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Assessment of ArcGIS based extraction of geoidal undulation compared to National Geospatial Intelligence Agency (NGA) model – A case study / Sher Muhammad in Journal of applied geodesy, vol 14 n° 1 (January 2020)  

Public [article]  inJournal of applied geodesy > vol 14 n° 1 (January 2020) . - pp 77 - 81 Titre : Assessment of ArcGIS based extraction of geoidal undulation compared to National Geospatial Intelligence Agency (NGA) model – A case study Type de document : Article/Communication Auteurs : Sher Muhammad, Auteur ; Lide Tian, Auteur Année de publication : 2020 Article en page(s) : pp 77 - 81 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] altitude orthométrique [Termes IGN] détection d'erreur [Termes IGN] Earth Gravity Model 1996 [Termes IGN] ellipsoïde (géodésie) [Termes IGN] géoïde altimétrique [Termes IGN] Himalaya [Termes IGN] interpolation [Termes IGN] Matlab [Termes IGN] modèle numérique de surface [Termes IGN] niveau moyen des mers [Termes IGN] Tibet Résumé : (auteur) Global Navigation Satellite System (GNSS) and remote sensing Digital Elevation Models (DEMs) represent earth’s surface elevation with reference to ellipsoid and orthometric heights. Proper estimation of the geoid (difference of ellipsoid and orthometric heights) is necessary before comparing data referenced to the different vertical datum. In this paper, an error in estimating EGM96 orthometric height is highlighted, verified by NGA/NASA developed model and MATLAB®. A significant error was found in the ArcGIS derived EGM96 orthometric heights range between ±6.9 meters. In addition, interpolation of low-resolution geoid data also produces significant biases depending on geographic location and the number of the interpolation data point. The bias was maximum negative in the central part of Tibetan Plateau and Himalaya. Therefore, estimation of orthometric height similar to NGA/NASA model precision is necessary for comparison of DEMs for natural resources management, 3D modelling and glaciers mass balance mainly in the mountainous regions. Numéro de notice : A2020-041 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jag-2019-0030 En ligne : https://doi.org/10.1515/jag-2019-0030 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94512 [article]

The Canadian Geodetic Vertical Datum of 2013 (CGVD2013) / Marc Véronneau in Geomatica [en ligne], vol 70 n° 1 (March 2016)  

Public [article]  inGeomatica [en ligne] > vol 70 n° 1 (March 2016) . - pp 9 - 19 Titre : The Canadian Geodetic Vertical Datum of 2013 (CGVD2013) Type de document : Article/Communication Auteurs : Marc Véronneau, Auteur ; Jianliang Huang, Auteur Année de publication : 2016 Article en page(s) : pp 9 - 19 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] Canada [Termes IGN] géoïde altimétrique [Termes IGN] géoïde gravimétrique [Termes IGN] géoïde local [Termes IGN] mise à jour [Termes IGN] nivellement [Termes IGN] positionnement par GNSS [Termes IGN] repère de nivellement [Termes IGN] système de référence géodésique [Termes IGN] système de référence local Résumé : (auteur) The Canadian Geodetic Vertical Datum of 2013 (CGVD2013) is the first major update to the vertical datum in Canada in almost 100 years. Canada is not only moving to a new vertical datum, but it is also using a modernized approach to realize it. The modernization of the height reference system is necessary to make it compatible with Global Navigation Satellite System (GNSS), which is commonly used for positioning by a growing number of users across Canada and the world. The geodetic levelling technique, which established a nation-wide network of benchmarks with known elevations, is replaced by a geoid model that describes the vertical datum with respect to an ellipsoid, which is the reference surface for GNSS positioning. Technically, height modernization replaces the need for the maintenance of benchmarks, as users can now install their own markers at more convenient locations using GNSS. The current geoid model for CGVD2013 is the Canadian Gravimetric Geoid 2013 (CGG2013. Numéro de notice : A2016-432 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.5623/cig2016-101 En ligne : https://doi.org/10.5623/cig2016-101 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81329 [article]

The height datum problem and the role of satellite gravity models / A. Gatti in Journal of geodesy, vol 87 n° 1 (January 2013)  

