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The use of gravity data to determine orthometric heights at the Hong Kong territories / Albertini Nsiah Ababio in Journal of applied geodesy, vol 16 n° 4 (October 2022)  

Public [article]  inJournal of applied geodesy > vol 16 n° 4 (October 2022) . - pp 401 - 416 Titre : The use of gravity data to determine orthometric heights at the Hong Kong territories Type de document : Article/Communication Auteurs : Albertini Nsiah Ababio, Auteur ; Robert Tenzer, Auteur Année de publication : 2022 Article en page(s) : pp 401 - 416 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] altitude orthométrique [Termes IGN] correction orthométrique [Termes IGN] Hong-Kong [Termes IGN] interpolation [Termes IGN] levé gravimétrique [Termes IGN] montagne [Termes IGN] système de référence local [Vedettes matières IGN] Altimétrie Résumé : (auteur) The Hong Kong Principal Datum (HKPD) is the currently adopted official geodetic vertical datum at the Hong Kong territories. The HKPD is practically realized by heights of levelling benchmarks. The HKPD heights are, however, neither normal nor orthometric. The reason is that heights of levelling benchmarks were determined from precise levelling measurements, but without involving gravity observations along levelling lines. To reduce systematic errors due to disregarding the gravity information along levelling lines, we used terrestrial and marine gravity data to interpolate gravity values at levelling benchmarks in order to compute and apply the orthometric correction to measured levelling height differences. Our results demonstrate the importance of incorporating the gravity information even for a relatively small region but characterized by a rough topography with heights of levelling benchmarks exceeding several hundreds of meters. According to our estimates, the orthometric correction reaches (and even slightly exceeds) ±2 cm, with maxima along levelling lines crossing mountain chains. Numéro de notice : A2022-742 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/jag-2022-0012 Date de publication en ligne : 04/08/2022 En ligne : https://doi.org/10.1515/jag-2022-0012 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101724 [article]

Adaptive block modeling of time dependent variations of datum reference points in a tectonically active area / Chun-Yun Chou in Survey review, vol 54 n° 386 (September 2022)  

Public [article]  inSurvey review > vol 54 n° 386 (September 2022) . - pp 404 - 419 Titre : Adaptive block modeling of time dependent variations of datum reference points in a tectonically active area Type de document : Article/Communication Auteurs : Chun-Yun Chou, Auteur ; Jen-Yu Han, Auteur Année de publication : 2022 Article en page(s) : pp 404 - 419 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] analyse de groupement [Termes IGN] angle d'Euler [Termes IGN] champ de vitesse [Termes IGN] Cinématique [Termes IGN] collocation par moindres carrés [Termes IGN] données GNSS [Termes IGN] formule d'Euler [Termes IGN] matrice de covariance [Termes IGN] rotation [Termes IGN] série temporelle [Termes IGN] station GNSS [Termes IGN] système de référence local [Termes IGN] Taïwan [Termes IGN] tectonique des plaques [Termes IGN] variation temporelle Résumé : (auteur) Although a dynamic or semi-dynamic datum has been adopted in some countries, it remains a challenge if a long-term stable datum is to be established in a tectonic active area. This study presents an approach to realistically reflect the time dependent behaviors of ground reference points while maintaining the long-term stability of a datum. An adaptive approach coupled with the Euler motion model is proposed for dividing an area into blocks. A least-squares collocation is then applied for modeling the residual velocities in each block. A case study using the data from 375 continuously operated GNSS stations in Taiwan is presented. It is illustrated that the complex surface kinematics in this region can be divided into three blocks. Significant reductions up to 64% of residual velocities were obtained. This shows that a stable datum can be established in a region with active and complicated surface kinematics by implementing the proposed. Numéro de notice : A2022-658 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2021.1949194 Date de publication en ligne : 12/07/2021 En ligne : https://doi.org/10.1080/00396265.2021.1949194 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101509 [article]

Mise à jour du registre de l’EPSG suite aux évolutions du RGF93 / Thierry Gattacceca in XYZ, n° 170 (mars 2022)

