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Hellenic Geodetic Reference System 1987
The Hellenic Geodetic Reference System 1987 or HGRS87 ( el, Ελληνικό Γεωδετικό Σύστημα Αναφοράς 1987 or ΕΓΣΑ'87) 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''. HGRS87 datum HGRS87 specifies a non-geocentric datum that is tied to the coordinates of the key geodetic station at the Dionysos Satellite Observatory (DSO) northeast of Athens (). The central pedestal (CP) at this location has by definition HGRS87 coordinates 38° 4' 33.8000" N - 23° 55' 51.0000"E, N = +7 m. Although HGRS87 uses the GRS80 ellipsoid, the origin is shifted relative to the GRS80 geocenter, so that the ellipsoidal surface is best for Greece. The specified offsets relative to WGS84 (WGS84-HGRS87) are: Δx = -199.87 m, Δy = 74.79 m, Δz = 246.62 m. The HGRS87 datum is implemented by a first order ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geodetic System
A geodetic datum or geodetic system (also: geodetic reference datum, geodetic reference system, or geodetic reference frame) 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''. DatumsThe plural is not "data" in this case 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. Befo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cartographic Projections
In cartography, map projection is the term used to describe a broad set of transformations employed to represent the two-dimensional curved surface of a globe on a plane. In a map projection, coordinates, often expressed as latitude and longitude, of locations from the surface of the globe are transformed to coordinates on a plane. Projection is a necessary step in creating a two-dimensional map and is one of the essential elements of cartography. All projections of a sphere on a plane necessarily distort the surface in some way and to some extent. Depending on the purpose of the map, some distortions are acceptable and others are not; therefore, different map projections exist in order to preserve some properties of the sphere-like body at the expense of other properties. The study of map projections is primarily about the characterization of their distortions. There is no limit to the number of possible map projections. More generally, projections are considered in several f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cadastre
A cadastre or cadaster is a comprehensive recording of the real estate or real property's metes-and-bounds of a country.Jo Henssen, ''Basic Principles of the Main Cadastral Systems in the World,'/ref> Often it is represented graphically in a cadastral map. In most countries, legal systems have developed around the original administrative systems and use the cadastre to define the dimensions and location of land parcels described in legal documentation. A land parcel or cadastral parcel is defined as "a continuous area, or more appropriately volume, that is identified by a unique set of homogeneous property rights". Cadastral surveys document the Boundary (real estate), boundaries of land ownership, by the production of documents, diagrams, sketches, plans (''plats'' in the US), charts, and maps. They were originally used to ensure reliable facts for land valuation and taxation. An example from early England is the Domesday Book in 1086. Napoleon established a comprehensive c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
European Terrestrial Reference System 1989
The European Terrestrial Reference System 1989 (ETRS89) is an ECEF (Earth-Centered, Earth-Fixed) 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 development of ETRS89 is related to the global ITRS geodetic datum, in which the representation of the continental drift is balanced in such a way that the total apparent angular momentum of continental plates is about 0. ETRS89 was officially born at the 1990 Florence meeting of EUREF, following its Resolution 1, which recommends that the terrestrial reference system to be adopted by EUREF will be coincident with ITRS at the epoch 1989.0 and fixed to the stable part of the Eurasian Plate. According to the resolution, this system was named European Terrestrial Reference System 89 (ETRS89). Since then ETRS89 and ITRS diverge due to the continental drift at a speed about 2.5 cm per y ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hellenic Terrestrial Reference System 2007
Hellenic is a synonym for Greek. It means either: *of or pertaining to the Hellenic Republic (modern Greece) or Greek people (Hellenes, el, Έλληνες) and culture *of or pertaining to ancient Greece, ancient Greek people, culture and civilization. It may also refer to: * Hellenic Academy, an independent high school in Harare, Zimbabwe * Hellenic Airlines * Hellenic College, a liberal arts college in Brookline, Massachusetts * Hellenic College of London * Hellenic Conservatory * Hellenic FC, a football club in South Africa * Hellenic Football League, an association football league in England * Hellenic languages, a branch of the Indo-European languages * Hellenic Parliament * Hellenic Petroleum (company) * Hellenic Post * Hellenic Republic Asset Development Fund * Hellenic studies * Tampa Bay Hellenic, a women's soccer team in the United States * Hellenic (horse) (1987–2011), a thoroughbred racehorse * ' See also * Greek (other) * Helladic period, the Bronze ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Military Grid Reference System