Public [article]  inJournal of geodesy > vol 87 n° 1 (January 2013) . - pp 15 - 22 Titre : The height datum problem and the role of satellite gravity models Type de document : Article/Communication Auteurs : A. Gatti, Auteur ; M. Reguzzoni, Auteur ; Giovanna Venuti, Auteur Année de publication : 2013 Article en page(s) : pp 15 - 22 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] altitude normale [Termes IGN] anomalie de pesanteur [Termes IGN] données GOCE [Termes IGN] données GRACE [Termes IGN] Earth Gravity Model 2008 [Termes IGN] erreur en altitude [Termes IGN] erreur systématique [Termes IGN] géoïde altimétrique [Termes IGN] hauteur ellipsoïdale [Termes IGN] modèle de géopotentiel [Termes IGN] niveau moyen des mers [Termes IGN] réseau de nivellement [Termes IGN] système de référence altimétrique Résumé : (Auteur) Regional height systems do not refer to a common equipotential surface, such as the geoid. They are usually referred to the mean sea level at a reference tide gauge. As mean sea level varies (by +1 to 2 m) from place to place and from continent to continent each tide gauge has an unknown bias with respect to a common reference surface, whose determination is what the height datum problem is concerned with. This paper deals with this problem, in connection to the availability of satellite gravity missions data. Since biased heights enter into the computation of terrestrial gravity anomalies, which in turn are used for geoid determination, the biases enter as secondary or indirect effect also in such a geoid model. In contrast to terrestrial gravity anomalies, gravity and geoid models derived from satellite gravity missions, and in particular GRACE and GOCE, do not suffer from those inconsistencies. Those models can be regarded as unbiased. After a review of the mathematical formulation of the problem, the paper examines two alternative approaches to its solution. The first one compares the gravity potential coefficients in the range of degrees from 100 to 200 of an unbiased gravity field from GOCE with those of the combined model EGM2008, that in this range is affected by the height biases. This first proposal yields a solution too inaccurate to be useful. The second approach compares height anomalies derived from GNSS ellipsoidal heights and biased normal heights, with anomalies derived from an anomalous potential which combines a satellite-only model up to degree 200 and a high-resolution global model above 200. The point is to show that in this last combination the indirect effects of the height biases are negligible. To this aim, an error budget analysis is performed. The biases of the high frequency part are proved to be irrelevant, so that an accuracy of 5 cm per individual GNSS station is found. This seems to be a promising practical method to solve the problem. Numéro de notice : A2013-070 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-012-0574-3 Date de publication en ligne : 03/07/2012 En ligne : https://doi.org/10.1007/s00190-012-0574-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32208 [article]

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Tuning a gravimetric quasigeoid to GPS-levelling by non-stationary least-squares collocation / N. Darbehesti in Journal of geodesy, vol 84 n° 7 (July 2010)  

Public [article]  inJournal of geodesy > vol 84 n° 7 (July 2010) . - pp 419 - 431 Titre : Tuning a gravimetric quasigeoid to GPS-levelling by non-stationary least-squares collocation Type de document : Article/Communication Auteurs : N. Darbehesti, Auteur ; Will E. Featherstone, Auteur Année de publication : 2010 Article en page(s) : pp 419 - 431 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] appariement de données localisées [Termes IGN] collocation par moindres carrés [Termes IGN] géoïde altimétrique [Termes IGN] géoïde gravimétrique [Termes IGN] géoïde local [Termes IGN] nivellement par GPS [Termes IGN] Perth Résumé : (Auteur) This paper addresses implementation issues in order to apply non-stationary least-squares collocation (LSC) to a practical geodetic problem: fitting a gravimetric quasigeoid to discrete geometric quasigeoid heights at a local scale. This yields a surface that is useful for direct GPS heighting. Non-stationary covariance functions and a non-stationary model of the mean were applied to residual gravimetric quasigeoid determination by planar LSC in the Perth region of Western Australia. The non-stationary model of the mean did not change the LSC results significantly. However, elliptical kernels in non-stationary covariance functions were used successfully to create an iterative optimisation loop to decrease the difference between the gravimetric quasigeoid and geometric quasigeoid at 99 GPS-levelling points to a user-prescribed tolerance. Numéro de notice : A2010-301 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0377-3 Date de publication en ligne : 18/04/2010 En ligne : https://doi.org/10.1007/s00190-010-0377-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30495 [article]