Public [article]  inXYZ > n° 170 (mars 2022) . - pp 23 - 26 Titre : Mise à jour du registre de l’EPSG suite aux évolutions du RGF93 Type de document : Article/Communication Auteurs : Thierry Gattacceca, Auteur Année de publication : 2022 Projets : 1-Pas de projet / Article en page(s) : pp 23 - 26 Langues : Français (fre) Descripteur : [Vedettes matières IGN] Géodésie [Termes IGN] grille de conversion altimétrique [Termes IGN] qualité des données [Termes IGN] repère de référence [Termes IGN] réseau géodésique français 1993 [Termes IGN] synchronisation [Termes IGN] système de référence géodésique Résumé : (Auteur) L’IGN maintient un registre (IGNF) consacré aux références géodésiques françaises. En parallèle, l’IGN alimente le “registre géodésique” EPSG, devenu un standard de fait dans ce domaine. Les récentes évolutions du RGF93 ont entraîné une remise en question de la présentation de ce système de référence géodésique dans les registres, avec des impacts potentiellement significatifs pour les utilisateurs. Numéro de notice : A2022-224 Affiliation des auteurs : IGN (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtSansCL DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100190 [article]

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Evaluation of methods for connecting InSAR to a terrestrial reference frame in the Latrobe Valley, Australia / P.J. Johnston in Journal of geodesy, vol 95 n° 10 (October 2021)  

Public [article]  inJournal of geodesy > vol 95 n° 10 (October 2021) . - n° 115 Titre : Evaluation of methods for connecting InSAR to a terrestrial reference frame in the Latrobe Valley, Australia Type de document : Article/Communication Auteurs : P.J. Johnston, Auteur ; M. S. Filmer, Auteur ; Thomas Fuhrmann, Auteur Année de publication : 2021 Article en page(s) : n° 115 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] Australian Geodetic Datum [Termes IGN] Australie [Termes IGN] Continuously Operating Reference Station network [Termes IGN] image Sentinel-SAR [Termes IGN] incertitude de mesurage [Termes IGN] interféromètrie par radar à antenne synthétique [Termes IGN] International Terrestrial Reference Frame [Termes IGN] littoral [Termes IGN] propagation d'erreur [Termes IGN] réseau géodésique permanent [Termes IGN] station GNSS [Termes IGN] subsidence Résumé : (auteur) Deformation measurements from satellite-borne synthetic aperture radar interferometry (InSAR) are usually measured relative to an arbitrary reference point (RP) of assumed stability over time. For InSAR rates to be reliably interpreted as uplift or subsidence, they must be connected to a defined Earth-centred terrestrial reference frame (TRF), usually made through GNSS continuously operating reference stations (CORS). We adapt and compare three methods of TRF connection proposed by different studies which we term the single CORS RP (SCRP), plane-fit multiple CORS (PFMC), and the multiple CORS RP (MCRP). We generalise equations for these methods, and importantly, develop equations to propagate InSAR and GNSS uncertainties through the transformation process. This is significant, because it is important to not only estimate the InSAR uncertainties, but also to account for the uncertainties that are introduced when connecting to the CORS so as to better inform our interpretation of the deformation field and the limitation of the measurements. We then test these methods using Sentinel-1 data in the Latrobe Valley, Australia. These results indicate that differences among the three TRF connection methods may be greater than their estimated uncertainties. MCRP appears the most reliable method, although it may be limited in large study areas with sparse CORS due to long wavelength InSAR errors and that gaps and/or steps may appear at the spatial limit from the CORS. SCRP relies on the quality of the single CORS connection, but can be validated by unconnected CORS in the study area. The PFMC method is suited to larger areas undergoing slow, constant deformation covering large spatial extents where there are evenly distributed CORS across the study area. Selecting an optimal method of TRF connection is dependent on local site conditions, CORS network geometry and the characteristics of the deformation field. Hence, the choice of TRF connection method should be carefully considered, because different methods may result in significantly different transformed deformation rates. We confirm slow subsidence across the Latrobe Valley relative to the vertical component of the ITRF2014, with localised high subsidence rates near open cut mining activities. Subsidence of ~ -6 mm/year is observed in the adjacent coastal region which may exacerbate relative sea level rise along the coastline, increasing future risks of coastal inundation. Numéro de notice : A2021-749 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s00190-021-01560-2 Date de publication en ligne : 08/10/2021 En ligne : https://doi.org/10.1007/s00190-021-01560-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98730 [article]

