Science Fair Project Encyclopedia
Geodetic system
(Redirected from Map datum)
Geodesy
Geodetic systems or map datums are used in geodesy, navigation, surveying and the Global Positioning System to indicate the datum or reference point to which a measured position is relative.
The systems are needed because the earth is not a perfect sphere.
Examples of map datums are:
- WGS 84, 72, 64 and 60 of the World Geodetic System
- OSGB36 of the Ordnance Survey of Great Britain
- ED50 : the European Datum
The main reason that there are a number of datums is that national map making organisations did not have a common surveying reference point and only produced maps for their locality.
Last updated: 08-30-2005 05:12:56
03-10-2013 05:06:04
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The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details