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Topic: GRS80

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World Geodetic System

	Ordnance Survey Ireland :: Geodetic services :: Overview :: GPS Reference Systems
		WGS84 is a geocentric reference ellipsoid and a geodetic datum, in that it defines the centre of mass of the earth as its origin, and the direction of the earth's axis as the minor axis of the reference ellipsoid.
		GRS80 is a further refinement of the WGS84, and is coincident with WGS84 at the metre level.
		During the late 1980's and early 1990's the increased use of GPS for mapping and scientific work highlighted the need for a reference network compatible with the new technology and essential to relate the mapping framework to global and continental reference systems.
	www.osi.ie /gps/overview/gps.asp (918 words)

	GRS80 (Site not responding. Last check: )
		GRS80, or Geodetic Reference System 1980, is a geodetic reference system consisting of a reference ellipsoid and a gravity field model.
		GRS80 chooses as these and, making the geometical constant a derived quantity.
		The GRS80 reference system is used by the Global Positioning System, in a realization called WGS 84 (World Geodetic System 1984).
	www.publicliterature.org /en/wikipedia/g/gr/grs80.html (158 words)

	[No title]
		The units for the listed ellipsoids are given in meters, and therefore the distances are also given in meters.
		Note that for the purpose of this application GRS80 and WGS84 are considered to be equivalent.
		The program works exclusively on the GRS80 ellipsoid and the units are meters.
	www.ngs.noaa.gov /TOOLS/Inv_Fwd/Inv_Fwd.html (580 words)

	Geoscience Australia: Geodesy - Datums and Coordinates
		They have a small difference in the definition of their ellipsoid parameters and generally may be treated as the same.
		The GRS80 is important to Australia as it is the ellipsoid used to define the GDA94.
		The flattening of the ellipsoid is referred to by the letter 'f' and is a measure of how much the ellipsoid differs from a sphere.
	www.ga.gov.au /geodesy/datums/aboutdatums.jsp (2554 words)

	Earth's Geoid (Site not responding. Last check: )
		X,Y (horizontal coordinates) are referenced to an ellipsoid.
		GRS80 is currently the most commonly used elliptical model used for the globe,though a new ellipsoid has recently been developed by the National Geodetic Survey and will likely replace GRS80 for future projects.
		The Clarke 1866 ellipsoid is a predecessor to the GRS80 ellipsoid.
	solid_earth.ou.edu /notes/geoid/earths_geoid.htm (1677 words)

	Amazon.com: GRS80: Books (Site not responding. Last check: )
		The ellipsoid of WGS84 is virtually identical to the GRS80 ellipsoid." In the coterminous states of the United States, this...
		-40 0 -1 0 240 -30 GRS80 -10 240 -40 the -30 relative to 210 -20 -4...
		NAD83 is based on the GRS80 spheroid, whose origin is located at the Earth's center of...
	www.amazon.com /s?ie=UTF8&keywords=GRS80&tag=httpexplaguid-20&index=books&link_code=qs&page=1 (947 words)

	Spartanburg SC \| GoUpstate.com \| Spartanburg Herald-Journal (Site not responding. Last check: )
		It is based on the GRS80 ellipsoid; an ellipsoid derived from satellite geodesy.
		A point having a given latitude and longitude in NAD27 may be displaced on the order of many tens of meters from another point having the identical latitude and longitude in NAD83.
		The North American Datum of 1927 is defined by the latitude and longitude of an initial point (Meades Ranch in Kansas), the direction of a line between this point and a specified second point, and two dimensions that define the spheroid.
	www.goupstate.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=North_American_Datum (309 words)

	Cartography Vocabulary Chapter 2
		The imaginary line of the earth's coordinate system that is formed by passing a plane through the center of the earth perpendicular to the axis of rotation and midway between the poles is the: (a) axis; (b) loxodrome; (c) Prime Meridian; (d) GRS80; (e) equator.
		The science that measures the size and shape of the earth which often involves measurement of the external gravitational field of the earth is: (a) photogrammetry; (b) geodesy; (c) cartology; (d) pedology; (e) hydrology.
		A projection that preserves correct linear relationships between a point and several other points or between two points which cannot show correct linear distance between all points to all other points is BEST termed: (a) antipodal; (b) geodetic; (c) conformal; (d) equivalent; (e) equidistant.
	www.jsu.edu /depart/geography/mhill/cart/cvch2.html (1441 words)

