Date Austria
![](https://upload.wikimedia.org/wikipedia/commons/thumb/0/06/GuentherZ_2008-03-29_0741_Habsburgerwarte_Gedenktafel_Bundesamt_fuer_Eich-und_Vermessungswesen.jpg/220px-GuentherZ_2008-03-29_0741_Habsburgerwarte_Gedenktafel_Bundesamt_fuer_Eich-und_Vermessungswesen.jpg)
The Datum Austria reference system forms the geodetic basis of a map representation of the earth's surface optimized for Austria (see also geodetic date ). In Austria it is also referred to as the usage system , country coordinate system , MGI (this is the official abbreviation), MGI ( Ferro ) or AT_MGI . The OGP EPSG Code (i.e. the code of the European Petroleum Survey Group Geodesy ) for the date Austria is 4805.
The reference system is based on the triangulation of the Military Geographic Institute (MGI), which laid the foundations of the modern surveying network for the entire territory of Austria-Hungary around 1900 .
Requirements
The MGI reference system mainly includes the following specifications:
- as a reference ellipsoid for the mathematical figure of the earth the Bessel ellipsoid
- for its exact storage in the earth, the assumption of the astronomical latitude and longitude of the fundamental point Hermannskogel (highest mountain in Vienna )
- for orientation in the system of geographical coordinates, the adoption of the astronomical azimuth from the point Hermannskogel to the trigonometric point Hundsheimer Berg (near the border with Hungary and today's Slovakia ).
- The Gauß-Krüger coordinate system with the prime meridian of Ferro (17 ° 40 'west of Greenwich ) is currently used as the projection system .
use
The date Austria is based on e.g. As the Austrian Federal signaling network (BMN) and the ÖAMTC - road maps at a scale of 1: 150,000 ( Ed Hölzel. , Vienna). Further information on the history of the Austrian map reference systems can also be found in "Photogrammetric Engineering & Remote Sensing", March 2004.
history
With the independence of the individual nation states after the First World War , the MGI date was retained in Austria despite its peripheral location , in order not to have to change the coordinates of all survey points and millions of border points . The neighboring states to the east, however, went over to other fundamental points that were more central to their national territory .
Conversions
To coordinates that are z. For example, if you refer to the global WGS84 or European ETRS89 datum, to convert to coordinates in Datum Austria (and vice versa), a coordinate transformation is required.
Helmert transformation
The Helmert transformation is usually used for a distortion- free transformation between different reference systems . The following table lists the seven parameters of a Helmert transformation from the WGS84 or ETRS89 to the date Austria:
Starting system | Target system | c x (meters) | c y (meters) | c z (meters) | s ( ppm ) | r x ( arcsecond or new second ) | r y ( arcsecond or new second ) | r z ( arc second or new second ) |
---|---|---|---|---|---|---|---|---|
WGS84 | Date Austria | −577.326 | −90.129 | −463.919 | −2.4232 | 5.1366 "and 15.8537 cc, respectively |
1.4742 "or 4.5500 cc |
5.2970 "and 16.3489 cc, respectively |
With the Helmert transformation of WGS84 GPS data it should be noted that the parameters for distortion (s) and rotation (c x , c y , c z ) from the measurements of the Federal Office for Metrology and Surveying (BEV) are included in the of the AGREF ( Austrian Geodetic Reference Frame ) project are not or only to a limited extent suitable for uncorrected GPS receivers and software.
When using the Helmert transformation with the parameters of the BEV, an accuracy of an average of 1.5 m across Austria can be expected. A Helmert transformation cannot simply be reduced to a pure x, y, z shift.
Molodensky transformation
Alternatively, the three-parameter Molodenski transformation or a simple x, y, z shift can also be used.
In common GPS receivers , the following values are used for the Molodenski transformation of the WGS84 to the date Austria. The value ΔA relates to the difference in axial lengths from the WGS84 to the Bessel 1841 ellipsoid and the value ΔF to the difference in flattening :
Starting system | Target system | Brand / product | designation | c x (m) | c y (m) | c z (m) | ΔA (m) | ΔF (x10 4 ) |
---|---|---|---|---|---|---|---|---|
WGS84 | Date Austria | Garmin | Austria NS | 596 | 87 | 473 | 738 | 0.1003748 |
Magellan , others | User | 577.3 | 90.1 | 493.9 | 739.845 | 0.10037483 |
Program cs2cs
The program cs2cs, which is part of the PROJ.4 library, is suitable for converting coordinates that refer to the date Austria into other coordinate and reference systems and vice versa.
The EPSG codes for Austria are:
- Longitude and latitude: 3906, 4312, 4805
- transverse Mercator projection : 31251-31286 and 31288-31290
- Lambert projection : 31287.
As an example, the conversion of Gauß-Krüger coordinates based on the date Austria from a cadastral plan in eastern Austria ( Irenental ) into geographical longitude and latitude based on WGS84:
cs2cs +init=epsg:31256 +to +init=epsg:4326
In EPSG: 31256 the Helmert parameters are defined, which are given in the above table in the GPS line. You can also specify the parameters yourself. Depending on the number of parameters (3 or 7), the program decides which transformation (Molodenski or Helmert) is to be used. The command line is then:
cs2cs +proj=tmerc +ellps=bessel +lon_0=16.33333333333333 +x_0=0 +y_0=-5000000 \ +towgs84=577.326,90.129,463.919,5.137,1.474,5.297,2.4232 +units=m \ +to +proj=longlat +ellps=WGS84 +datum=WGS84
See also
- Land surveying , gaping , consistency
- Gaussian land survey , Prussian land survey , measuring table sheet
- Central European Network , German Main Triangle Network (DHDN), European Date 1950 (ED50)
Web links
- ASPRS Grids & Datums - Republic of Austria (PDF; 57 kB)
- PROJ.4 library of coordinate reference systems
- Library in the Go programming language for converting BMN coordinates into Lat / Long and vice versa