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Topic: WGS84

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World Geodetic System

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	Geocaching Glossary
		Currently, Geocaching uses the WGS84 datum for all caches.
		Always check your GPS to ensure that WGS84 is the datum before entering a cache coordinate into your unit.
		The most current geodetic datum used for GPS is the World Geodetic System of 1984 (WGS84).
	www.geocaching.com /about/glossary.aspx (1048 words)

	Sect_2.1.4
		Its "x-axis" is the intersection of the WGS84 Reference Meridian Plane and the plane of the CTP Equator (the Reference Meridian being parallel to the Zero Meridian defined by BIH/IERS).
		The WGS84 system is the most widely used global reference system because it is the system in which the GPS satellite coordinates are expressed in the Navigation Message (section 3.3.3).
		The policy of Selective Availability was announced, whereby the WGS84 datum as realised by the contents of the GPS satellite coordinates and clock parameters within the broadcast Navigation Message could be corrupted.
	www.gmat.unsw.edu.au /snap/gps/gps_survey/chap2/214.htm (1885 words)

	Control point positioning using GPS
		As WGS84 coordinates for a particular site was not known neither it could be derived, in order to establish a reference station, Single Point Positioning technique of GPS has been applied for several hours of observation spanning in three consecutive days and night.
		WGS84 coordinates can be derived from local coordinates using appropriate transform function.
		Since, WGS84 coordinates for a particular site is not known neither it could be derived, Single Point Positioning technique of GPS has been applied for several hours of observation spanning in three consecutive days and night.
	www.gisdevelopment.net /technology/gps/techgp0030.htm (908 words)

	GPS Basics & Status of GPS in Qatar
		In order to relate the WGS84 coordinates derived from GPS to the Qatar National Datum (QND) coordinates used in Qatar a set of coordinate transformation parameters had to be computed.
		Because it is not possible to compute an errorless transformation between WGS84 and the existing QND datum, it was decided that a better approach would be to define a new QND datum that has an exact relationship to the WGS84 datum.
		WGS84 used in Qatar is defined by the United States Defense Mapping Agency (now NIMA) in their document "Department of Defense World Geodetic System 1984 - Its Definition and Relationship with Local Geodetic Systems", DMA TR 8350.2, dated September 30 1987 [Second Printing].
	www.gisqatar.org.qa /conf97/links/b1.html (4351 words)

	World Geodetic System - Wikipedia, the free encyclopedia
		The longitude positions on WGS84 agree with those on the older North American Datum 1927 at roughly 85 ° longitude west, in the east-central USA.
		By contrast, the zero meridian of WGS84 is about 100 metres east of the "traditional" Prime Meridian at Greenwich, UK.
		The latest major revision of WGS 84 is also referred to as "Earth Gravity Model 1996" (EGM 96), first published in 1996, with revisions as recent as 2004.
	en.wikipedia.org /wiki/WGS84 (2119 words)

	GPS - Reality bites
		WGS84 can therefore be termed as Geocentric world system which is accurate and close to the Nature (reality), where as Indian system is approximate, not geocentric (a local datum) and away from reality.
		To my mind derestriction of WGS84 may not be in our interest as it is an accurate system, which will be useful if launching pad and target of intercontinental missile are in WGS84, whereas if the coordinates are in local system.
		We should therefore consider derestricting maps/data in Indian system for civil use for development whereas data in WGS84 may have some restrictions, and may be used for defence and scientific purposes only.
	www.gisdevelopment.net /technology/gps/techgp0012.htm (879 words)

	Map Projections
		GPS or WGS84 data is unable to provide correct dimensional calculations due to the nature of the data in degrees longitude and latitude.
		The Raw Data WGS84 is provided on the next six sheets and labeled according to state and particular zone.
		The raw WGS84 data is contained on separate sheets and in degrees longitude and latitude.
	www.bae.uky.edu /~precag/modules/mod5ex1.htm (1712 words)

