GeographicLib::GeoCoords Class Reference

Conversion between geographic coordinates. More...

#include <GeographicLib/GeoCoords.hpp>

List of all members.

Public Member Functions

Initializing the GeoCoords object



 GeoCoords ()
 GeoCoords (const std::string &s, bool centerp=true, bool swaplatlong=false)
 GeoCoords (real latitude, real longitude, int zone=UTMUPS::STANDARD)
 GeoCoords (int zone, bool northp, real easting, real northing)
void Reset (const std::string &s, bool centerp=true, bool swaplatlong=false)
void Reset (real latitude, real longitude, int zone=UTMUPS::STANDARD)
void Reset (int zone, bool northp, real easting, real northing)
Querying the GeoCoords object



Math::real Latitude () const
Math::real Longitude () const
Math::real Easting () const
Math::real Northing () const
Math::real Convergence () const
Math::real Scale () const
bool Northp () const
char Hemisphere () const
int Zone () const
Setting and querying the alternate zone



void SetAltZone (int zone=UTMUPS::STANDARD) const
int AltZone () const
Math::real AltEasting () const
Math::real AltNorthing () const
Math::real AltConvergence () const
Math::real AltScale () const
String representations of the GeoCoords object



std::string GeoRepresentation (int prec=0, bool swaplatlong=false) const
std::string DMSRepresentation (int prec=0, bool swaplatlong=false, char dmssep=char(0)) const
std::string MGRSRepresentation (int prec=0) const
std::string UTMUPSRepresentation (int prec=0, bool abbrev=true) const
std::string UTMUPSRepresentation (bool northp, int prec=0, bool abbrev=true) const
std::string AltMGRSRepresentation (int prec=0) const
std::string AltUTMUPSRepresentation (int prec=0, bool abbrev=true) const
std::string AltUTMUPSRepresentation (bool northp, int prec=0, bool abbrev=true) const
Inspector functions



Math::real MajorRadius () const
Math::real Flattening () const

Detailed Description

Conversion between geographic coordinates.

This class stores a geographic position which may be set via the constructors or Reset via

The state consists of the latitude and longitude and the supplied UTM or UPS coordinates (possibly derived from the MGRS coordinates). If latitude and longitude were given then the UTM/UPS coordinates follows the standard conventions.

The mutable state consists of the UTM or UPS coordinates for a alternate zone. A method SetAltZone is provided to set the alternate UPS/UTM zone.

Methods are provided to return the geographic coordinates, the input UTM or UPS coordinates (and associated meridian convergence and scale), or alternate UTM or UPS coordinates (and their associated meridian convergence and scale).

Once the input string has been parsed, you can print the result out in any of the formats, decimal degrees, degrees minutes seconds, MGRS, UTM/UPS.

Example of use:

// Example of using the GeographicLib::GeoCoords class

#include <iostream>
#include <exception>
#include <string>
#include <GeographicLib/GeoCoords.hpp>

using namespace std;
using namespace GeographicLib;

int main() {
  try {
    // Miscellaneous conversions
    double lat = 33.3, lon = 44.4;
    GeoCoords c(lat, lon);
    cout << c.MGRSRepresentation(-3) << "\n";
    c.Reset("18TWN0050");
    cout << c.DMSRepresentation() << "\n";
    cout << c.Latitude() << " " << c.Longitude() << "\n";
    c.Reset("1d38'W 55d30'N");
    cout << c.GeoRepresentation() << "\n";
  }
  catch (const exception& e) {
    cerr << "Caught exception: " << e.what() << "\n";
    return 1;
  }
  return 0;
}

GeoConvert is a command-line utility providing access to the functionality of GeoCoords.

Definition at line 49 of file GeoCoords.hpp.


Constructor & Destructor Documentation

GeographicLib::GeoCoords::GeoCoords (  )  [inline]

The default constructor is equivalent to latitude = 90, longitude = 0.

Definition at line 77 of file GeoCoords.hpp.

GeographicLib::GeoCoords::GeoCoords ( const std::string &  s,
bool  centerp = true,
bool  swaplatlong = false 
) [inline, explicit]

Construct from a string.

