Universal Transverse Mercator coordinate system
The UTM system (of English Universal Transverse Mercator ) is a global coordinate system. It divides the earth's surface (from 80 ° South to 84 ° North ) strip-like in 6 ° wide vertical zones that are individually verebnet with the most favorable Transverse Mercator projection and coated with a Cartesian coordinate system.
For the mapping of the polar caps is the Universal Polar Stereographic projection ( UPS ) was used.
Both in Germany and in Austria UTM coordinates are used to the reference system ETRS89 reference to the GRS80 ellipsoid increased. In the national survey of other states will increasingly take the application of these. So that loses UTM related Gauss -Krüger coordinate system in the long term importance. Militärgeografische institutions are now using exclusively the Military Grid Reference System, in the German language also UTM reference system, short form UTMREF, which is a square plan - oriented geographic reporting system and is based on the UTM coordinate system.
History
The UTM coordinate system was developed in 1947 by the armed forces of the United States. In the context of internationalization, it should eventually replace the individual national coordinate systems. Thus, the Gauss -Krüger coordinate system is increasingly being replaced by the UTM system based on the reference ellipsoid WGS84 in the official German topographic maps now.
In Germany, the Working Committee of the Surveying Authorities of the States of the Federal Republic of Germany has approved the introduction of the ETRS89, which corresponds to the WGS84 datum as a single official position reference system for the whole of Germany in 1991 ( AdV ). For the period 1 January 1989 gaped namely the coordinates from WGS84 and ETRS89 apart by less than a meter, so both systems can be viewed within that location accuracy than the same. Furthermore, the AdV 1995 has decided to introduce comprehensively the UTM system in conjunction with the ETRS89 date. This is now for all survey administrations of Germany, the obligation to lead the real estate cadastre in the UTM / ETRS89. The Federal Agency for Cartography and Geodesy ( BKG) shall, through the GeoDataCentre the necessary geo-information in high accuracy. Today is the UTM / ETRS89 system in Germany by SAPOS, the Satellitenpositierungsdienst the German State Survey, highly accurate, homogeneous and implemented nationwide for all areas of surveying.
Also in Austria, the current federal reporting procedures, as used by the authorities and by the aid agencies, gradually replaced by the UTM coordinate system. More and more new maps on paper (eg car - Atlas ) have already hold this coordinate system shown in the diagram, as well as today's GPS navigation devices, the UTM system to WGS84 - based application as a standard.
Construction
UTM uses a transverse Mercator projection. Unlike the conventional Mercator projection of the projection surface does not touch the cylinder, but it cuts so that a strip-shaped part of the globe projecting from the cylinder surface. Characterized the shortened meridian in the middle between the Durchdringungskreisen in the projection by a factor of 0.9996. It is being said reproduced without distortion.
Since the transversal of the UTM projection underlying Mercator projection, heavily distorted areas that are far removed from the cut strips ( see pictures below ), UTM does not use a single projection to cover the entire Earth, but divides the earth in 6 ° wide so-called zones. Respectively, the mean meridian of the zone is then used as the reference meridian for projection. For example, zone 31 extends from 0 ° to 6 ° East. The reference meridian is at 3 ° East.
The Durchdringungskreise are in UTM projection 360 km apart, which corresponds to an angular distance of about 3 ° at the equator. At low latitudes, the zone is therefore wider than the cut strips. The areas outside the Durchdringungskreise be stretched in the projection, compressed within easy.
It is important to distinguish between the constant 360 km wide strip cut and the constant 6 ° wide zones. A zone defining a ( curved ) portion, in which a particular projection is to be used. This produces a planar projection image of the entire earth, which is coated with a Cartesian coordinate system or a grid. These coordinates are used but only within the associated zone. Together, zone and cut strips the reference meridian and the equator, or abscissa serve the ( then called the central meridian ) after projection into the plane as the axis of ordinates.
Zoning
The earth is divided between the 180th and the 180th degrees of west longitude east in 6 ° wide zones. In the center of the zones 60 thus formed extend the reference meridians 3 °, 9 °, 15 °, ... 177 °.
The zones are numbered from west to east. The zone of 180 ° to 174 ° west longitude given the code 1 from 174 ° to 168 ° numeral 2, etc. The German -speaking countries is mostly in the zones 32 (6 ° to 12 ° east longitude ), and 33 (12 ° to 18 ° ö.L. ) .
The zones from 80 ° latitude south to 84 degrees north latitude, divided by circles of latitude at a distance of 8 ° in zone fields that are labeled with letters. The southernmost zone field line has the letter C and the northernmost the letter X; only this northern boundary line X is slightly higher at 12 °. The letters I and O are omitted to avoid confusion with the numbers 1 and 0.
Only in Scandinavia there are fields with different widths ( ie east-west extension ): The zone field is 32V west widened by 3 ° to 9 °, so that Norway needs only this zone field. But here's the neighbor patch 31V narrower. On the northern edge of the strip zone belt ( in the fields line X, at 72 ° - 84 ° North ) cover 4 broadened zone fields ( 31X, 33X, 35X, 37X ) with 9 °, 12 °, 12 ° and 9 ° of latitude range from the prime meridian to 42 ° East from which is south of it regularly divided into 7 zone strips of 6 °. The right (east ) value of places in these a total of 6 width adjustment zone fields is changed from that meridian ( 500 km offset) determined that serves as the central meridian in the zones with the same number and 6 ° standard width.