	MapTrax Australia: Topographic Map Formats Including FX4, BSB, Ozf2, ECW, TIFF, GEOTIFF, NOSGEO, WGS84, GDA94 (Site not responding. Last check: )
		The maps are calibrated in Latitude and Longitude at the four corners and a number of points across the map and the information is contained in the header file of each map.
		MapTrax Topographic Maps have been corrected to the equivalent of GDA94 datum by applying a correction to the map co-ordinates to achieve the shift which is close to 203 metres to the North East.
		However, any waypoints and routes created using the maps will be in WGS84 datum and can be backloaded to the GPS using that datum.
	www.maptrax.com.au /topographicmaps/topographicmapformats (831 words)

	[Geowanking] implicit wgs84 in geoweb coordinates until 2015 ?
		Following the long continuing discussions about the wisdom of automatically assuming wgs84 as the standard datum for describing coordinates, particularly elevation, in a prospective geoRSS or geoRDF, I made an effort today to shed some light on the dimensions of the issue.
		Gorilla_" http://www.iers.org/ " "The new global reference will certainly supplant wgs84 as the global standard datum by 2015" David also shared a few factoids: "55,000 USGS 7 1/2 minute topographic maps are encoded in nad27.
		And so, maybe it's OK until around 2015 to set a default datum, based on wgs84 for users to geocode their own information, but any generally useful mapping application, will have to include a fairly robust capability to import,convert, and render common external data.
	lists.burri.to /pipermail/geowanking/2005-October/002033.html (434 words)

	Welcome to GPS Network
		The WGS84 Cartesian axes and ellipsoid are geocentric; that is, their origin is the centre of mass of the whole Earth including oceans and atmosphere.
		This ensures that the Z axis of the WGS84 datum coincides with the International Reference Pole, and that the prime meridian of the ellipsoid (that is, the plane containing the Z and X Cartesian axes) coincides with the International Reference Meridian.
		Remember that the Cartesian axes and ellipsoid of WGS84 move steadily such that the motion is minimal with respect to the average of tectonic plate motions worldwide.
	www.ordnancesurvey.co.uk /oswebsite/gps/information/coordinatesystemsinfo/guidecontents/guide4.html (2518 words)

	Accuracy of AMSA's DGPS Reference Station Antenna Positions
		WGS84 was chosen because this coordinate system is used by the Global Positioning System (GPS), and the Australian Hydrographic Office produce charts, navigational publications and digital products in WGS84.
		This means that the transformed WGS84 position includes the uncertainty of the original AGD position and an additional uncertainty of up to several metres due to the transformation process.
		As WGS84 is aligned with ITRF at the level of a few centimetres, these positions can be used as WGS84 at this level of uncertainty.
	www.amsa.gov.au /Shipping_Safety/Navigation_Safety/Differential_Global_Postitioning_System/Accuracy (522 words)

	Kryptos
		Correspondingly, given a coordinate, it may map to several slightly different real-world locations depending on which datum you use to interpret it.
		WGS84 is the datum commonly used by GPSes (although many GPSes allow you to select from many datums).
		WGS84 is for most purposes _identical_ to NAD83.
	kryptos.arcticus.com /coords.html (833 words)

	Paragliding Forum - View topic - GPS - Which Geodetic ID ? - new
		WGS84 is the Standard Geodetic Datum (World Geodetic System 1984) and the common reference datum used for civilian aviation world wide.
		To answer your question: WGS84 is the standard for US paraglider comps, and has been since we began using GPS based flight verification at the 2001 Chelan Nationals.
		WGS84 is slowly becoming more standard though, hopefully less problems in future.
	www.paraglidingforum.com /viewtopic.php?t=1664 (973 words)

	OSSIM - Open Source Image Map: datum.h Source File (Site not responding. Last check: )
		WGS84 is used as an intermediate state when 00029 * shifting from one local datum to another.
		When geodetic coordinates are 00030 * given Molodensky's method is used, except near the poles where the 3-step 00031 * step method is used instead.
		Specific algorithms are used for shifting 00032 * between WGS72 and WGS84.
	www.remotesensing.org /doxygen/ossim/datum_8h-source.html (829 words)