Parameters:
[in] s 1-element, 2-element, or 3-element string representation of the position.
[in] centerp governs the interpretation of MGRS coordinates (see below).
[in] swaplatlong governs the interpretation of geographic coordinates (see below).
Exceptions:
GeographicErr if the s is malformed (see below).

Parse as a string and interpret it as a geographic position. The input string is broken into space (or comma) separated pieces and Basic decision on which format is based on number of components

  1. MGRS
  2. "Lat Long" or "Long Lat"
  3. "Zone Easting Northing" or "Easting Northing Zone"

The following inputs are approximately the same (Ar Ramadi Bridge, Iraq)

  • Latitude and Longitude
    • 33.44 43.27
    • N33d26.4' E43d16.2'
    • 43d16'12"E 33d26'24"N
    • 43:16:12E 33:26:24
  • MGRS
    • 38SLC30
    • 38SLC391014
    • 38SLC3918701405
    • 37SHT9708
  • UTM
    • 38n 339188 3701405
    • 897039 3708229 37n

Latitude and Longitude parsing: Latitude precedes longitude, unless a N, S, E, W hemisphere designator is used on one or both coordinates. If swaplatlong = true (default is false), then longitude precedes latitude in the absence of a hemisphere designator. Thus (with swaplatlong = false)

  • 40 -75
  • N40 W75
  • -75 N40
  • 75W 40N
  • E-75 -40S

are all the same position. The coordinates may be given in decimal degrees, degrees and decimal minutes, degrees, minutes, seconds, etc. Use d, ', and " to mark off the degrees, minutes and seconds. Various alternative symbols for degrees, minutes, and seconds are allowed. Alternatively, use : to separate these components. (See DMS::Decode for details.) Thus

  • 40d30'30"
  • 40d30'30
  • 4030'30
  • 40d30.5'
  • 40d30.5
  • 40:30:30
  • 40:30.5
  • 40.508333333

all specify the same angle. The leading sign applies to all components so -1d30 is -(1+30/60) = -1.5. Latitudes must be in the range [90, 90] and longitudes in the range [540, 540). Internally longitudes are reduced to the range [180, 180).

UTM/UPS parsing: For UTM zones (80 Lat < 84), the zone designator is made up of a zone number (for 1 to 60) and a hemisphere letter (n or s), e.g., 38n (38north can also be used). The latitude band designer ([C--M] in the southern hemisphere and [N--X] in the northern) should NOT be used. (This is part of the MGRS coordinate.) The zone designator for the poles (where UPS is employed) is a hemisphere letter by itself, i.e., n or s (north or south can also be used).

MGRS parsing interprets the grid references as square area at the specified precision (1m, 10m, 100m, etc.). If centerp = true (the default), the center of this square is then taken to be the precise position; thus:

  • 38SMB = 38n 450000 3650000
  • 38SMB4484 = 38n 444500 3684500
  • 38SMB44148470 = 38n 444145 3684705

Otherwise, the "south-west" corner of the square is used, i.e.,

  • 38SMB = 38n 400000 3600000
  • 38SMB4484 = 38n 444000 3684000
  • 38SMB44148470 = 38n 444140 3684700

Definition at line 176 of file GeoCoords.hpp.

GeographicLib::GeoCoords::GeoCoords ( real  latitude,
real  longitude,
int  zone = UTMUPS::STANDARD 
) [inline]

Construct from geographic coordinates.

Parameters:
[in] latitude (degrees).
[in] longitude (degrees).
[in] zone if specified, force the UTM/UPS representation to use a specified zone using the rules given in UTMUPS::zonespec.
Exceptions:
GeographicErr if latitude is not in [90, 90].
GeographicErr if longitude is not in [540, 540).
GeographicErr if zone cannot be used for this location.

Definition at line 193 of file GeoCoords.hpp.

GeographicLib::GeoCoords::GeoCoords ( int  zone,
bool  northp,
real  easting,
real  northing 
) [inline]

Construct from UTM/UPS coordinates.

Parameters:
[in] zone UTM zone (zero means UPS).
[in] northp hemisphere (true means north, false means south).
[in] easting (meters).
[in] northing (meters).
Exceptions:
GeographicErr if zone, easting, or northing is outside its allowed range.

