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ED50 ("European Datum 1950", EPSG:4230 [1] ) is a geodetic datum which was defined after World War II for the international connection of geodetic networks.
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ED50 ("European Datum 1950", EPSG:4230 [1] ) is a geodetic datum which was defined after World War II for the international connection of geodetic networks.
Some of the important battles of World War II were fought on the borders of Germany, the Netherlands, Belgium and France, and the mapping of these countries had incompatible latitude and longitude positioning. During the war the German Military Survey (Reichsamt Kriegskarten und Vermessungswesen), under the command of Lieutenant General Gerlach Hemmerich, began a systematic mapping of the areas under the control of the German Military, a large part of Europe. [2] The allies were also concerned about the state of mapping in Europe, and in 1944 the US Army Map Service set up an intelligence team to collect mapping and surveying information from the Germans as the allied armies moved through Europe after the Normandy landings. The group, known as Houghteam after Major Floyd W. Hough, collected much material. Their greatest success was in April 1945. They found a large cache of material in Saalfeld, Thuringia, which proved to be the entire geodetic archives of the German Army. The shipment, 75 truckloads in all, was transferred to Bamberg, and then to Washington for evaluation. [3]
Shortly after this, the team captured the personnel of the Reichsamt für Landesaufnahme, the State Surveying Service, in Friedrichroda, also in Thuringia. This group had been working on the integration of the mapping of the occupied territories with that of Germany, under Professor Erwin Gigas, a geodesist with an international reputation. They were directed to continue this work, in Bamberg in the US zone of occupation, as part of the US-led effort to develop a single adjusted triangulation for Central Europe. This was completed in 1947. [4] [5] [6] The work was then extended to cover much of Western Europe which was completed in 1950, and became ED50. [4]
The European triangulation was originally classified military information. It was declassified in the 1960s, and became the basis for the definition of international boundaries in the North Sea. [7] It was, and still is, used in much of Western Europe apart from Great Britain, Ireland, Sweden and Switzerland, which have their own datums.
It used the International Ellipsoid of 1924 ("Hayford-Ellipsoid" of 1909) (radius of the Earth's equator 6378.388 km, flattening 1/297, both exact). That spheroid was an early attempt to model the whole Earth and was widely used around the world until the 1980s when GRS 80 and WGS 84 were established.
Many national coordinate systems of Gauss–Krüger are defined by ED50 and oriented by means of geodetic astronomy. Up to now it has been used in databases of gravity fields, cadastre, small surveying networks in Europe and America, and by some developing countries with no modern baselines. ED50 was also part of the fundamentals of the NATO coordinates (Gauss–Krüger and UTM) up to the 1980s.[ citation needed ]
The geodetic datum of ED50 was centred at the Helmertturm on the Telegrafenberg in Potsdam, (then East) Germany; the intent was to encourage cooperation with the socialist states during the cold war, which failed. The adjustments for later versions of the datum (ED77, ED79) used the Munich Frauenkirche as starting point.[ citation needed ]
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The longitude and latitude lines on the two datums are the same in the Archangel region of north-west Russia. As one moves westwards across Europe, the longitude lines on ED50 gradually become further west than their WGS 84 equivalents, and are around 100 metres west in Spain and Portugal. Moving southwards, the latitude lines on ED50 gradually become further south than the WGS 84 lines, and are around 100 m south in the Mediterranean Sea.
This means that if the lines are further west, the longitude value of any given point becomes more easterly. Similarly, if the lines are south, the values become northerly. This is due to the fact that the International Ellipsoid is larger than the GRS 80/WGS 84 ellipsoid, so a given north-south distance will cover more latitude on the new ellipsoid, and a given east-west distance will cover more longitude.