	WGS84
		It is a system of terrestrial coordinates, based on a reference geoid taking the form of a revolution ellipsoide.
		WGS84 is a coordinate system including a model of the earth.
		These secondary parameters are made necessary because the WGS84 is not only used to define coordinates, but also to determine the GPS navigation satellites’; orbits.
	www.geoconcept.com /?580/WGS84 (99 words)

	Geo World - Aug 2005 - Mobile GIS: GPS Accuracy Improvements Highlight Datum Importance (Site not responding. Last check: )
		Some GIS professionals with educational backgrounds in geography were introduced to NAD83 and WGS84, but they were probably schooled on the notion that the difference between them is virtually negligible.
		ITRF00 and WGS84 (G1150) are similar, and the same divergence applies when compared against NAD83 (CORS96).
		Mobile GIS users who learned GPS mapping with submeter equipment didn't have to concern themselves with the shift between NAD83 and WGS84, because the discrepancy of a meter or less probably fell within the overall error budget.
	www.geoplace.com /Uploads/FeatureArticle/0508mgis.asp (793 words)

	Global and European Reference Systems: Theory and Practice
		The initial realization of WGS84 was purely based on positions computed based on observations from the Transit satellite system and was only accurate at the one to two metre level.
		A first step towards more consistency between the WGS84 and ITRS took place in 1993 when the complete WGS84 network was recomputed with respect to 8 GPS stations fixed to their ITRF91 position ([18]).
		The WGS84 ellipsoid (a=6378137 m, 1/f=298.257223563) is identical to the GRS80 ellipsoid at the mm level.
	www.gps.oma.be /gb/refsys_gb_ok_css.htm (4755 words)

	JAD2001 and GIS: A walk-through of the JAD 2001 - WGS84 datum transformation
		The advantage, of course, is that there is no need for a datum transformation to convert Jamaica Grid Coordinates to WGS84, and visa versa; one merely deals with the projection, the False Easting, and the False Northing.
		A 2D position will have the same latitude and longitude in both JAD 2001 and WGS84, thus ensuring that errors are not introduced by dodgy datum parameters when GPS derived positions are turned into Ja grid coordinates.
		To put it simply, WGS84 sea-level is not the actual level of the sea in Jamaica.
	www.jamaicancaves.org /jad2001.htm (646 words)

	USDA Forest Service Global Positioning System
		Once this correct wgs84 to nad83 method has been identified (typically NAD_1983_To_WGS_1984_1), this method should be selected in the projection dialogue of ArcToolbox to obtain the final NAD83 coordinate.
		In summary, the main point is this: Convert NAD27 coordinates collected in GPS to WGS84 using the same method that is used by the GPS (be it NADCON or another transformation method).
		This is generally correct, unless your GPS does not use NADCON to convert from WGS84 to NAD27 (which often is the case).
	www.fs.fed.us /database/gps/datum (969 words)

	Projections, Datums, And Transformations In ArcPad 7—Getting It Straight
		A transformation is required when incoming GPS coordinates are referenced to WGS84 and ArcPad’s map datum is referenced to NAD27 (or to NAD83) because these datums are based on different ellipsoids.
		Complications arise, however, as there are 21 different transformations that convert WGS84 coordinates to NAD27 coordinates, each one being suitable for a different portion of North America.
		For example, the table at right is suitable for transforming WGS84 coordinates to NAD27 coordinates in the western continental United States.
	www.fs.fed.us /database/gps/arcpad7/index.htm (1385 words)

	WGS84
		WGS84 est un système de coordonnées comprenant un modèle de la terre.
		Ces paramètres secondaires sont rendus nécessaires par le fait que WGS84 est employé non seulement pour définir des coordonnées, mais aussi pour déterminer les orbites des satellites de navigation GPS.
		Les "coordonnées GPS" renvoyées par un récepteur GPS sont en fait une latitude, une longitude et une altitude dans le système WGS84.
	www.geoconcept.com /?498/WGS84 (136 words)

