GeographicLib
1.43

Convert between UTM/UPS and MGRS. More...
#include <GeographicLib/MGRS.hpp>
Static Public Member Functions  
static void  Forward (int zone, bool northp, real x, real y, int prec, std::string &mgrs) 
static void  Forward (int zone, bool northp, real x, real y, real lat, int prec, std::string &mgrs) 
static void  Reverse (const std::string &mgrs, int &zone, bool &northp, real &x, real &y, int &prec, bool centerp=true) 
static void  Check () 
Inspector functions  
static Math::real  MajorRadius () 
static Math::real  Flattening () 
Friends  
class  UTMUPS 
Convert between UTM/UPS and MGRS.
MGRS is defined in Chapter 3 of
This document has been updated by the two NGA documents
This implementation has the following properties:
The NGA software package geotrans also provides conversions to and from MGRS. Version 3.0 (and earlier) suffers from some drawbacks:
Example of use:

static 
Convert UTM or UPS coordinate to an MGRS coordinate.
[in]  zone  UTM zone (zero means UPS). 
[in]  northp  hemisphere (true means north, false means south). 
[in]  x  easting of point (meters). 
[in]  y  northing of point (meters). 
[in]  prec  precision relative to 100 km. 
[out]  mgrs  MGRS string. 
GeographicErr  if zone, x, or y is outside its allowed range. 
GeographicErr  if the memory for the MGRS string can't be allocated. 
prec specifies the precision of the MGRS string as follows:
UTM eastings are allowed to be in the range [100 km, 900 km], northings are allowed to be in in [0 km, 9500 km] for the northern hemisphere and in [1000 km, 10000 km] for the southern hemisphere. (However UTM northings can be continued across the equator. So the actual limits on the northings are [−9000 km, 9500 km] for the "northern" hemisphere and [1000 km, 19500 km] for the "southern" hemisphere.)
UPS eastings/northings are allowed to be in the range [1300 km, 2700 km] in the northern hemisphere and in [800 km, 3200 km] in the southern hemisphere.
The ranges are 100 km more restrictive than for the conversion between geographic coordinates and UTM and UPS given by UTMUPS. These restrictions are dictated by the allowed letters in MGRS coordinates. The choice of 9500 km for the maximum northing for northern hemisphere and of 1000 km as the minimum northing for southern hemisphere provide at least 0.5 degree extension into standard UPS zones. The upper ends of the ranges for the UPS coordinates is dictated by requiring symmetry about the meridians 0E and 90E.
All allowed UTM and UPS coordinates may now be converted to legal MGRS coordinates with the proviso that eastings and northings on the upper boundaries are silently reduced by about 4 nm (4 nanometers) to place them within the allowed range. (This includes reducing a southern hemisphere northing of 10000 km by 4 nm so that it is placed in latitude band M.) The UTM or UPS coordinates are truncated to requested precision to determine the MGRS coordinate. Thus in UTM zone 38n, the square area with easting in [444 km, 445 km) and northing in [3688 km, 3689 km) maps to MGRS coordinate 38SMB4488 (at prec = 2, 1 km), Khulani Sq., Baghdad.
The UTM/UPS selection and the UTM zone is preserved in the conversion to MGRS coordinate. Thus for zone > 0, the MGRS coordinate begins with the zone number followed by one of [C–M] for the southern hemisphere and [N–X] for the northern hemisphere. For zone = 0, the MGRS coordinates begins with one of [AB] for the southern hemisphere and [XY] for the northern hemisphere.
The conversion to the MGRS is exact for prec in [0, 5] except that a neighboring latitude band letter may be given if the point is within 5nm of a band boundary. For prec in [6, 11], the conversion is accurate to roundoff.
If prec = −1, then the "grid zone designation", e.g., 18T, is returned. This consists of the UTM zone number (absent for UPS) and the first letter of the MGRS string which labels the latitude band for UTM and the hemisphere for UPS.
If x or y is NaN or if zone is UTMUPS::INVALID, the returned MGRS string is "INVALID".
Return the result via a reference argument to avoid the overhead of allocating a potentially large number of small strings. If an error is thrown, then mgrs is unchanged.
Definition at line 123 of file MGRS.cpp.
References GeographicLib::UTMUPS::Reverse().
Referenced by GeographicLib::GeoCoords::AltMGRSRepresentation(), and GeographicLib::GeoCoords::MGRSRepresentation().

