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Topic: WGS 84

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World Geodetic System

Geodesy

GRS80

Reference ellipsoid

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Colonial History of the United States

	WGS 84 Wikipedia, Flickr, Delicious Bash at Bashr.com (Site not responding. Last check: 2007-11-07)
		Therefore, a motivation, and a substantial problem in the WGS and similar work is to patch together datums that were not only made separately, for different regions, but to re-reference the elevations to an ellipsoid model rather than to the geoid.
		In accomplishing WGS 60, a combination of available surface gravity data, astro-geodetic data and results from HIRAN and Canadian SHORAN surveys were used to define a best-fitting ellipsoid and an earth-centered orientation for each of the initially selected datums (Chapter IV).
		The defining parameters of the WGS 66 Ellipsoid were the flattening (1/298.25), determined from satellite data and the semimajor axis (6,378,145 meters), determined from a combination of Doppler satellite and astro-geodetic data.
	www.bashr.com /en_bio_pics/WGS_84 (2019 words)

	NGA: (U) WGS 84 Earth Gravitational Model (UNCLASSIFIED)
		The NGA/NASA 15-minute worldwide geoid height file and the WGS 84, n=m=360, EGM96 coefficient file are approved for official DoD use as documented in NGA TR8350.2, Third Edition, 4 July 1997.
		The 30-minute geoid height file and the WGS 84, n=m=180, EGM coefficient file described on the WGS 84 (180,180) web pages are approved for DoD use as documented in DMA TR8350.2, Second Edition, 1 September 1991.
		WGS 84 TECHNICAL REPORT - NIMA TR8350.2 - Third Edition, 4 July 1997 is available on-line and in hard-copy.
	earth-info.nga.mil /GandG/wgs84/gravitymod/index.html (266 words)

	World Geodetic System 1984 (WGS 84)
		Doppler stations positioned within WGS 84 with known local geodetic system coordinates were the basic ingredient in the development of Local Geodetic System-to-WGS 84 Datum Shifts.
		The most accurate approach for obtaining WGS 84 coordinates is to acquire satellite tracking data at the site of interest and position it directly in WGS 84 using the Satellite Point Positioning technique.
		In addition, the WGS 84 earth gravity model and geoid are considerably more accurate than their WGS 72 counterparts, and minor scale, translation, and orientation errors inherent in WGS 72 are reduced in WGS 84.
	www.ctsystems.org /wgs84doc.htm (750 words)

	GIS Data, Jobs, Software, News, and Fun - GeoCommunity
		WGS 72 is an earlier, less accurate global geocentric reference system; transformation from this datum to that of WGS 84 would only be required for navigation purposes at chart scales 1:50,000 and larger.
		Thus, the logical datum shift to WGS 84 can be quite large, depending on the area of the world and the local datum in use, as in the case of the Tokyo datum.
		The database, on WGS 84 datum, is compiled from a global portfolio of over 5,000 NIMA and National Oceanic and Administration Agency charts (U.S. waters) that supports marine navigation between 84° North latitude and 81° South latitude.
	www.geocomm.com /channel/gps/news/nimagps2 (1751 words)

	WGS 84
		WGS 84 is the 1984 revision of the World Geodetic System.
		It defines a fixed global reference frame for the Earth, for use in geodesy and navigation.
		Earlier schemes included WGS 72[?], WGS 64[?] and WGS 60[?].
	www.ebroadcast.com.au /lookup/encyclopedia/wg/WGS_84.html (37 words)

	[No title]
		Except for the largest map scales, the horizontal components of WGS 84 and NAD 83 may be considered equivalent.
		WGS 84, WGS 84 (G730), WGS 84 (G873), and NAD 83 (86) It is not well known that there is more than one WGS 84 reference frame.
		WGS 84 (orig.) -- Broadcast GPS orbit from January 23, 1987 to June 28, 1994.
	chartmaker.ncd.noaa.gov /bathytopo/DennisWeb/tutor.doc (3508 words)