	ANSCIA Barrow GCP Metadata
		Note that a few GCP codes (C004, C033, C057, C058) are not listed, as the GCP was aborted in the field, or the feature could not be confidently identified on aerial photographs.
		UTM Northing and Easting (z4, m): Zone 4 North, horizontal datum is WGS84, calculated from geographic coordinates using ArcInfo 8.1.
		Coordinates are referenced to the ITRF 94 reference frame, a specific subset of WGS84.
	instaar.colorado.edu /QGISL/barrow_gcp/metadata.html (664 words)

	Galdos Systems Inc » IS WGS84 Enough
		There are large amounts of data today which exist in hundreds of coordinate systems and conversion of all of this data is not going to happen.
		WGS84 is limited in accuracy (today) to a best 1 metre.
		IF I express the coordinates of a "straight line" segment (meaning linear interpolation) in WGS84 it will NOT be a shortest line on the surface of the earth.
	www.galdosinc.com /archives/190 (315 words)

	JAD69: The Jamaica Datum and the GPS (Site not responding. Last check: )
		In short, the latitudes and longitudes found on the Jamaican topos must be converted to WGS84, or the GPS datum must be user-defined to JAD69, to have the two agree.
		In the past, the JAD69 datum parameters seem to have been regarded as a "state secret" by certain departments of the Jamaican government, and were not freely available, but the recent publishing of a new set has established a precedent, (the cat is out of the bag).
		The actual referencing involves the use of a GPS mapping program and the determination of accurate calibration points at sites easily located on the map, usually road intersections, (the middle of the intersection is best; you'll find that on the digitized topos that the roads are shown as several times their actual width).
	www.jamaicancaves.org /jad69.htm (1816 words)

	W3C Semantic Web Interest Group: Basic Geo (WGS84 lat/long) Vocabulary
		This is a basic RDF vocabulary that provides the Semantic Web community with a namespace for representing lat(itude), long(itude) and other information about spatially-located things, using WGS84 as a reference datum.
		The vocabulary is getting significant usage, both (as intended) within RDF documents, but also as a namespace used within non-RDF XML documents, such as RSS 2.0 (see below).
		An RDF vocabulary for WGS84 latitude/longitude/altitude markup (namespace uri:
	www.w3.org /2003/01/geo (1501 words)

	Viestikallio Tools: KKJ/WGS84/Maidenhead
		Source format: KKJ P/I, KKJ Lat/Long, WGS84 Lat/Long, Maidenhead, Explanations.
		The method used for this tool is to iteratively search for a Lat/Long pair within a source rectangle so that it matches as closely to the user input as possible.
		Explanations for conversion from geographic KKJ coordinates (Finnish Hayford) to KKJ-P/I and WGS84 Lat/Long.
	www.viestikallio.fi /tools/kkj-wgs84.php?LANG=en (429 words)

	Geocode.com - EZ-Locate Introduces the WGS-84 Datum
		This geocentric (or earth-centered) datum uses the earth's center of mass as the origin of the datum.
		This is the same great Tele Atlas data, with the same great attributes that you have come to trust for your mission critical applications.
		For customers that are interested in transforming WGS84 data into NAD27, most GIS software packages support the transformation.
	www.geocode.com /modules.php?name=News&file=article&sid=4 (386 words)

	gmane.comp.gis.postgis
		"Reprojection" into WGS84 longlat (epsg:4326) works OK using Mapserver (fetching the data from postgres using the default epsg:27393 and projecting to epsg:4326 in Mapserver).
		I would say a warning should definitely be given if the transformation being done is not the one that was requested by the user.
		An important omission in my earlier emails (sorry...): The proj.4 epsg +lon_0 parameters (longitude offset) for the NGO projections have been strange for the last couple of proj.4 releases.
	comments.gmane.org /gmane.comp.gis.postgis/8090 (2562 words)

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