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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)  

Public [article]  inMarine geodesy > vol 44 n° 1 (January 2021) . - pp 26 - 41 Titre : The influence of sea-level changes on geodetic datums along the east coast of China Type de document : Article/Communication Auteurs : Yang Liu, Auteur ; Chuanyin Zhang, Auteur ; Baogui Ke, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : pp 26 - 41 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes descripteurs IGN] analyse harmonique [Termes descripteurs IGN] champ de pesanteur terrestre [Termes descripteurs IGN] changement du niveau de la mer [Termes descripteurs IGN] Chine [Termes descripteurs IGN] déformation de la croute terrestre [Termes descripteurs IGN] données géodésiques [Termes descripteurs IGN] données spatiotemporelles [Termes descripteurs IGN] fonction de Green [Termes descripteurs IGN] littoral [Termes descripteurs IGN] surveillance du littoral [Termes descripteurs IGN] système de référence local Résumé : (Auteur) Non-tidal variation on sea level generates immediate changes in gravity field and deformation of the Earth’s crust, thus influencing the stability of geodetic datums. To achieve higher accuracy of geodetic datums in coastal and island areas, sea-level changes should be adequately considered when conducting the maintenance of datums. Based on the data of sea-level anomalies from 2014 to 2017 and the theory of load-deformation of elastic spherical earth, this paper demonstrates that impacts of non-tidal ocean load can be quantitatively calculated on geodetic datums along the east coast of China, by using removerestore technique and combining spherical harmonic analysis of gravity field and Green’s functions to calculate loads. Temporal and spatial analyses on the impacts are conducted with Continuously Operating Reference Stations (CORS) sites along the coast and on the islands. This paper has drawn some conclusions as follows: (1) The impact of non-tidal ocean loads on the east coastal geoid ranges from ?4.16 to 4.17mm, that on ground gravity ranges from ?15.44 to 17.02 some conclusions as follows: (1) The impact oranges from ?7.55 to 6.69mm. (2) The impacts are dominated by annual and semi-annual cycles. (3) The impacts appear to be more prominent in coastal areas and on islands than in inland areas. Numéro de notice : A2021-058 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01490419.2020.1835757 date de publication en ligne : 06/11/2020 En ligne : https://doi.org/10.1080/01490419.2020.1835757 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96847 [article]

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)  

Public [article]  inJournal of Geovisualization and Spatial Analysis > vol 4 n° 2 (December 2020) . - n° 20 Titre : CORS usage for GPS survey in the greater accra region: Advantages, limitation, and suggested remedies Type de document : Article/Communication Auteurs : Sebastian Botsyo, Auteur ; Bernard Borketey Bortei, Auteur ; John Ayer, Auteur Année de publication : 2020 Article en page(s) : n° 20 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes descripteurs IGN] balise [Termes descripteurs IGN] géopositionnement [Termes descripteurs IGN] Ghana [Termes descripteurs IGN] International Terrestrial Reference Frame [Termes descripteurs IGN] positionnement statique [Termes descripteurs IGN] station de référence [Termes descripteurs IGN] station permanente [Termes descripteurs IGN] système de référence local Résumé : (auteur) The use of Continuously Operating Reference Stations (CORS) enables surveyors to differentially correct static Global Positioning System (GPS) measurements. CORS are designed to support the broad spectrum of post-processed, relative GPS techniques, and applications. Enhancing geospatial positioning applications of CORS data involves the critical role in defining the nation’s geodetic reference system. With the establishment of a coordinated system of CORS, an Online Positioning User Service can become available for processing in single positioning mode to provide corresponding accurate and homogeneous positional coordinates. The Survey and Mapping Division (SMD), Lands Commission of Ghana, has established four CORS in the Greater Accra, and Ashanti, Western and Brong-Ahafo Regions, respectively, to provide a basic CORS network in accordance with the International Terrestrial Reference Frame (ITRF). However, most surveyors continue to reference their works in these regions to ground survey beacons that have been coordinated and adjusted by variable survey methods. This obviously makes homogeneity of data unpredictable. This study explored the extent of usage of existing CORS network established by SMD with particular focus on the CORS in the Greater Accra Region for GPS surveys and to determine its usefulness in ensuring homogeneity in GPS data collection. The professional participatory (interviews) technique was coupled with differential GPS field observations with the CORS as reference in one case and ground control stations as reference in the other in making relatively conclusive analysis. Test results showed that GPS field survey of an approximate range of 23 km away from the Accra CORS yielded an average positional change in Northings and Eastings of − 0.790 m, − 0.176 m and − 0.681 m, − 0.098 m for single and dual frequency, respectively, in different localities within the study area. Beyond a range of 25 km from the Accra CORS, the average positional change in Northings and Eastings are − 0.536 m, − 0.007 m and − 1.370 m, 0.334 m for single and dual frequency respectively. Of 128 geomatic professionals interviewed, 39% are aware of the availability of COR stations in Greater Accra, 61% are unaware, and 28% are aware and users of the Accra CORS whereas 11% are aware but non-users of the Accra COR station. Of all users sampled, 17.5% are regular and frequent users of the Accra COR station and 10.5% are occasional or seldom users. The results show that the Accra CORS is vital to ensuring a uniform homogenous GPS data. However, very few people are using it due to low public awareness of the usefulness of the CORS among professional surveyors and other users and a cumbersome, bureaucratic nature in CORS data acquisition for post-processing and RTK GPS surveys. Numéro de notice : A2020-723 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s41651-020-00061-8 date de publication en ligne : 11/09/2020 En ligne : https://doi.org/10.1007/s41651-020-00061-8 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96324 [article]