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Preliminary works on creation of the new geoid model HRG2009 / I. Grgic (01/01/2010)

Public contenu dans Second proceedings of the Croatian Geodetic Institute for the period 2006-2009 / Croatian geodetic institute (2010) Titre : Preliminary works on creation of the new geoid model HRG2009 Type de document : Article/Communication Auteurs : I. Grgic, Auteur ; M. Lucic, Auteur ; Marija Repanic, Auteur ; et al., Auteur Editeur : Zagreb [Croatie] : Croatian geodetic institute Année de publication : 01/01/2010 Conférence : CGI 2009, 2nd proceedings of the Croatian Geodetic Institute for the period 2006-2009 Zagreb Croatie Importance : pp 303 - 312 Note générale : Bibliographie Langues : Anglais (eng) Serbo-croate (Latin) (scr) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] Croatie [Termes IGN] géoïde altimétrique [Termes IGN] géoïde local [Termes IGN] nivellement [Termes IGN] positionnement par GNSS Résumé : (Auteur) The official Croatian geoid model HRG2000 was developed as a surface for con--version of GNSS-derived ellipsoidal heights into orthometric heights. CROatian POsitionig System (CROPOS), based on 30 permanently working GNSS reference station, had been esta-blished last year. Since HRG2000 geoid model characterizes some weaknesses regarding abso-lute orientation we have used CROPOS service to define new points which will be a base for creation of the new Croatian geiod model HRG2009. For this purpose over the whole Croatian territory more than 500 GNSS/levelling geodetic points were stabilized and measured according to the approximate raster of10x10km. All measured points were connected to the nearest ben-chmarks of the new Croatian vertical datum by precise levelling. The GNSS/Levelling survey provides reliable geoid undulation but only at the points where the survey is made. Therefore for the construction of an accurate HRG2009 geoid model afterwards the gravimetric geo-id model, which should be calculated from all new measured gravity points and old availa-ble gravity data, will befitted to the geoid undulation data from a GNSS/levelling survey. The recently determined geoid undulation calculated from GNSS/Levelling data at the measured geodetic points were analyzed additionally in relation to the geoid undulation from the geoid model HRG2000. The range of geoid undulation and orthometric height differences at measu-red points between old and new geoid model shows an important progress concerning quality in definition of heights for the Republic of Croatia. Numéro de notice : C2009-014 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Communication Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=65054

Sea surface topography and marine geoid by airborne laser altimetry and shipborne ultrasound altimetry / Philippe Limpach (2010)  

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Les marées terrestres, la dynamique du manteau et la sismicité / Laurent Métivier in Géomatique expert, n° 67 (01/02/2009)

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Conversion altimétrique des hauteurs ellipsoïdales par GPS / A. Zeggai in XYZ, n° 109 (décembre 2006 - février 2007)

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What does height really mean? Part 4 GPS heighting / Thomas H. Meyer in Surveying and land information science, vol 66 n° 3 (01/09/2006)

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The African Geoid Project: establishing a vertical reference / C. Merry in Geoinformatics, vol 7 n° 7 (01/11/2004)

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Assessment of the new national geoid height model, GEOID03 / D.R. Roman in Surveying and land information science, vol 64 n° 3 (01/09/2004)

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Mise en place d'un SIG pour la gestion du contrôle qualité de la grille de référence des altitudes françaises RAF 98 = [mémoire de] Projet de fin d'études, Universitatea Tehnica de Constructii Bucuresti UTCB / P.D. Dumitru (2004)

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Instrument of GRACE: GPS augments gravity measurements / C. Dunn in GPS world, vol 14 n° 2 (February 2003)

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A new Canadian geoid model in support of levelling by GPS / G. Fotopoulos in Geomatica, vol 54 n° 1 (March 2000)

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Alongtrack-/Crossover-Verfahren und Spektralanalyse zur Trennung geodätisch-geophysikalischer Signale in Altimeterdaten / R. Stubenvoll (2000)

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