“Undulation of the geoid”的意思、由来-开放百科全书

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Undulation of the geoid

释义

References

Undulation of the geoid is the height of the geoid relative to a given ellipsoid of reference. In maps and common use the height over the mean sea level (such as orthometric height) is used to indicate the height of elevations while the ellipsoidal height results from the GPS system.

The process of the undulation is not standardised, as different countries use different mean sea levels as reference but most commonly refers to the EGM96 geoid. Calculating the undulation factor is mathematically challenging. This is why many handheld GPS receivers have built-in undulation lookup tables^[1] to determine the height above sea level.

The deviation between the ellipsoidal height and the orthometric height can be calculated by

Likewise, the deviation between the ellipsoidal height and the normal height can be calculated by

Geoid undulations display uncertainties which can be estimated by using several methods, e.g. least-squares collocation (LSC), fuzzy logic, artificial neutral networks, radial basis functions (RBF), and geostatistical techniques. Geostatistical approach has been defined as the most improved technique in prediction of geoid undulation.^[2]

References

1. ^{{cite web|last1=Wormley|first1=Sam|title=GPS Orthometric Height|url=http://www.edu-observatory.org/gps/height.html|website=www.edu-observatory.org|accessdate=15 June 2016|deadurl=yes|archiveurl=https://web.archive.org/web/20160620102914/http://www.edu-observatory.org/gps/height.html|archivedate=20 June 2016|df=}}
2. ^{{Cite journal|last=Chicaiza|first=E.G.|last2=Leiva|first2=C.A.|last3=Arranz|first3=J.J.|last4=Buenańo|first4=X.E.|date=2017-06-14|title=Spatial uncertainty of a geoid undulation model in Guayaquil, Ecuador|url=https://www.degruyter.com/view/j/geo.2017.9.issue-1/geo-2017-0021/geo-2017-0021.xml?format=INT|journal=Open Geosciences|volume=9|issue=1|pages=255-265|doi=10.1515/geo-2017-0021|issn=2391-5447|via=|bibcode=2017OGeo....9...21C}}

{{cite web|title=CHAPTER V PHYSICAL GEODESY|url=http://www.ngs.noaa.gov/PUBS_LIB/Geodesy4Layman/TR80003C.HTM|website=www.ngs.noaa.gov|publisher=NOAA|accessdate=15 June 2016}}
{{cite web|title=Geoid Height Calculator {{!}} Software {{!}} UNAVCO|url=http://www.unavco.org/software/geodetic-utilities/geoid-height-calculator/geoid-height-calculator.html|website=www.unavco.org|publisher=Unavco|accessdate=15 June 2016}}

4 : Geodesy|Global Positioning System|Gravimetry|Vertical position

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