The datum shift for the Universal Transverse Mercator grid is different. The eastings vary between 0 m in Eastern Europe and 100 m in the far west of the continent, roughly similar to the longitude shift, but the northings are about 200 m different across Europe, with the ED50 UTM northing lines south of the WGS 84 UTM northing lines. UTM northings are measured from the Equator; distance from the equator to latitude 50 degrees is 112 m more on the International than on the WGS 84 spheroid.
Geodesy is the science of measuring and representing the geometry, gravity, and spatial orientation of the Earth in temporally varying 3D. It is called planetary geodesy when studying other astronomical bodies, such as planets or circumplanetary systems.
In geography, latitude is a coordinate that specifies the north–south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from −90° at the south pole to 90° at the north pole, with 0° at the Equator. Lines of constant latitude, or parallels, run east–west as circles parallel to the equator. Latitude and longitude are used together as a coordinate pair to specify a location on the surface of the Earth.
A geographic coordinate system (GCS) is a spherical or geodetic coordinate system for measuring and communicating positions directly on the Earth as latitude and longitude. It is the simplest, oldest and most widely used of the various spatial reference systems that are in use, and forms the basis for most others. Although latitude and longitude form a coordinate tuple like a cartesian coordinate system, the geographic coordinate system is not cartesian because the measurements are angles and are not on a planar surface.
A projected coordinate system – also called a projected coordinate reference system, planar coordinate system, or grid reference system – is a type of spatial reference system that represents locations on Earth using Cartesian coordinates (x, y) on a planar surface created by a particular map projection. Each projected coordinate system, such as "Universal Transverse Mercator WGS 84 Zone 26N," is defined by a choice of map projection (with specific parameters), a choice of geodetic datum to bind the coordinate system to real locations on the earth, an origin point, and a choice of unit of measure. Hundreds of projected coordinate systems have been specified for various purposes in various regions.
The World Geodetic System (WGS) is a standard used in cartography, geodesy, and satellite navigation including GPS. The current version, WGS 84, defines an Earth-centered, Earth-fixed coordinate system and a geodetic datum, and also describes the associated Earth Gravitational Model (EGM) and World Magnetic Model (WMM). The standard is published and maintained by the United States National Geospatial-Intelligence Agency.
The Ordnance Survey National Grid reference system (OSGB), also known as British National Grid (BNG), is a system of geographic grid references used in Great Britain, distinct from latitude and longitude.
The transverse Mercator map projection is an adaptation of the standard Mercator projection. The transverse version is widely used in national and international mapping systems around the world, including the Universal Transverse Mercator. When paired with a suitable geodetic datum, the transverse Mercator delivers high accuracy in zones less than a few degrees in east-west extent.
A geodetic datum or geodetic system is a global datum reference or reference frame for precisely representing the position of locations on Earth or other planetary bodies by means of geodetic coordinates. Datums are crucial to any technology or technique based on spatial location, including geodesy, navigation, surveying, geographic information systems, remote sensing, and cartography. A horizontal datum is used to measure a location across the Earth's surface, in latitude and longitude or another coordinate system; a vertical datum is used to measure the elevation or depth relative to a standard origin, such as mean sea level (MSL). Since the rise of the global positioning system (GPS), the ellipsoid and datum WGS 84 it uses has supplanted most others in many applications. The WGS 84 is intended for global use, unlike most earlier datums.
The European Terrestrial Reference System 1989 (ETRS89) is an ECEF geodetic Cartesian reference frame, in which the Eurasian Plate as a whole is static. The coordinates and maps in Europe based on ETRS89 are not subject to change due to the continental drift.
The Universal Transverse Mercator (UTM) is a map projection system for assigning coordinates to locations on the surface of the Earth. Like the traditional method of latitude and longitude, it is a horizontal position representation, which means it ignores altitude and treats the earth surface as a perfect ellipsoid. However, it differs from global latitude/longitude in that it divides earth into 60 zones and projects each to the plane as a basis for its coordinates. Specifying a location means specifying the zone and the x, y coordinate in that plane. The projection from spheroid to a UTM zone is some parameterization of the transverse Mercator projection. The parameters vary by nation or region or mapping system.
