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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)  

Public [article]  inJournal of geodetic science > vol 11 n° 1 (January 2021) . - pp 38 - 47 Titre : Positional uncertainty of network RTK observations in a modern datum Type de document : Article/Communication Auteurs : T. Bernstein, Auteur ; Volker Janssen, Auteur Année de publication : 2021 Article en page(s) : pp 38 - 47 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] compensation de coordonnées [Termes IGN] Geocentric Datum of Australia 2020 [Termes IGN] incertitude de position [Termes IGN] Nouvelle-Galles du Sud [Termes IGN] positionnement cinématique en temps réel [Termes IGN] station virtuelle de référence Résumé : (auteur) The Geocentric Datum of Australia 2020 (GDA2020) is Australia’s new and much improved national datum. It is based on a single, nationwide leastsquares network adjustment that rigorously propagates uncertainty. This paper explores three options to include Network Real-Time Kinematic (NRTK) observations and their Positional Uncertainty (PU) in the survey control network of New South Wales (NSW) via the GDA2020 state adjustment. In the first option, PU is empirically estimated based on a dataset of more than 1,500 observations to obtain values that can be uniformly applied to all NRTK observations. In the second option, PU is calculated for each NRTK observation, based on the coordinate quality indicators provided by the Global Navigation Satellite System (GNSS) equipment. Both options continue to treatNRTK observations as point-based position solutions, resulting in poor correlation with surrounding surveycontrol marks. The third option overcomes this issue by utilising the automatically computed GNSS baselines between NRTK observations and their Virtual Reference Station (VRS) to create a connected network that can be adjusted like a static GNSS network. Using a typical urban NRTK survey in Sydney as an example, it is shown that this method offers a rigorous computation of PU, while maintaining the quick and easy nature of NRTK positioning. Numéro de notice : A2021-980 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/jogs-2020-0116 Date de publication en ligne : 10/08/2021 En ligne : https://doi.org/10.1515/jogs-2020-0116 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100977 [article]

Adjustment options for a survey network with magnetic levitation gyro data in an immersed under-sea tunnel / Ji Ma in Survey review, vol 51 n° 367 (July 2019)  

Public [article]  inSurvey review > vol 51 n° 367 (July 2019) . - pp 373 - 386 Titre : Adjustment options for a survey network with magnetic levitation gyro data in an immersed under-sea tunnel Type de document : Article/Communication Auteurs : Ji Ma, Auteur ; Zhiqiang Yang, Auteur ; Zhen Shi, Auteur ; et al., Auteur Année de publication : 2019 Article en page(s) : pp 373 - 386 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Topographie [Termes IGN] compensation de coordonnées [Termes IGN] gyroscope [Termes IGN] lever souterrain [Termes IGN] réseau géodésique spécifique [Termes IGN] tunnel Résumé : (Auteur) Since gyro azimuths are affected by the complex environmental factors that are present in underground spaces, the adjustment model should take this into account. In general, gyro azimuths are considered to be errorless or equal precision observations in the adjustment model, which leads to the overestimation or underestimation of the weight of the gyro azimuths. To improve the precision of underground networks, measured with a magnetic levitation gyroscope, an adjustment for the survey network with individually weighted gyro observations is proposed. The proposed method was tested on an equivalent mock-up network of the tunnels associated with the Hong Kong-Zhuhai-Macau Bridge. The lateral breakthrough error and lateral standard deviation at the breakthrough point were calculated and compared. Our result shows that the lateral breakthrough error was 4.8 mm with the precision change ratio of 64.5% which suggested that the proposed method is able to improve the precision of the breakthrough point. Numéro de notice : A2019-365 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2018.1563376 Date de publication en ligne : 03/01/2019 En ligne : https://doi.org/10.1080/00396265.2018.1563376 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93454 [article]

Spatial information recovery in the desert using LMS-based geodetic network adjustment / Eva Stopková in Survey review, vol 51 n° 367 (July 2019)  