The Military Grid Reference System (MGRS) Datums, Ellipsoids, Grids, and Grid Reference Systems is the geocoordinate standard used by militaries for locating points on Earth. The MGRS is derived from the Universal Transverse Mercator (UTM) grid system and the Universal Polar Stereographic (UPS) grid system, but uses a different labeling convention. The MGRS is used as [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Universal Transverse Mercator Coordinate System
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 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. Most zones in UTM span 6 degrees of longitude, and each has a designated central meridian. The scale factor at the central meridian is specified to be 0.9996 of true scale for most UTM systems in use. History The National Oceanic and Atmospheric Administration (NOAA) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ED50
ED50 ("European Datum 1950", EPSG:4230) is a geodetic datum which was defined after World War II for the international connection of geodetic networks. Background 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. 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PROJ
PROJ (formerly PROJ.4) is a library for performing conversions between cartographic projections. The library is based on the work of Gerald Evenden at the United States Geological Survey (USGS), but since 2019-11-26 is an Open Source Geospatial Foundation (OSGeo) project maintained by the PROJ Project Steering Committee (PSC). The library also ships with executables for performing these transformations from the command line. History The history of PROJ dates back to the late 1970s, and the first release of PROJ was developed by Gerald Evenden in the early 1980s as a Ratfor program. It was based on the General Cartographic Transformation Package or GCTP, which consisted of Fortran subroutines that could be used to project geographic data. The second release of PROJ from 1985 was rewritten in C to run on UNIX systems. The third release of PROJ from 1990, was expanded to support approximately 70 cartographic projections. Evenden further developed a fourth release in 1994, named ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Equator
The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can also be used for any other celestial body that is roughly spherical. In spatial (3D) geometry, as applied in astronomy, the equator of a rotating spheroid (such as a planet) is the parallel (circle of latitude) at which latitude is defined to be 0°. It is an imaginary line on the spheroid, equidistant from its poles, dividing it into northern and southern hemispheres. In other words, it is the intersection of the spheroid with the plane perpendicular to its axis of rotation and midway between its geographical poles. On and near the equator (on Earth), noontime sunlight appears almost directly overhead (no more than about 23° from the zenith) every day, year-round. Consequently, the equator has a rather stable daytime temperature throu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cartographic Projection
In cartography, map projection is the term used to describe a broad set of transformations employed to represent the two-dimensional curved surface of a globe on a plane. In a map projection, coordinates, often expressed as latitude and longitude, of locations from the surface of the globe are transformed to coordinates on a plane. Projection is a necessary step in creating a two-dimensional map and is one of the essential elements of cartography. All projections of a sphere on a plane necessarily distort the surface in some way and to some extent. Depending on the purpose of the map, some distortions are acceptable and others are not; therefore, different map projections exist in order to preserve some properties of the sphere-like body at the expense of other properties. The study of map projections is primarily about the characterization of their distortions. There is no limit to the number of possible map projections. More generally, projections are considered in several f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transverse Mercator
The transverse Mercator map projection (TM, TMP) 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. Standard and transverse aspects The transverse Mercator projection is the transverse aspect of the standard (or ''Normal'') Mercator projection. They share the same underlying mathematical construction and consequently the transverse Mercator inherits many traits from the normal Mercator: * Both projections are cylindrical: for the Normal Mercator, the axis of the cylinder coincides with the polar axis and the line of tangency with the equator. For the transverse Mercator, the axis of the cylinder lies in the equatorial plane, and the line of tangency is any chosen meridian, thereby designat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