	WGS 84 Mathematics
		This model goes through new revisions every few years (See WGS 60, 66, 72, and the 1994 upgrade of the WGS 84).
		Each version was intended to supercede its predecessors, although in many cases the older versions (especially WGS 72) were built into equipment too expensive or time-consuming to upgrade, keeping them in common use long after the newer versions were standard.
		While a sphere would be incorrect by approximately 14 km at the poles and 7 km at the equator, this oblate spheroid is only incorrect by at most 110 meters (as discussed in the EGM 96 section), with an average error of 20-30m.
	www.pha.jhu.edu /~hanish/WGS.html (440 words)

	Notes on GPS
		The ellipsoid radii for WGS 84 are as follows, noting that the FAI Sphere is 6371 km for the purpose of measurement for FAI purposes:
		WGS 84 is the latest standard for the whole world but may not an exact fit in a given area.
		A WGS 84 ellipsoid provides a reference surface upon which coordinates are calculated and is particularly applicable to inertial systems.
	www.buzzplus.com /gps.html (1965 words)

	NGS FAQs
		WGS 84 is used by DoD for all its mapping, charting, surveying, and navigation needs, including its GPS "broadcast" and "precise" orbits.
		WGS 84 was defined in January 1987 using Doppler satellite surveying techniques.
		WGS 84 (G873) was adopted as the reference frame for broadcast orbits on January 29, 1997.
	www.ngs.noaa.gov /faq.shtml (5354 words)

	dti: Oil and Gas Directorate - Regulation: Guidance notes (Site not responding. Last check: 2007-11-07)
		Due to tectonic motion, ETRF89 is not identical to global realisations of WGS 84.
		The discrepancy between ETRF89 and WGS 84 in Europe is about 20cm (in 1998) and growing at 2-3cm per year.
		WGS 84 includes an ellipsoid of the same name (WGS84) which for all practical purposes is the same as the GRS80 ellipsoid.
	www.og.dti.gov.uk /regulation/guidance/co_systems/co_sys_12.htm (1228 words)

	Map Datums
		WGS 84 was adopted as a world standard from a datum called the North American Datum of 1983 or NAD 83.
		In the Continental United States the difference between WGS 84 and NAD 27 can be as much as 200 meters.
		If you are coordinating with aircraft, they will likely have their datum set to WGS 84, as most aviation charts now use WGS 84.
	www.maptools.com /UsingUTM/mapdatum.html (465 words)

	Relation of NAD 83 To WGS 84 (Site not responding. Last check: 2007-11-07)
		Both NAD 83 and WGS 84 were defined (in words) to be geocentric, and oriented as the BIH Terrestrial System.
		The WGS 84 ellipsoid differs very slightly from the GRS 80 ellipsoid which was used for NAD 83.
		Similarly, if the coordinates of the old point in WGS 84 are used, the coordinates of the new point are said to be in WGS 84.
	www.mentorsoftwareinc.com /RESOURCE/Nad83.htm (2304 words)

	84 (number) - Wikipedia, the free encyclopedia
		The duration of Saros series 84 was 1280.1 years, and it contained 72 solar eclipses.
		The duration of Saros series 84 was 1496.5 years, and it contained 84 lunar eclipses.
		WGS 84 - The latest revision of the World Geodetic System, a fixed global reference frame for the Earth.
	en.wikipedia.org /wiki/84_(number) (265 words)

	WGS 84 Geographic Point URI Space
		This is a specification of a URI space representing points on Earth according to the World Geodetic System 1984 (WGS 84).
		WGS 84 is an earth fixed global reference frame, including an earth model.
		A geographic point on the Earth's surface representing a longitude of -126.81 degrees and a latitude of 46.183 degrees.
	placetime.com /geopoint/wgs84 (288 words)

	Compound Coordinate Transformations
		A geodetic datum transformation from Bogota, with a Bogota prime meridian, to WGS 84 is really two transformations.
		One is a shift of the prime meridian to Greenwich, followed by a datum shift to WGS 84.
		Thus, a transformation from ETRS89 to WGS 84 would be given as a pair of transformations: ETRS89 to WGS 72, followed by WGS 72 to WGS 84.
	www.posc.org /technical/up223/comcord.html (892 words)