	[Proj] GRS80 vs GRS80 +towgs84=0,0,0
		Maciek, In the case you specify the +towgs84, no ellipsoid conversion is done.
		In the case without +towgs84, an ellipsoid conversion is done.
		The WGS84 and GRS80 are essentially the same but there is a small difference.
	lists.maptools.org /pipermail/proj/2005-December/001912.html (159 words)

	Point of Beginning Message Board - Messages View
		GRS80, WGS84, and NAD83 are all ellipsoids that provide a practical model the Earth's shape.
		I also read that it differs slightly from GRS80 becuase of better measurements and adjustments used in calculating the Earth's shape.
		The ellipsoid used by WGS84 differs from GRS80 because of a rounding error, but the difference is so tiny that it makes to discernable difference in any practical application.
	www.i-boards.com /bnp/pob/messages.asp?MsgID=974768&ThreadID=93661&IsResponse=True (708 words)

	Project 1: Sample Report (Site not responding. Last check: )
		The change from an ellipsoid generated based on a point on the surface of the earth (Clarke 1866), to one that's point of origin is the Earth's center of mass (GRS80), in essence "moved" the control points defined by the National Geodetic Survey, NGS.
		The GRS80 ellipsoid is comparable with the WGS84 ellipsoid that GPS technology uses as its reference for measurement.
		When the SPC was revised based on NAD83, using the GRS80 ellipsoid, three states, Nebraska (from 2 regions to 1), Montana (3 to 1) and South Carolina (2 to 1) all requested that only one projection be used for the entirety of the state.
	www.personal.psu.edu /jbm227/Project1A.htm (2009 words)

	The MathWorks - Demos - Plotting a 3-D Dome as a Mesh Over a Globe
		Use the Global Reference System of 1980 (GRS80) and work in units of kilometers.
		grs80 = almanac('earth','grs80','km'); domeRadius = 3000; % km domeLat = 39; % degrees domeLon = -77; % degrees domeAlt = 0;
		Notice how the hemisphere becomes tilted and how its center moves thousands of kilometers from the origin.
	www.mathworks.com /products/mapping/demos.html?file=/products/demos/shipping/map/mapex3ddome.html (524 words)

	Datums
		The Australian Map Grid 1984 (AMG84) eastings and northings are derived from AGD84 geographical co-ordinates using the UTM projection from ANS.
		The Geodetic Reference System 1980 (GRS80) is the global reference spheroid adopted by the IAG in 1980.
		The MGA is UTM projection of the GDA geographical co-ordinates using Redfern’s formulae with the geometrical constants of GRS80.
	members.iinet.net.au /~cadres/datum.htm (369 words)

	Welcome to OS Net
		Because the ellipsoid shape doesn't fit the Earth perfectly, there are lots of different ellipsoids in use, some of which are designed to best, fit the whole Earth and some to best fit just one region.
		The ellipsoid used for mapping in Britain, the Airy 1830 ellipsoid, is designed to best-fit Britain only, which it does better than GRS80, but; it is not useful in other parts of the world.
		The modern trend is to use GRS80 everywhere for reasons of global compatibility.
	www.ordnancesurvey.co.uk /gps/information/coordinatesystemsinfo/guidecontents/guide2.html (1500 words)

	News \| Gainesville.com \| The Gainesville Sun \| Gainesville, Fla. (Site not responding. Last check: )
		The relationship depends on the internal density distribution, or, in simplest terms, the degree of central concentration of mass.
		The 1980 Geodetic Reference System (GRS80) posited a 6,378,137 m semi-major axis and a 1:298.257 flattening.
		The numerous other systems which have been used by diverse countries for their maps and charts are gradually dropping out of use as more and more countries move to global, geocentric reference systems using the GRS80 reference ellipsoid.
	www.gainesville.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=GRS80 (414 words)

	Corners of SGPE bounding rectangles
		To overlay data at different resolutions, therefore, the LAS/ERDAS upper left corner easting or longitude should be increased by one-half the grid cell size, and the northing or latitude decreased by one-half the grid cell size.
		North American mapping agencies are in the process of moving from the 1927 datum (NAD27), which uses the Clarke 1866 spheroid, to the 1983 datum (NAD83), which uses the GRS80 spheroid (identical to within a few mm to the WGS84 spheroid) derived from satellite geodessy.
		Note that, because the radii and eccentricities of the spheroids are different, the differences between eastings and northings for a given map projection will include not only the offsets given above, but also the difference in arc lengths associated with the angular displacement between a given point and the coordinate origin for the projection.
	dbwww.essc.psu.edu /dbtop/amer_n/us_sc/sgpr/data/corners.html (844 words)

