UTM reference system

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The UTM reference system ( UTMREF ) or message grid in the UTM mapping system . Military Grid Reference System ( MGRS ) is a rectangular grid square -oriented geographical signaling system and based on the UTM coordinate system and for the polar regions to the UPS coordinate system .

Division of the German UTM zones into grid squares

The meridian strips of the UTM reference coordinate system are divided into grid squares with a side length of 100 km. These grid squares are identified with a two-digit letter code, whereby - like the letters "I" and "O", remain unused in order to avoid confusion with 1 and 0. This pair of letters for the east and north values ​​of the grid square is added to the zone number / band code of the UTM reference system.

Within these grid squares, geographical information is now formulated as offsets to the southwest corner of the respective grid square, whereby the resolution - between 10 km and 1 m - is not specified explicitly, but is taken from the number of digits in the attached pair of numbers. By definition, both numbers are always the same length. Two single-digit numbers designate a 10 km grid square, two five-digit numbers designate a specific square meter of the earth's surface. In this way, extremely compact geographical information can be formulated.

A geographical indication in the UTM reference system is made up of

  • of the UTM zone, numbered from 1 to 60
  • the UTM tape, a letter between C and X.
  • the designation of the individual grid square, consisting of the pair of letters for the Easting and Northing values
  • a pair of numbers with the same number of digits between 1 and 5

Coordinate example

The coordinate specification 32UMD7403 is given . It can also be written as 32U MD 74 03 for better readability . This notation can be read as:

  • UTM zone 32 , a strip 6 degrees wide on both sides of the 9 ° longitude east (central meridian)
  • UTM band U , an 8 latitude high section of this zone between 48th and 56th parallel north. Since 8 degrees of latitude correspond to a distance of 887.6 km, the UTM bands are only approximately congruent with the nine grid squares in the north-south direction.
  • 100 km grid square MD , north on the central meridian 9 °
    • The letter M results in the 'horizontal' position (easting),
    • The letter D gives the 'vertical' position, the distance to the equator (northing).
  • Easting (Ostwert) 74 km within this grid square
  • Northing (high value) 03 km within this grid square

Each UTM zone is horizontally assigned 4 grid squares on both sides of the central meridian, which thus cover an 800 km wide strip. In UTM zone 32 these are the letters JKLM and NPQR. However, the first and eighth grid squares (J and R) already intersect at the equator with the outer grid squares of the neighboring zones. There the UTM zones have their maximum width of 668 km. This overlap increases to the north, and since the width of a UTM zone (6 degrees of longitude) decreases 6000 km north of the equator to less than 400 km, only 4 to 6 of these grid squares are generally used in our latitudes.

Coding of the grid squares

The two letter codes of a grid square are calculated taking into account the zone number as follows:

The first letter codes the easting value, i.e. the horizontal position of the grid square. Since each UTM zone is divided into eight grid squares in the west-east direction and the grid square letters are formed horizontally from a character set of 24 characters, the counting is repeated after every three UTM zones.

rest Easting (km)
100 200 300 400 500 600 700 800
1 A. B. C. D. E. F. G H
2 J K L. M. N P Q R.
0 S. T U V W. X Y Z

To determine the position of a grid square relative to the central meridian (easting), the zone number is divided by three as an integer. With the remainder of the division - one, two or zero - you go to the table above and there you can read out the easting value of the letter.

Calculation example:

  • Grid square 32 U M D
  • 32 modulo 3 = 2
  • The letter M marks the grid squares at E400, so the one you are looking for borders directly to the west on the central meridian.

Second letter, vertical coding of the Northing value

The letter code for describing the vertical position of the grid square is formed from a character set of 20 characters (A – V without I and O). It is repeated every 2000 km (20 grid squares at 100 km height).

In odd-numbered zones, counting starts at the equator with 'A', in even-numbered zones with 'F'.

In the figure, the resulting offset of the grid square designations between adjacent zones can be read off. In the zone 33 in the N6000 20 characters are counted by the third time, so that to the grid square UV north the grid square UA is connected. In even-numbered UTM zones, this change is offset by five grid squares to the south. Hence the change MV↔MA already with N5500.

application

The MGRS for Military Grid Reference System is used by the armed forces and the further NATO - forces used for the orientation and location information. Called the UTM reference system, it is also used in Germany for orientation by aid organizations and disaster control.

The Federal Network Agency writes in the currently valid "TR TKÜV " (Technical Directive on the implementation of legal measures for monitoring telecommunications and information requests for traffic data) provides that in the location specified in the monitoring of mobile devices, "UTM Ref coordinates" as "default the coordinate information ”can be used.

In Austria the coordinate system is used by the armed forces and the fire brigade , among others , while other organizations use either the UTM system or the older BMN system , but this is only used occasionally, as the corresponding maps have not been updated since 2010.

The UTM / MGRS coordinates are determined and transferred to topographic maps using a map pointer in the appropriate map scale.

Individual evidence

  1. ↑ Federal Network Agency: TR TKÜV Edition 6.0, December 2009, u. a. P. 48 (Annex B.2.15)

Web links

Commons : Military Grid Reference System  - collection of images, videos and audio files