	Professional Surveyor Magazine (Site not responding. Last check: 2007-11-07)
		Accordingly, WGS 84 is widely used for "absolute" positioning activities whereby people assume that satellite orbits are sufficiently accurate to serve as the sole source of control for positioning points of interest.
		The origin, orientation, and scale of WGS 84 (G873) are determined relative to adopted positional coordinates for 15 GPS tracking stations: five of them are maintained by the Air Force and ten by NIMA (see Fig.
		Regarding the WGS 84 reference system, it is generally assumed that WGS 84 (original) is identical to NAD 83 (1986), that WGS 84 (G730) is identical to ITRF92, and that WGS 84 (G873) is identical to ITRF96.
	www.profsurv.com /newpsm/archive.php?issue=40&article=561 (2205 words)

	USGS (U.S. Geological Survey) EROS, Sioux Falls, SD
		The WGS 72 datum was the result of an extensive effort extending over approximately three years to collect selected satellite, surface gravity, and astrogeodetic data available throughout 1972.
		The WGS 84 datum was developed as a replacement for WGS 72 by the military mapping community as a result of new and more accurate instrumentation and a more comprehensive control network of ground stations.
		Applies only when proceeding directly from WGS 72 coordinates to WGS 84 coordinates; does not contain the effect of the WGS 84 Earth gravitational model and geoid, nor the effect of local geodetic system-to-WGS 84 datum shifts being better than local geodetic system-to-WGS 72 datum shifts.
	edc.usgs.gov /guides/glossary/u_z.html (733 words)

	Survey of India - Press Release (Site not responding. Last check: 2007-11-07)
		He also said that all efforts are being made to generate maps of other parts of the country on WGS 84 datum, and SoI will keep on releasing maps when they are ready.
		Amitabha Pande (the man considered to be architect of dual series of maps in India), joint secretary, Department of Science and Technology, perceived the event as a demonstration of a sea change in the attitude of SoI, an organization that is not habitual to provide information in the public domain.
		Commenting on the occasion, Mukund Rao from Indian Space Research Organisation said, "Release of the WGS 84 series of maps in digital format is a welcome step." He appreciated the initiative as a pragmatic step to meet the user requirements.
	www.geoplace.com /pressrelease/pressdetail_print.asp?id=3755 (738 words)

	Built In Coordinate System Components
		The reference frame at which these parameters are zero is WGS 84.
		The parameters are also expressed as a measurement from the reference frame (WGS 84) to the frame being described.
		The dx, dy, and dz parameters provide the origin of this frame in meters within the WGS 84 frame.
	www.openspirit.com /OpenSpirit_Tech_Docs/v2.5.0/docs/Development/ClientReferences/BuiltInCSComps.html (167 words)

	Definition of WGS 84 GPS World - Find Articles (Site not responding. Last check: 2007-11-07)
		The latest least-square solution of the WGS 84 (G1150) to establish the positions of the GPS tracking stations is statistically incorrect.
		NGA maintains and periodically updates the state-of-the-art WGS 84 model in an open and collaborative environment.
		NGA is hurting the geodetic accuracy of GPS positioning by sticking to the wrongly defined WGS 84.
	www.findarticles.com /p/articles/mi_m0BPW/is_2_16/ai_n13255493 (470 words)

	Chapter 4
		These projections are being replaced by the WGS and will be phased out once the maps have been reprinted with the WGS.
		Thus, for that portion of the world where the UTM grid is specified (80° south to 84° north), the UTM grid-zone number is the first element of a military grid reference.
		The letters A, B, Y, and Z are used only in the polar regions, and their presence in an MGRS (with the omission of a zone number) designates that the coordinates are UPS.
	www.globalsecurity.org /military/library/policy/army/fm/3-34-331/ch4.htm (2663 words)