Definition at line 207 of file GeoCoords.hpp.


Member Function Documentation

void GeographicLib::GeoCoords::Reset ( const std::string &  s,
bool  centerp = true,
bool  swaplatlong = false 
)

Reset the location from a string. See GeoCoords(const std::string& s, bool centerp, bool swaplatlong).

Parameters:
[in] s 1-element, 2-element, or 3-element string representation of the position.
[in] centerp governs the interpretation of MGRS coordinates.
[in] swaplatlong governs the interpretation of geographic coordinates.
Exceptions:
GeographicErr if the s is malformed.

Definition at line 18 of file GeoCoords.cpp.

References GeographicLib::DMS::Decode(), GeographicLib::DMS::DecodeLatLon(), GeographicLib::UTMUPS::DecodeZone(), GeographicLib::UTMUPS::Forward(), GeographicLib::UTMUPS::Reverse(), and GeographicLib::MGRS::Reverse().

void GeographicLib::GeoCoords::Reset ( real  latitude,
real  longitude,
int  zone = UTMUPS::STANDARD 
) [inline]

Reset the location in terms of geographic coordinates. See GeoCoords(real latitude, real longitude, int zone).

Parameters:
[in] latitude (degrees).
[in] longitude (degrees).
[in] zone if specified, force the UTM/UPS representation to use a specified zone using the rules given in UTMUPS::zonespec.
Exceptions:
GeographicErr if latitude is not in [90, 90].
GeographicErr if longitude is not in [540, 540).
GeographicErr if zone cannot be used for this location.

Definition at line 239 of file GeoCoords.hpp.

References GeographicLib::UTMUPS::Forward().

void GeographicLib::GeoCoords::Reset ( int  zone,
bool  northp,
real  easting,
real  northing 
) [inline]

Reset the location in terms of UPS/UPS coordinates. See GeoCoords(int zone, bool northp, real easting, real northing).

Parameters:
[in] zone UTM zone (zero means UPS).
[in] northp hemisphere (true means north, false means south).
[in] easting (meters).
[in] northing (meters).
Exceptions:
GeographicErr if zone, easting, or northing is outside its allowed range.

Definition at line 261 of file GeoCoords.hpp.

References GeographicLib::UTMUPS::Reverse().

Math::real GeographicLib::GeoCoords::Latitude (  )  const [inline]
Returns:
latitude (degrees)

Definition at line 279 of file GeoCoords.hpp.

Math::real GeographicLib::GeoCoords::Longitude (  )  const [inline]
Returns:
longitude (degrees)

Definition at line 284 of file GeoCoords.hpp.

Math::real GeographicLib::GeoCoords::Easting (  )  const [inline]
Returns:
easting (meters)

Definition at line 289 of file GeoCoords.hpp.

Math::real GeographicLib::GeoCoords::Northing (  )  const [inline]
Returns:
northing (meters)

Definition at line 294 of file GeoCoords.hpp.

Math::real GeographicLib::GeoCoords::Convergence (  )  const [inline]
Returns:
meridian convergence (degrees) for the UTM/UPS projection.

Definition at line 299 of file GeoCoords.hpp.

Math::real GeographicLib::GeoCoords::Scale (  )  const [inline]
Returns:
scale for the UTM/UPS projection.

Definition at line 304 of file GeoCoords.hpp.

bool GeographicLib::GeoCoords::Northp (  )  const [inline]
Returns:
hemisphere (false means south, true means north).

Definition at line 309 of file GeoCoords.hpp.

char GeographicLib::GeoCoords::Hemisphere (  )  const [inline]
Returns:
hemisphere letter n or s.

Definition at line 314 of file GeoCoords.hpp.

int GeographicLib::GeoCoords::Zone (  )  const [inline]
Returns:
the zone corresponding to the input (return 0 for UPS).

Definition at line 319 of file GeoCoords.hpp.

void GeographicLib::GeoCoords::SetAltZone ( int  zone = UTMUPS::STANDARD  )  const [inline]

Specify alternate zone number.

Parameters:
[in] zone zone number for the alternate representation.
Exceptions:
GeographicErr if zone cannot be used for this location.