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)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 86 n° 7 (July 2020) . - pp 397-403 Titre : Rethinking error estimations in geospatial data: the correct way to determine product accuracy Type de document : Article/Communication Auteurs : Qassim Abdullah, Auteur Année de publication : 2020 Article en page(s) : pp 397-403 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Topographie moderne [Termes descripteurs IGN] cartographie numérique [Termes descripteurs IGN] détection d'erreur [Termes descripteurs IGN] données localisées [Termes descripteurs IGN] ellipsoïde (géodésie) [Termes descripteurs IGN] estimation de précision [Termes descripteurs IGN] nivellement direct [Termes descripteurs IGN] point d'appui [Termes descripteurs IGN] réalité de terrain [Termes descripteurs IGN] système de référence géodésique [Termes descripteurs IGN] système de référence local Résumé : (Auteur) Numéro de notice : A2020-380 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.14358/PERS.86.7.397 date de publication en ligne : 01/07/2020 En ligne : https://doi.org/10.14358/PERS.86.7.397 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95425 [article]

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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)  

Public [article]  inSurvey review > vol 52 n° 373 (July 2020) . - pp 317 - 329 Titre : Triangulation network of 1929–1944 of the first 1:500 urban map of València Type de document : Article/Communication Auteurs : Miriam Villar-Cano, Auteur ; Ángel Marqués‐Mateu, Auteur ; María Jesús Jiménez-Martínez, Auteur Année de publication : 2020 Article en page(s) : pp 317 - 329 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Triangulation [Termes descripteurs IGN] 1:500 [Termes descripteurs IGN] arpentage [Termes descripteurs IGN] carte ancienne [Termes descripteurs IGN] cartographie urbaine [Termes descripteurs IGN] données de terrain [Termes descripteurs IGN] European Terrestrial Reference System 1989 [Termes descripteurs IGN] réseau de triangulation [Termes descripteurs IGN] transformation de coordonnées [Termes descripteurs IGN] Valence (Espagne) Résumé : (auteur) Triangulation is a surveying method on which earlier maps made were based. Although the origins of the method can be traced back to the 16th century, it is still used today, with minor changes, to adjust networks observed with modern geodetic techniques. In this paper we present the geodetic survey work that was carried out for the primary triangulation network of the first 1:500 urban map of the city of València (Spain). It spanned from 1929 to 1944 and resulted in 421 maps covering about 174 square kilometres. We focus on four key elements to define the geometric framework of a map: (1) the geodetic network, (2) the cartographic projection, (3) the baseline measurements, and (4) the primary triangulation. The paper is based on the interpretation of original documents and field books recovered from the archives of the València City Council. In order to check the accuracy and consistency of the survey work, we recomputed all calculations directly from the field data, following the mathematical procedures of the time. We obtained a set of transformation parameters to convert the coordinates of 1929 to current coordinates based on the European Terrestrial Reference System of 1989 (ETRS89). Results showed that the 1929 primary triangulation angles and coordinates are accurate to 8 s of arc and 35 cm respectively, and that the coordinates transform well into the current reference system with average residuals of 26 cm across nine control points, demonstrating the high quality of the 1929 work. Numéro de notice : A2020-395 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2018.1564599 date de publication en ligne : 03/01/2019 En ligne : https://doi.org/10.1080/00396265.2018.1564599 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95421 [article]