static 
Convert UTM or UPS coordinate to an MGRS coordinate when the latitude is known.
[in]  zone  UTM zone (zero means UPS). 
[in]  northp  hemisphere (true means north, false means south). 
[in]  x  easting of point (meters). 
[in]  y  northing of point (meters). 
[in]  lat  latitude (degrees). 
[in]  prec  precision relative to 100 km. 
[out]  mgrs  MGRS string. 
GeographicErr  if zone, x, or y is outside its allowed range. 
GeographicErr  if lat is inconsistent with the given UTM coordinates. 
std::bad_alloc  if the memory for mgrs can't be allocated. 
The latitude is ignored for zone = 0 (UPS); otherwise the latitude is used to determine the latitude band and this is checked for consistency using the same tests as Reverse.
Definition at line 39 of file MGRS.cpp.
References GeographicLib::UTMUPS::INVALID, GeographicLib::Math::isnan(), GeographicLib::UTMUPS::MAXZONE, GeographicLib::UTMUPS::MINZONE, and GeographicLib::Utility::str().

static 
Convert a MGRS coordinate to UTM or UPS coordinates.
[in]  mgrs  MGRS string. 
[out]  zone  UTM zone (zero means UPS). 
[out]  northp  hemisphere (true means north, false means south). 
[out]  x  easting of point (meters). 
[out]  y  northing of point (meters). 
[out]  prec  precision relative to 100 km. 
[in]  centerp  if true (default), return center of the MGRS square, else return SW (lower left) corner. 
GeographicErr  if mgrs is illegal. 
All conversions from MGRS to UTM/UPS are permitted provided the MGRS coordinate is a possible result of a conversion in the other direction. (The leading 0 may be dropped from an input MGRS coordinate for UTM zones 1–9.) In addition, MGRS coordinates with a neighboring latitude band letter are permitted provided that some portion of the 100 km block is within the given latitude band. Thus
The UTM/UPS selection and the UTM zone is preserved in the conversion from MGRS coordinate. The conversion is exact for prec in [0, 5]. With centerp = true, the conversion from MGRS to geographic and back is stable. This is not assured if centerp = false.
If a "grid zone designation" (for example, 18T or A) is given, then some suitable (but essentially arbitrary) point within that grid zone is returned. The main utility of the conversion is to allow zone and northp to be determined. In this case, the centerp parameter is ignored and prec is set to −1.
If the first 3 characters of mgrs are "INV", then x and y are set to NaN, zone is set to UTMUPS::INVALID, and prec is set to −2.
If an exception is thrown, then the arguments are unchanged.
Definition at line 158 of file MGRS.cpp.
References GeographicLib::UTMUPS::INVALID, GeographicLib::Utility::lookup(), GeographicLib::UTMUPS::MAXUTMZONE, GeographicLib::UTMUPS::MINUTMZONE, GeographicLib::Math::NaN(), GeographicLib::Utility::str(), and GeographicLib::UTMUPS::UPS.
Referenced by GeographicLib::GeoCoords::Reset().

inlinestatic 
(The WGS84 value is returned because the UTM and UPS projections are based on this ellipsoid.)
Definition at line 335 of file MGRS.hpp.
References GeographicLib::UTMUPS::MajorRadius().

inlinestatic 
(The WGS84 value is returned because the UTM and UPS projections are based on this ellipsoid.)
Definition at line 343 of file MGRS.hpp.
References GeographicLib::UTMUPS::Flattening().

static 
Perform some checks on the UTMUPS coordinates on this ellipsoid. Throw an error if any of the assumptions made in the MGRS class is not true. This check needs to be carried out if the ellipsoid parameters (or the UTM/UPS scales) are ever changed.
Definition at line 409 of file MGRS.cpp.
References GeographicLib::UTMUPS::Forward(), GeographicLib::UTMUPS::Reverse(), and GeographicLib::Utility::str().
Referenced by main().