See UTMUPS::zonespec for more information on the interpretation of zone. Note that zone == UTMUPS::STANDARD (the default) use the standard UPS or UTM zone, UTMUPS::MATCH does nothing retaining the existing alternate representation. Before this is called the alternate zone is the input zone.

Definition at line 338 of file GeoCoords.hpp.

References GeographicLib::UTMUPS::Forward(), GeographicLib::UTMUPS::MATCH, and GeographicLib::UTMUPS::StandardZone().

int GeographicLib::GeoCoords::AltZone (  )  const [inline]
Returns:
current alternate zone (return 0 for UPS).

Definition at line 356 of file GeoCoords.hpp.

Math::real GeographicLib::GeoCoords::AltEasting (  )  const [inline]
Returns:
easting (meters) for alternate zone.

Definition at line 361 of file GeoCoords.hpp.

Math::real GeographicLib::GeoCoords::AltNorthing (  )  const [inline]
Returns:
northing (meters) for alternate zone.

Definition at line 366 of file GeoCoords.hpp.

Math::real GeographicLib::GeoCoords::AltConvergence (  )  const [inline]
Returns:
meridian convergence (degrees) for alternate zone.

Definition at line 371 of file GeoCoords.hpp.

Math::real GeographicLib::GeoCoords::AltScale (  )  const [inline]
Returns:
scale for alternate zone.

Definition at line 376 of file GeoCoords.hpp.

string GeographicLib::GeoCoords::GeoRepresentation ( int  prec = 0,
bool  swaplatlong = false 
) const

String representation with latitude and longitude as signed decimal degrees.

Parameters:
[in] prec precision (relative to about 1m).
[in] swaplatlong if true give longitude first (default = false)
Exceptions:
std::bad_alloc if memory for the string can't be allocated.
Returns:
decimal latitude/longitude string representation.

Precision specifies accuracy of representation as follows:

  • prec = 5 (min), 1
  • prec = 0, 105 (about 1m)
  • prec = 3, 108
  • prec = 9 (max), 1014

Definition at line 60 of file GeoCoords.cpp.

References GeographicLib::Math::extra_digits(), and GeographicLib::Math::isnan().

string GeographicLib::GeoCoords::DMSRepresentation ( int  prec = 0,
bool  swaplatlong = false,
char  dmssep = char(0) 
) const

String representation with latitude and longitude as degrees, minutes, seconds, and hemisphere.

Parameters:
[in] prec precision (relative to about 1m)
[in] swaplatlong if true give longitude first (default = false)
[in] dmssep if non-null, use as the DMS separator character (instead of d, ', " delimiters).
Exceptions:
std::bad_alloc if memory for the string can't be allocated.
Returns:
DMS latitude/longitude string representation.

Precision specifies accuracy of representation as follows:

  • prec = 5 (min), 1
  • prec = 4, 0.1
  • prec = 3, 1'
  • prec = 2, 0.1'
  • prec = 1, 1"
  • prec = 0, 0.1" (about 3m)
  • prec = 1, 0.01"
  • prec = 10 (max), 1011"

Definition at line 78 of file GeoCoords.cpp.

References GeographicLib::DMS::Encode(), GeographicLib::Math::extra_digits(), GeographicLib::DMS::LATITUDE, and GeographicLib::DMS::LONGITUDE.

string GeographicLib::GeoCoords::MGRSRepresentation ( int  prec = 0  )  const

MGRS string.

Parameters:
[in] prec precision (relative to about 1m).
Exceptions:
std::bad_alloc if memory for the string can't be allocated.
Returns:
MGRS string.

This gives the coordinates of the enclosing grid square with size given by the precision. Thus 38n 444180 3684790 converted to a MGRS coordinate at precision 2 (100m) is 38SMB441847 and not 38SMB442848. prec specifies the precision of the MGRS string as follows:

  • prec = 5 (min), 100km
  • prec = 4, 10km
  • prec = 3, 1km
  • prec = 2, 100m
  • prec = 1, 10m
  • prec = 0, 1m
  • prec = 1, 0.1m
  • prec = 6 (max), 1m

Definition at line 87 of file GeoCoords.cpp.