	[No title]
		Regarding the survey results in 1999, the results of the coordinates (latitude, longitude, ellipsoidal height) of GRS80 coordinate system have been first gained.
		Next, the results of the other five types of coordinate have been gained by calculation processing of coordinate conversion in the order of 2) -> 3) -> 4) -> 5) -> 6) on the basis of these coordinate results.
		The latitude, longitude and ellipsoidal height of GRS80 coordinate system have been converted to X,Y and Z of ITRF94 coordinate system according to the following formula:
	ksp.nict.go.jp /survey/1/1.3.htm (419 words)

	nxbase: nxGeodetic class Reference
		Others are available, like GRS80, MERIT83 and WGS84 but there is very little to choose between the different models.
		The important point is that all of the geoids are within ~100 m of the true (gravitational) shape of the Earth which is much better than the ~20 km errors if one uses a pure sphere.
		Much of the convergence criteria could be easily coded up and adjusted to follow the oblate spheroid semi-major axis but it has not yet been done.
	osirus.usask.ca /osiris/software/documentation/library/nxbase/html/classnxGeodetic.html (1636 words)

	[GRASS5] adding a new datum/projection? (Site not responding. Last check: )
		This is pretty much the same as WGS84 but uses the GRS80 ellipsoid (slightly different flattening parameter).
		The old 5.0.2 version asks for ellipsoid first, then datum, but complains when you try to mix wgs84 and grs80 and quits without writing anything.
		The latest g.setproj never gives you a chance to set the ellipsoid, it is chosen from your datum.
	grass.itc.it /pipermail/grass5/2003-July/008335.html (332 words)

	Proceedings of Research Works 1998
		Its ability to serve the conventional survey techniques will be ensured by a set of plane coordinates Y, X in the national "Křovák's" map projection accomplished by sea level heights referred to the "Baltic Vertical Datum after Adjustment".
		A strategy for the setup of a reference frame represented by coordinates of 176 stations determined by an appropriate combination of the results of all relevant campaigns is described in (Kostelecký, Šimek, 1995).
		Due to the fact the new system S-JTSK/95 keeps spatial relations between geocentric ellipsoid GRS80 and Bessel ellipsoid, it is necessary to use ellipsoidal instead of sea level heights for transformation.
	www.vugtk.cz /odis/sborniky/sb98/kostel.htm (2704 words)

	2970.0.55.009 - 2001 Census of Population and Housing - Fact Sheet: Geocentric Datum of Australia and Australian Bureau ...
		In the MapInfo export format files (.mif/.mid files) supplied by the ABS, the datum is specified as 116 (GDA94).
		When these tables are imported into MapInfo, the software converts this to Datum 33 (Geodetic Reference System, 1980 - GRS80).
		GDA94 is one of a number of datums which are equivalent to GRS80.
	www.abs.gov.au /ausstats/abs@.nsf/Latestproducts/2970.0.55.009Main%20Features12001?opendocument&tabname=Summary&prodno=2970.0.55.009&issue=2001&num=&view= (701 words)

	Datums--Who Needs 'Em Anyway?
		Instead of defining the earth from surface measurements linked horizontally and related vertically to mean sea level, this new mathematical approximation was derived from a point located out in space.
		This spheroid and its associated datums define the earth's shape by measuring and triangulating from an outside perspective and use the mass center of the earth as an absolute origin.
		Using the GRS80 spheroid, new datums were developed both regionally and worldwide.
	www.esri.com /news/arcuser/0401/datum.html (896 words)

	[GRASS5] adding a new datum/projection?
		This is > pretty much the same as WGS84 but uses the GRS80 ellipsoid (slightly > different flattening parameter).
		GRASS uses a very limited definition of a datum which really just comes down to the ellipsoid used, so by changing the ellipsoid you are really taking away everything the datum stands for.
		ellps: grs80 towgs84: 0,0,0 and make sure there is no 'datum' line.
	grass.itc.it /pipermail/grass5/2003-July/008337.html (789 words)