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)  

Public [article]  inJournal of geodesy > vol 93 n°11 (November 2019) Titre : Impact of network constraining on the terrestrial reference frame realization based on SLR observations to LAGEOS Type de document : Article/Communication Auteurs : Radoslaw Zajdel, Auteur ; Krzysztof Sosnica, Auteur ; M. Drożdżewski, Auteur ; Grzegorz Bury, Auteur ; D. Strugarek, Auteur Année de publication : 2019 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes descripteurs IGN] géocentre [Termes descripteurs IGN] International Terrestrial Reference Frame [Termes descripteurs IGN] Lageos [Termes descripteurs IGN] réseau de contraintes [Termes descripteurs IGN] rotation de la Terre [Termes descripteurs IGN] station TLS (télémétrie) [Termes descripteurs IGN] système de référence géodésique [Termes descripteurs IGN] système de référence local [Termes descripteurs IGN] télémétrie laser sur satellite [Termes descripteurs IGN] transformation de Helmert Résumé : (auteur) The Satellite Laser Ranging (SLR) network struggles with some major limitations including an inhomogeneous global station distribution and uneven performance of SLR sites. The International Laser Ranging Service (ILRS) prepares the time-variable list of the most well-performing stations denoted as ‘core sites’ and recommends using them for the terrestrial reference frame (TRF) datum realization in SLR processing. Here, we check how different approaches of the TRF datum realization using minimum constraint conditions (MCs) and the selection of datum-defining stations affect the estimated SLR station coordinates, the terrestrial scale, Earth rotation parameters (ERPs), and geocenter coordinates (GCC). The analyses are based on the processing of the SLR observations to LAGEOS-1/-2 collected between 2010 and 2018. We show that it is essential to reject outlying stations from the reference frame realization to maintain a high quality of SLR-based products. We test station selection criteria based on the Helmert transformation of the network w.r.t. the a priori SLRF2014 coordinates to reject misbehaving stations from the list of datum-defining stations. The 25 mm threshold is optimal to eliminate the epoch-wise temporal deviations and to provide a proper number of datum-defining stations. According to the station selection algorithm, we found that some of the stations that are not included in the list of ILRS core sites could be taken into account as potential core stations in the TRF datum realization. When using a robust station selection for the datum definition, we can improve the station coordinate repeatability by 8%, 4%, and 6%, for the North, East and Up components, respectively. The global distribution of datum-defining stations is also crucial for the estimation of ERPs and GCC. When excluding just two core stations from the SLR network, the amplitude of the annual signal in the GCC estimates is changed by up to 2.2 mm, and the noise of the estimated pole coordinates is substantially increased. Numéro de notice : A2019-610 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-019-01307-0 date de publication en ligne : 17/10/2019 En ligne : https://doi.org/10.1007/s00190-019-01307-0 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94794 [article]

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

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Assessing a new velocity field in Greece towards a new semi-kinematic datum / S. Bitharis in Survey review, vol 51 n° 368 (September 2019)  

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Quand la légistique rattrape le train de la géodésie ... / Gilles Canaud in XYZ, n° 159 (juin 2019)

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Extension de fuseau de la projection de Mercator Transverse : Application au réseau géodésique primordial Algérien / Bachir Gourine in XYZ, n° 155 (juin - août 2018)

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Le CNIG et les références géodésiques / Françoise Duquenne in XYZ, n° 154 (mars - mai 2018)

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Les systèmes de référence terrestre et leurs réalisations : cas des territoires français / Françoise Duquenne in XYZ, n° 154 (mars - mai 2018)

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Introduction to multiple regression equations in datum transformations and their reversibility / A.C. Ruffhead in Survey review, vol 50 n° 358 (January 2018)  

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Application of the undifferenced GNSS precise positioning in determining coordinates in national reference frames / Grzegorz Krzan in Artificial satellites, vol 52 n° 3 (September 2017)  

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Estimating benefits to Canada and the world : the canadian spatial reference system precise point positioning service / Calvin Klatt in Geomatica [en ligne], vol 71 n° 1 (March 2017)  

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Transformation of distorted geodetic networks to new coordinate reference systems : a case study for ED50-ITRFXX transformation in Turkey / Metin Soycan in Geodetski vestnik, vol 61 n° 1 (March - May 2017)  

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