References GeographicLib::MGRS::Forward().

string GeographicLib::GeoCoords::UTMUPSRepresentation ( int  prec = 0,
bool  abbrev = true 
) const

UTM/UPS string.

Parameters:
[in] prec precision (relative to about 1m)
[in] abbrev if true (the default) use abbreviated (n/s) notation for hemisphere; otherwise spell out the hemisphere (north/south)
Exceptions:
std::bad_alloc if memory for the string can't be allocated.
Returns:
UTM/UPS string representation: zone designator, easting, and northing.

Precision specifies accuracy of representation as follows:

  • prec = 5 (min), 100km
  • prec = 3, 1km
  • prec = 0, 1m
  • prec = 3, 1mm
  • prec = 6, 1m
  • prec = 9 (max), 1nm

Definition at line 126 of file GeoCoords.cpp.

string GeographicLib::GeoCoords::UTMUPSRepresentation ( bool  northp,
int  prec = 0,
bool  abbrev = true 
) const

UTM/UPS string with hemisphere override.

Parameters:
[in] northp hemisphere override
[in] prec precision (relative to about 1m)
[in] abbrev if true (the default) use abbreviated (n/s) notation for hemisphere; otherwise spell out the hemisphere (north/south)
Exceptions:
GeographicErr if the hemisphere override attempts to change UPS N to UPS S or vice versa.
std::bad_alloc if memory for the string can't be allocated.
Returns:
UTM/UPS string representation: zone designator, easting, and northing.

Definition at line 132 of file GeoCoords.cpp.

References GeographicLib::UTMUPS::Transfer().

string GeographicLib::GeoCoords::AltMGRSRepresentation ( int  prec = 0  )  const

MGRS string for the alternate zone. See GeoCoords::MGRSRepresentation.

Parameters:
[in] prec precision (relative to about 1m).
Exceptions:
std::bad_alloc if memory for the string can't be allocated.
Returns:
MGRS string.

Definition at line 95 of file GeoCoords.cpp.

References GeographicLib::MGRS::Forward().

string GeographicLib::GeoCoords::AltUTMUPSRepresentation ( int  prec = 0,
bool  abbrev = true 
) const

UTM/UPS string for the alternate zone. See GeoCoords::UTMUPSRepresentation.

Parameters:
[in] prec precision (relative to about 1m)
[in] abbrev if true (the default) use abbreviated (n/s) notation for hemisphere; otherwise spell out the hemisphere (north/south)
Exceptions:
std::bad_alloc if memory for the string can't be allocated.
Returns:
UTM/UPS string representation: zone designator, easting, and northing.

Definition at line 143 of file GeoCoords.cpp.

string GeographicLib::GeoCoords::AltUTMUPSRepresentation ( bool  northp,
int  prec = 0,
bool  abbrev = true 
) const

UTM/UPS string for the alternate zone, with hemisphere override.

Parameters:
[in] northp hemisphere override
[in] prec precision (relative to about 1m)
[in] abbrev if true (the default) use abbreviated (n/s) notation for hemisphere; otherwise spell out the hemisphere (north/south)
Exceptions:
GeographicErr if the hemisphere override attempts to change UPS n to UPS s or vice verse.
std::bad_alloc if memory for the string can't be allocated.
Returns:
UTM/UPS string representation: zone designator, easting, and northing.

Definition at line 150 of file GeoCoords.cpp.

References GeographicLib::UTMUPS::Transfer().

Math::real GeographicLib::GeoCoords::MajorRadius (  )  const [inline]
Returns:
a the equatorial radius of the WGS84 ellipsoid (meters).

(The WGS84 value is returned because the UTM and UPS projections are based on this ellipsoid.)

Definition at line 531 of file GeoCoords.hpp.

References GeographicLib::UTMUPS::MajorRadius().

Math::real GeographicLib::GeoCoords::Flattening (  )  const [inline]
Returns:
f the flattening of the WGS84 ellipsoid.

(The WGS84 value is returned because the UTM and UPS projections are based on this ellipsoid.)

Definition at line 539 of file GeoCoords.hpp.

References GeographicLib::UTMUPS::Flattening().


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