Military Grid Reference System (MGRS)

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About

Military Grid Reference System, also called MGRS, is a system that a NATO country's military uses for locating a geographic location. It's based on UTM[1]. An MGRS measurement works roughly the same as a UTM measurement, but the military writes MGRS measurements in an abbreviated form. The MGRS uses a standard-scaled grid square, based on a point of origin on a map projection of the surface of the earth in an accurate and consistent manner to permit either position referencing or the computation of direction and distance between grid positions.[2]

How It Works

UTM and MGRS slices the world into long narrow strips. They zones typically have an assignment such as "10S" or "9N." These refer to a specific point on the earth.

From there, a UTM or MGRS measurement counts the physical number of meters north and east between that point and your location. This is called "northing" and "easting."[3] An example measure may look like this:

10 S 0559741 4282182

The "10 S" tells you which point ("zone") to measure from. The first number is always the "northing." It says our location is 559741 meters north of that point. Our "easting" of 4282182, tells us we are 4282182 meters east of that point.

The military abbreviates UTM measurements with MGRS. The length varies depending on how accurate you want the measurement to be. For example:

"10S5597414282182" contains all the data, down to 1 meter accuracy.

"10S5594282" abbreviates the data, down to 1 km accuracy.

Sources

  1. http://en.wikipedia.org/wiki/Military_grid_reference_system
  2. http://www.encyclopedia.com/doc/1O63-militarygridreferencsystm.html
  3. http://www.maptools.com/UsingUTM/quickUTM.html
Authors Rob Sanders
Editors Karl Yorgason
BoK Topics GD3
311 Weeks 8
Tags georeferencing system, UTM