The North Pole or South Pole regions are mapped with its own map projection, the Universal Polar Stereo Graphic projection. The south polar region, everything south than 80 ° S latitude, is divided into zones A ( 0 and 180 degrees west longitude ) and B ( 0 to 180 degrees east longitude ). The North Pole region, all further north than 84 ° north latitude, is in the zone Y ( west longitude ) and Z divided ( east longitude ). These codes are not used, but continued the letter code for the zone fields.
- The distribution of some continents in UTM zones
Africa
South America
Coordinates
To get to the coordinates of a point within a zone, as described above, the corresponding zone for UTM projection applied to the globe via the cylinder and unrolling his map into the plane. The ( projected ) equator now forms the X -axis, the central meridian, the Y -axis. X - and Y-axes are perpendicular to each other and to read the X and Y values as shown in a Cartesian coordinate system from, ie parallel to the axes, not to the now arcuate lines of longitude and latitude. The use of the X - axis for the right value and the Y- axis for the high value is common in geographic information systems, and also corresponds to the definition by the Working Committee of the Surveying Authorities of the States of the Federal Republic of Germany ( AdV ). In geodesy, the reverse interpretation of the coordinate axes used.
Only on the central meridian coincides the shape of the Y-axis ( grid north ) with true north. At remote from the central meridian coordinates it is not identical with true north. Therefore, many maps are characterized by the UTM system, the difference between grid north and true north, the so-called meridian convergence on the Y -axis with. This facilitates the use of orientation aids such as magnetic compasses, gyroscopes, stars.
By definition, the X value of the central meridian is rotated about 500,000 m ( "false easting "). This avoids the negative values west of the central meridian, which would arise if the X value of the central meridian would be 0 m. All acceptable legal values are therefore 100000-899999 meters, and are therefore always has six digits. As in the southern hemisphere and the Y values would be negative, people are going to the equator, by definition, the Y value of 10,000,000 meters and thereby also receives positive values. In the northern hemisphere, the equator gets the Y value of 0 m.
The X and Y value is given in meters. From the X ( right - ) value, the distance can be calculated for the central meridian and from the Y ( High ) value the proximity to the equator.
The resulting X value must be multiplied by the scale factor, the constant is 0.9996 ( other route distortion of the projection in this factor is not included). So you get the right value of the UTM coordinate. Of the high value is multiplied by the scale factor of the Y value. It is important to specify the appropriate zone number, otherwise the coordinate is ambiguous.
The Military Grid Reference System ( MGRS ) and UTM reference system ( UTMREF ) divides the zones in addition into squares measuring 100 km x 100 km parallel to the central meridian, regardless of the zone fields. The lattice fields receive pairs of letters as names and also serve to limit coordinates.
If you want to edit an area that spans multiple zones, the coordinate system of a zone can also be used on the zone boundaries, where the increasing distortions allow meaningful use yet.
Coordinates example
- Parade ground (Mannheim) Geographic coordinates ( WGS84) 49 ° 29 ' 13.6 " N
- 8 ° 27 ' 58.6 "E
- Zone 32 North ( grid square 32U is irrelevant to the calculation of the numerical values )
- Easting / Easting 461344
- North / Northing 5481745
- This results in a georeference 32 N 461344 5481745
- Common is the spelling 32U 461344 5481745 ( 'U' stands for the Latitude band of the corresponding UTM zone field )
- Zone 32U
- Grid square MV
- Easting / Easting 61344
- North / Northing 81745
- The complete georeference is so 32UMV 61344 81745
Areas of application
The UTM coordinate system or the UTM reference system finds application in the German Army, the civil defense, the fire service, ambulance service, the police and other agencies as well as in the survey. With appropriate training courses concerning card customer is always working according to the UTM coordinate system. In Germany it is a precise communication eg possible between the fire and a rescue helicopter. Other private applications (eg gliding, geocaching, etc.) are given with UTM maps on CD which are under the umbrella term Top50 for Germany, Austria and Switzerland (DA- CH) are commercially available. Also, Google Maps and Google Earth are most adjustable to the UTM coordinate system, and can, for example be used for application-oriented GPS navigation devices in the oil and gas search if better maps are missing.
Differences to the Gauss -Krüger system
The UTM coordinate system is similar to the Gauss -Krüger coordinate system. Both are a conformal mapping of the earth ellipsoid in the plane and can be calculated using the same imaging equations. The main difference is that Gauss-Krueger - coordinates relative in Germany on the Bessel ellipsoid or Krassowski and use 3 ° wide zones usually while UTM coordinates relative to the WGS84 or GRS80 ellipsoid the use and 6 ° wide zones.
With increasing strip width take at this compliant picture style the track distortions at the outer edge of the strip significantly. To compensate for the result of the wider meridian stronger image distortions ( enlargements ) to the zone edges is a scale factor of 0.9996 mounted at UTM. The central meridian is represented thus reduced by a factor of 0.9996 (40 cm / km). With increasing distance from the central meridian east or west, this shortening (y / R) 1/cos () decreases due to the increasing image distortion within the zone; at about 180 km Distance from the picture distortion reaches the factor 1 (length loyalty ). In the Gauss - Krüger coordinates are usually dispensed with such a correction, since the maximum distortion is still within its cadastral measurement accuracy.
Formal differences in the various approaches to the naming of the strip and the coordinates. Since UTM was originally introduced as a reporting system for the U.S. military, the appointment at UTM coordinates in the form of representation UTMREF / MGRS planquadrat oriented.