Talk:World Geodetic System

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This text is taken from the public domain resource Geodesy for the Layman at http://www.ngs.noaa.gov/PUBS_LIB/Geodesy4Layman/TR80003E.HTM#ZZ11 -- please Wikify as necessary. This document was written in 1984 and may need to be updated.

Ellpsoids not Geoids?

Aren't these all ellipsoids and not geoids? These WGSxx ellipsoids seem like the best fitting ellipsoids for the geoids, but they are still theoretical surfaces and not gravity based. DavidForrest 01:56, 4 April 2006 (UTC)

The WGS84 and EGM96 define both an ellipsoid and a geoid, with the ellipsoids essentially "first order" geoids. The EGM96 geoid is definitely gravity based. Unfortunately, the ellipsoid was not changed from the earlier WGS84 parameters because this would have seriously impacted the operation of GPS. MFago 14:05, 4 April 2006 (UTC)

geodetic system == geodetic datum, need to clatify that. The word "datum" is used in GPS geceivers, so it is very important.

[edit] EGM06

"This new model will have a geoid with a resolution approaching 10 km, requiring over 4.6 million terms in the spherical expansion (versus 130,317 in EGM96 and 32,757 in WGS 84)."

The resolution of 10 km is wrong. Perhaps it is 10 cm? Also, it would be good to include the maximum spherical harmonic degree of the EGM96 and EGM06 models (360 vs. 2160?). Lunokhod 19:44, 13 November 2006 (UTC)

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