A spatial reference system (SRS) or coordinate reference system (CRS) is a framework used to precisely measure locations on the surface of Earth as coordinates. It is thus the application of the abstract mathematics of coordinate systems and analytic geometry to geographic space. A particular SRS specification comprises a choice of Earth ellipsoid, horizontal datum, map projection, origin point, and unit of measure. Thousands of coordinate systems have been specified for use around the world or in specific regions and for various purposes, necessitating transformations between different SRS.
The North American Datum (NAD) is the horizontal datum now used to define the geodetic network in North America. A datum is a formal description of the shape of the Earth along with an "anchor" point for the coordinate system. In surveying, cartography, and land-use planning, two North American Datums are in use for making lateral or "horizontal" measurements: the North American Datum of 1927 (NAD 27) and the North American Datum of 1983 (NAD 83). Both are geodetic reference systems based on slightly different assumptions and measurements.
The Earth-centered, Earth-fixed coordinate system, also known as the geocentric coordinate system, is a cartesian spatial reference system that represents locations in the vicinity of the Earth as X, Y, and Z measurements from its center of mass. Its most common use is in tracking the orbits of satellites and in satellite navigation systems for measuring locations on the surface of the Earth, but it is also used in applications such as tracking crustal motion.
The Bessel ellipsoid is an important reference ellipsoid of geodesy. It is currently used by several countries for their national geodetic surveys, but will be replaced in the next decades by modern ellipsoids of satellite geodesy.
An Earth ellipsoid or Earth spheroid is a mathematical figure approximating the Earth's form, used as a reference frame for computations in geodesy, astronomy, and the geosciences. Various different ellipsoids have been used as approximations.
The Hellenic Geodetic Reference System 1987 or HGRS87 is a geodetic system commonly used in Greece (SRID=2100). The system specifies a local geodetic datum and a projection system. In some documents it is called Greek Geodetic Reference System 1987 or GGRS87.
Transverse Mercator projection has many implementations. Louis Krüger in 1912 developed one of his two implementations that expressed as a power series in the longitude difference from the central meridian. These series were recalculated by Lee in 1946, by Redfearn in 1948, and by Thomas in 1952. They are often referred to as the Redfearn series, or the Thomas series. This implementation is of great importance since it is widely used in the U.S. State Plane Coordinate System, in national and also international mapping systems, including the Universal Transverse Mercator coordinate system (UTM). They are also incorporated into the Geotrans coordinate converter made available by the United States National Geospatial-Intelligence Agency. When paired with a suitable geodetic datum, the series deliver high accuracy in zones less than a few degrees in east-west extent.
Web Mercator, Google Web Mercator, Spherical Mercator, WGS 84 Web Mercator or WGS 84/Pseudo-Mercator is a variant of the Mercator map projection and is the de facto standard for Web mapping applications. It rose to prominence when Google Maps adopted it in 2005. It is used by virtually all major online map providers, including Google Maps, CARTO, Mapbox, Bing Maps, OpenStreetMap, Mapquest, Esri, and many others. Its official EPSG identifier is EPSG:3857, although others have been used historically.
Well-known text representation of coordinate reference systems is a text markup language for representing spatial reference systems and transformations between spatial reference systems. The formats were originally defined by the Open Geospatial Consortium (OGC) and described in their Simple Feature Access and Well-known text representation of coordinate reference systems specifications. The current standard definition is ISO 19162:2019. This supersedes ISO 19162:2015.
EPSG Geodetic Parameter Dataset is a public registry of geodetic datums, spatial reference systems, Earth ellipsoids, coordinate transformations and related units of measurement, originated by a member of the European Petroleum Survey Group (EPSG) in 1985. Each entity is assigned an EPSG code between 1024 and 32767, along with a standard machine-readable well-known text (WKT) representation. The dataset is maintained by the IOGP Geomatics Committee.