Establishing vertical separation models for vulnerable coastlines in developing territories / Cassandra Nanlal in Marine geodesy, vol 44 n° 5 (September 2021)  

Public [article]  inMarine geodesy > vol 44 n° 5 (September 2021) . - pp 387 - 407 Titre : Establishing vertical separation models for vulnerable coastlines in developing territories Type de document : Article/Communication Auteurs : Cassandra Nanlal, Auteur ; Keith Miller, Auteur ; Dexter Davis, Auteur ; Michael Sutherland, Auteur Année de publication : 2021 Article en page(s) : pp 387 - 407 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] aménagement du littoral [Termes IGN] Amérique du sud [Termes IGN] changement climatique [Termes IGN] données altimétriques [Termes IGN] géodésie physique [Termes IGN] golfe [Termes IGN] hauteurs de mer [Termes IGN] niveau de la mer [Termes IGN] simulation hydrodynamique [Termes IGN] système de référence altimétrique [Termes IGN] système de référence local [Termes IGN] trait de côte [Termes IGN] vulnérabilité Résumé : (Auteur) Vertical separation models are valuable for coastal zone management and protection against the effects of climate change. To date, the development of such models has been undertaken in areas where long-term sea level measurements exist and there are resources for extensive offshore bathymetric and Global Navigation Satellite Systems surveys. Many small island developing states and other resource constrained territories host vulnerable coastal zones and would benefit from such models, however, financial constraints and data sparsity make it difficult. This article describes the establishment of a vertical separation model using an amalgamation of long- and short-term sea level measurements with hydrodynamic modeling. With existing vertical separations at only two coastal points for comparison, the model was designed to include a tidal prediction element which allowed for validation against sparse independently observed sea levels. Considering that unmodeled influences on sea levels in the study area can exceed 0.2 m at times, the method was tested against independently observed sea levels and can be considered successful with variances in the range of 1.3–4.5% of the average tidal range for the study area. This research provides the means of addressing a significant need in developing territories where long-term sea level records are unavailable and resource deficiencies exist. Numéro de notice : A2021-576 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01490419.2020.1844825 Date de publication en ligne : 02/12/2020 En ligne : https://doi.org/10.1080/01490419.2020.1844825 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98227 [article]

La nouvelle grille de conversion altimétrique RAF18b / François L'écu in XYZ, n° 167 (juin 2021)

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Le RGF93v2b : une nouvelle réalisation du RGF93 / Romain Fagès in XYZ, n° 167 (juin 2021)

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Positional uncertainty of network RTK observations in a modern datum / T. Bernstein in Journal of geodetic science, vol 11 n° 1 (January 2021)  

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The influence of sea-level changes on geodetic datums along the east coast of China / Yang Liu in Marine geodesy, vol 44 n° 1 (January 2021)  

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CORS usage for GPS survey in the greater accra region: Advantages, limitation, and suggested remedies / Sebastian Botsyo in Journal of Geovisualization and Spatial Analysis, vol 4 n° 2 (December 2020)  

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Rethinking error estimations in geospatial data: the correct way to determine product accuracy / Qassim Abdullah in Photogrammetric Engineering & Remote Sensing, PERS, vol 86 n° 7 (July 2020)  

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Triangulation network of 1929–1944 of the first 1:500 urban map of València / Miriam Villar-Cano in Survey review, vol 52 n° 373 (July 2020)  

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Les États-Unis remplacent le NAD83 par le NATRF2022 : ce que cela signifie pour le Canada / Caroline Erickson in Geomatica [en ligne], vol 74 n° 1 (Mars 2020)  

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Impact of network constraining on the terrestrial reference frame realization based on SLR observations to LAGEOS / Radoslaw Zajdel in Journal of geodesy, vol 93 n°11 (November 2019)  

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Transformation 3D des coordonnées GPS en coordonnées Nord Sahara avec la MRE / Medjahed Sid Ahmed in Géomatique expert, n° 130-131 (octobre - décembre 2019)

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