Usng_tools consists of libraries in various languages to make supporting the USNG (United States National Grid) and by association the MGRS easier. It supports converting to and from USNG/MGRS and Latitude/Longitude (additionally UTM and UPS conversions are supported in the appropriate zones.)
Support for the 4 UPS zones (A,B,Y & Z) near the poles requires the Proj4js library. Support for the 60 UTM zones is provided by a built in UTM library.
On conversion to USNG, the coordinates are produced based on the specified precision of the input.
On conversion to Lat/Lon from USNG, there is support for truncated coordinates (leaving out the grid zone or the grid zone and the 100km grid square designation). The ambiguity is resolved by finding the closest valid coordinate to a specified Lat/Lon. Also, there is support for locating coordinates in extended grid zones where the extension doesn't create any ambiguity.
Usng_tools started in April 2008 as a GeoMOOSE extension to support USNG coordinates. It was re-written and released as a separate library on GitHub in 2009 to help support the Sahana foundations' Haiti Earthquake relief effort.
In 2013, it was extended to work in the southern hemisphere and near the poles.
The USNG reference page can be found at: http://www.fgdc.gov/usng
Other references used:
- FGDC-STD-011-2001: http://www.fgdc.gov/standards/projects/FGDC-standards-projects/usng/fgdc_std_011_2001_usng.pdf
- MGRS specification: http://earth-info.nga.mil/GandG/publications/tm8358.1/tr83581b.html
- MGRS Zones A,B,Y,Z 100km grids: http://earth-info.nga.mil/GandG/coordsys/grids/universal_grid_system.html
<script src="proj4js-compressed.js"/>
<script src="usng2.js"/>u = new USNG2();
//
// Conversions from USNG to Lat/Lon
//
console.log(u.toLonLat( "18S UJ 228 070" ));
// Returns Object {lon: -77.04324684425941, lat: 38.8940174428622, precision: 3}
console.log(u.toLonLat( "UJ 228 070", {lon: -77, lat: 39} ));
// Returns Object {lon: -77.04324684425941, lat: 38.8940174428622, precision: 3}
console.log(u.toLonLat( "228 070", {lon: -77, lat: 39} ));
// Returns Object {lon: -77.04324684425941, lat: 38.8940174428622, precision: 3}
console.log(u.toLonLat( "B AN" ));
// Returns Object {lon: 0, lat: -90, precision: 0}
console.log(u.toLonLat( "Y ZP 12345 12345" ));
// Returns Object {lon: -171.85365493260602, lat: 84.43254784831868, precision: 5}
//
// Conversions from Lat/Lon to USNG
//
console.log(u.fromLonLat( { lon: -77.043, lat: 38.894 }, 3 ));
// Returns "18S UJ 228 069"
console.log(u.fromLonLat( { lon: -77.043, lat: 38.894 }, 5 ));
// Returns "18S UJ 22821 06997"Usng_tools is licensed under a MIT style license to encourage broad adoption.
Copyright (c) 2008-2013 James Klassen
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