	[GRASS5] Some Bugs
		Part of the problem is that r.in.gdal takes a generic PROJ.4 representation of the projection, and tries to massage it a bit to be suitable for GRASS.
		PROJ.4 is case insensitive about ellipsoid names, and so my code happens to produce "grs80" instead of "GRS80".
		I think the most important thing is to ensure that GRASS remains case insensitive.
	grass.itc.it /pipermail/grass5/2000-December/010863.html (553 words)

	Amazon.com: GRS80 (Site not responding. Last check: )
		is virtually identical to the GRS80 ellipsoid." In the coterminous states...
		Parameters Ellipsoid a (m) 1/f GRS80 6,378,137.0 298.257222101 WGS84 6,378,137.0 298.257223563...
		NAD83 is based on the GRS80 spheroid, whose origin is located...
	www.amazon.com /s?ie=UTF8&platform=gurupa&keywords=GRS80&search-type=ss&tag=vepoware14-20&index=blended&link_code=qs&page=1 (1101 words)

	Foro Cartesia :: Ver tema - grs80 vs. wgs84
		Publicado: Mie 01 Jun 2005, 21:33 Asunto: grs80 vs. wgs84
		cual es la diferencia entre grs80 (geodetic reference system 1980) y el wgs84 (world geodetic system 1984).
		Encontré esta otra página donde se pueden apreciar algunas aclaraciones entre GRS80 y WGS84.
	www.cartesia.org /foro/viewtopic.php?t=408&sid=305421079407a8017c19328e059d847e (610 words)

	NOOBEED - As Geodesy and Surveying Software (Site not responding. Last check: )
		For example a point having latitude 40 deg 30 min 15.276 sec, longitude -99 deg 20 min 30.256 sec, h = 20 meters, can be transform to space rectangular coordinate as follows.
		Please note that "GRS80" is a name of pre-defined ellipsoid in Noobeed.
		By using a pre-defined ellipsoid name, coorect parameters, a and f of an ellipsoid, will be assigned automatically to the ellipsoid object.
	www.noobeed.com /nb_ex_geod.htm (1252 words)

	GRS80 - Gurupedia
		GRS80, or Geodetic Reference System 1980, is a geodetic reference system consisting of a reference ellipsoid and a gravity field model.
		Additional derived physical constants and geodetic formulas are found in the following reference: Geodetic Reference System 1980, Bulletin Géodésique, Vol 54:3, 1980.
		The GRS80 reference system is used by the Global Positioning System, in a realization called WGS 84 (World Geodetic System 1984).
	www.gurupedia.com /g/gr/grs80.htm (177 words)

	DoIR - Minerals and Petroleum - GDA and Petroleum Titles
		In Australia, the new datum will be labelled the Geocentric Datum of Australia (GDA) which uses the GRS80, (Geodetic Reference System), spheroid in order to come into line with the rest of the World.
		The benefits of the change to the new spheroid have been recognised and are supported by government and industry.
		Please Note: GRS80 and WGS84 parameters are almost identical and for the purposes
	www.doir.wa.gov.au /mineralsandpetroleum/caddc3994b374840b68539a9d90bb771.asp (294 words)

	Datums
		The Australian Map Grid 1984 (AMG84) eastings and northings are derived from AGD84 geographical co-ordinates using the UTM projection from ANS.
		The Geodetic Reference System 1980 (GRS80) is the global reference spheroid adopted by the IAG in 1980.
		The MGA is UTM projection of the GDA geographical co-ordinates using Redfern’s formulae with the geometrical constants of GRS80.
	members.iinet.com.au /~cadres/datum.htm (369 words)

	NOAA-USGS Bathy/Topo/Shoreline: Tampa Bay Demonstration Project- DEM development (Site not responding. Last check: )
		Fifteen spatial and temporal filters were applied to the 47 digital NOAA hydrographic surveys, dating from 1945 to 1996, which cover the Tampa Bay region.
		The vertical coordinates represent elevation in decimal meters relative to the GRS80 ellipsoid, and the horizontal coordinates are decimal degrees of latitude and longitude referenced to the NAD83 datum.
		Because the source bathymetric and topographic data vary in density and accuracy, users need to be made aware of the spatially varying quality of the merged model.
	chartmaker.ncd.noaa.gov /bathytopo/Deansweb/DEM_development.htm (1049 words)

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