	Q&A (Site not responding. Last check: 2007-11-07)
		This can be the GRS 80 ellipsoid, or a new ellipsoid with the same parameters as WGS 84 as shown.
		* Entering WGS 84 as the ellipsoid here, and using a geoid model based on WGS 84 will cause the orthometric heights to be calculated from the WGS 84 ellipsoid heights from the SPP or HERE position of the base and not the transformed ellipsoid heights.
		This system will contain a shift from the approximate WGS 84 coordinates produced from the base, to the true WGS 84 coordinates of State Plane point.
	www.ellisv.com /qna8.html (1286 words)

	[No title]
		They may be based on local datums which were defined for surveying purposes at the time, but whose relationship to the recently developed WGS 84 Datum has not been established or investigated.
		This presents the opportunity of improving the positional accuracy of charts in general and, more specifically, establishing a relationship with WGS 84 Datum where this is unknown.
		It is unrealistic to expect that a series of reported WGS 84 positions relating to a given chart will enable it to be referenced to that datum with the accuracy required for geodetic purposes.
	www.ukho.gov.uk /amd/h102b.asp (709 words)

	P1041 - FUSING LIDAR AND IFSAR DEMS: A SEVEN-STEP METHODOLOGY
		WGS 84 (orig.) and NAD 83 (86) can be considered identical for most purposes.
		In Table 2, WGS 84 (orig.) and NAD 83 (86) are identical horizontally and only slightly different when looking at the flattening coefficient of the ellipsoid models of WGS 84 and GRS 80 (Milbert, D. and GDA Technical Manual).
		The new WGS 84 reference frames WGS 84 (G730) and WGS 84 (G873) are not supported within a GIS because of the vertical component being based on ITRF.
	gis.esri.com /library/userconf/proc02/pap1041/p1041.htm (9122 words)

	Point of Beginning Message Board - Messages View
		In trying to use GRS 80 in their computations the DOD originally introduced a very tiny error, so that their ellipsoid, what might be called the WGS 84 ellipsoid, differs from the GRS 80 ellipsoid by an amount that is so small as to be unnoticable to a user.
		Coordinates truly referenced to the WGS 84 coordinate system would be 3 to 6 feet different than the NAD 83 coordinates that the software produces.
		Now that we have arrived at a time when it is possible to get very accurate WGS 84 coordinates, I guess they don't want to admit that their written material is wrong and has been for a number of years, so they just put their head in the sand and hope it will go away.
	www.i-boards.com /bnp/pob/messages.asp?MsgID=217339&ThreadID=21931&IsResponse=False (1560 words)

	SOME QUESTIONS ON DATUMS AND DATUM TRANSFORMATIONS
		WGS 84 (G730) Epoch 1994.0 Used by DMA from 0000 UTC January 2, 1994, until 2400 UTC September 28, 1996 (Realignment of WGS 84 to ITRF 91 using GPS at GPS Week 730).
		WGS 84 (G873) Epoch 1997.0 Used by NIMA (formerly DMA) from 0000 UTC September 29, 1996, until the present (realignment of WGS 84 [G730] to ITRF 94).
		WGS 84 coordinates are transformed and displayed in whatever datum you choose.
	www2.arnes.si /~gljsentvid10/datm_faq.html (6465 words)

	FUSING LIDAR AND IFSAR DEMS: A SEVEN-STEP METHODOLOGY (Site not responding. Last check: 2007-11-07)
		In Table 2, WGS 84 (orig.) and NAD 83 (86) are identical horizontally and only slightly different when looking at the flattening coefficient of the ellipsoid models of WGS 84 and GRS 80 (Milbert and GDA Technical Manual).
		As describe Milbert (personnel communications), the relationship between WGS 84, ITRF, and NAD 83 for the United States is seen in Table 4.
		The new WGS 84 reference frames WGS 84 (G730), WGS 84 (G873), and WGS 84 (G1150) are not supported within a GIS because of the vertical component being based on ITRF.
	www.tec.army.mil /publications/fusing/p1041.html (9464 words)

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