
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* opposite poles.
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*
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* This allows parallels close to the poles to be specified accurately.
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* This routine computes the latitude of origin and the azimuthal scale at
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* this latitude. If \e dlat = abs(\e lat2 − \e lat1) ≤ 160°,
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* then the error in the latitude of origin is less than 4.5 ×
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* 10<sup>−14</sup>d;.
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**********************************************************************/
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AlbersEqualArea(double a, double f,
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double sinlat1, double coslat1,
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double sinlat2, double coslat2,
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double k1);
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/**
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* Set the azimuthal scale for the projection.
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*
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* @param[in] lat (degrees).
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* @param[in] k azimuthal scale at latitude \e lat (default 1).
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* @exception GeographicErr \e k is not positive.
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* @exception GeographicErr if \e lat is not in (−90°,
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* 90°).
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*
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* This allows a "latitude of conformality" to be specified.
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**********************************************************************/
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void SetScale(double lat, double k);
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/**
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* Forward projection, from geographic to Lambert conformal conic.
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*
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* @param[in] lon0 central meridian longitude (degrees).
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* @param[in] lat latitude of point (degrees).
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* @param[in] lon longitude of point (degrees).
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* @param[out] x easting of point (meters).
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* @param[out] y northing of point (meters).
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* @param[out] gamma meridian convergence at point (degrees).
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* @param[out] k azimuthal scale of projection at point; the radial
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* scale is the 1/\e k.
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*
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* The latitude origin is given by AlbersEqualArea::LatitudeOrigin().
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* No false easting or northing is added and \e lat should be in the
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* range [−90°, 90°]. The values of \e x and \e y
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* returned for points which project to infinity (i.e., one or both of
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* the poles) will be large but finite.
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**********************************************************************/
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void Forward(double lon0, double lat, double lon,
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[System::Runtime::InteropServices::Out] double% x,
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[System::Runtime::InteropServices::Out] double% y,
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[System::Runtime::InteropServices::Out] double% gamma,
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[System::Runtime::InteropServices::Out] double% k);
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/**
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* Reverse projection, from Lambert conformal conic to geographic.
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*
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* @param[in] lon0 central meridian longitude (degrees).
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* @param[in] x easting of point (meters).
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* @param[in] y northing of point (meters).
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* @param[out] lat latitude of point (degrees).
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* @param[out] lon longitude of point (degrees).
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* @param[out] gamma meridian convergence at point (degrees).
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* @param[out] k azimuthal scale of projection at point; the radial
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* scale is the 1/\e k.
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*
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* The latitude origin is given by AlbersEqualArea::LatitudeOrigin().
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* No false easting or northing is added. The value of \e lon returned
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* is in the range [−180°, 180°). The value of \e lat
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* returned is in the range [−90°, 90°]. If the input
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* point is outside the legal projected space the nearest pole is
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* returned.
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**********************************************************************/
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void Reverse(double lon0, double x, double y,
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[System::Runtime::InteropServices::Out] double% lat,
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[System::Runtime::InteropServices::Out] double% lon,
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[System::Runtime::InteropServices::Out] double% gamma,
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[System::Runtime::InteropServices::Out] double% k);
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/**
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* AlbersEqualArea::Forward without returning the convergence and
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* scale.
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**********************************************************************/
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void Forward(double lon0, double lat, double lon,
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[System::Runtime::InteropServices::Out] double% x,
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[System::Runtime::InteropServices::Out] double% y);
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/**
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* AlbersEqualArea::Reverse without returning the convergence and
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* scale.
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**********************************************************************/
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void Reverse(double lon0, double x, double y,
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[System::Runtime::InteropServices::Out] double% lat,
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[System::Runtime::InteropServices::Out] double% lon);
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/** \name Inspector functions
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**********************************************************************/
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///@{
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/**
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* @return \e a the equatorial radius of the ellipsoid (meters). This is
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* the value used in the constructor.
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**********************************************************************/
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property double MajorRadius { double get(); }
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/**
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* @return \e f the flattening of the ellipsoid. This is the value used in
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* the constructor.
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**********************************************************************/
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property double Flattening { double get(); }
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/**
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* @return latitude of the origin for the projection (degrees).
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*
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* This is the latitude of minimum azimuthal scale and equals the \e stdlat
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* in the 1-parallel constructor and lies between \e stdlat1 and \e stdlat2
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* in the 2-parallel constructors.
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**********************************************************************/
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property double OriginLatitude { double get(); }
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/**
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* @return central scale for the projection. This is the azimuthal scale
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* on the latitude of origin.
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**********************************************************************/
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property double CentralScale { double get(); }
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///@}
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};
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} // namespace NETGeographic
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