Public [article]  inSurvey review > vol 51 n° 367 (July 2019) . - pp 334 - 344 Titre : Spatial information recovery in the desert using LMS-based geodetic network adjustment Type de document : Article/Communication Auteurs : Eva Stopková, Auteur Année de publication : 2019 Article en page(s) : pp 334 - 344 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Topographie [Termes IGN] compensation de coordonnées [Termes IGN] compensation par moindres carrés [Termes IGN] désert [Termes IGN] Egypte [Termes IGN] fouille archéologique [Termes IGN] réseau géodésique local [Termes IGN] réseau géodésique spécifique [Termes IGN] site archéologique Résumé : (Auteur) This paper describes the local coordinate system recovery at the archaeological site Tell el-Retaba (Egypt), without any GNSS technology or the positioning in an official reference frame available. Completely destroyed control points were restored using geodetic network adjustment based on terrestrial observations and multi-epoch solution of the Least Mean Square models, and transformed into the original local coordinate system using identical points located on ancient mud-brick structures in former trenches. However, current and past measurements of excavated objects fit almost perfectly. Statistical and empirical tests indicate that the outliers correspond with measurements in harsh desert conditions. Numéro de notice : A2019-362 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2018.1459360 Date de publication en ligne : 23/04/2018 En ligne : https://doi.org/10.1080/00396265.2018.1459360 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93439 [article]

Reliability analysis for non-distorting connection of engineering survey networks / Witold Proszynski in Survey review, vol 51 n° 366 (May 2019)  

Public [article]  inSurvey review > vol 51 n° 366 (May 2019) . - pp 219 - 224 Titre : Reliability analysis for non-distorting connection of engineering survey networks Type de document : Article/Communication Auteurs : Witold Proszynski, Auteur ; Slawomir Łapiński, Auteur Année de publication : 2019 Article en page(s) : pp 219 - 224 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] compensation de coordonnées [Termes IGN] fiabilité des données [Termes IGN] génie civil [Termes IGN] réseau géodésique spécifique [Termes IGN] transformation de Helmert Résumé : (Auteur) A non-distorting network connection is a complex procedure consisting of a local network adjustment and a subsequent Helmert transformation into the connection points without changing the scale, i.e. isometry transformation. Since a joint adjustment model proposed for this connection in the earlier publication did not turn out sufficient to create a detailed reliability description for the whole procedure, reference had to be made to the original two-step approach. The reliability measures for a joint model and for each of the above mentioned procedural steps of the connection are being analysed. It is shown that the reliability description as based on indices obtained from the joint model should be supplemented with the indices from the two-step model. A specific property of the connection concerning mutual controllability of coordinates of the connection points is formulated on the basis of the Helmert transformation. The theory is illustrated on some numerical examples. Numéro de notice : A2019-193 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2018.1425605 Date de publication en ligne : 24/01/2018 En ligne : https://doi.org/10.1080/00396265.2018.1425605 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92639 [article]

On determining orthometric heights from a corrector surface model based on leveling observations, GNSS, and a geoid model / Su-Kyung Kim in Journal of applied geodesy, vol 12 n° 4 (October 2018)  

Public [article]  inJournal of applied geodesy > vol 12 n° 4 (October 2018) . - pp 323 - 333 Titre : On determining orthometric heights from a corrector surface model based on leveling observations, GNSS, and a geoid model Type de document : Article/Communication Auteurs : Su-Kyung Kim, Auteur ; Jihye Park, Auteur ; Daniel T. Gillins, Auteur ; Michael Dennis, Auteur Année de publication : 2018 Article en page(s) : pp 323 - 333 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] altitude orthométrique [Termes IGN] coefficient de corrélation [Termes IGN] compensation de coordonnées [Termes IGN] erreur en position [Termes IGN] géoïde gravimétrique [Termes IGN] hauteur ellipsoïdale [Termes IGN] North American Vertical Datum 1988 [Termes IGN] Oregon (Etats-Unis) [Termes IGN] système de référence altimétrique [Vedettes matières IGN] Altimétrie Résumé : (auteur) Leveling is a traditional geodetic surveying technique that has been used to realize a vertical datum. However, this technique is time consuming and prone to accumulate errors, where it relies on starting from one station with a known orthometric height. Establishing orthometric heights using Global Navigation Satellite Systems (GNSS) and a geoid model has been suggested [14], but this approach may involve less precisions than the direct measurements from leveling. In this study, an experimental study is presented to adjust the highly accurate leveling observations along with orthometric heights derived from GNSS observations and a geoid model. For the geoid model, the National Geodetic Survey’s gravimetric geoid model (TxGEOID16B) and hybrid geoid model (GEOID12B) were applied. Uncertainties in the leveled height differences, GNSS derived heights, and the geoid models were modeled, and a combined adjustment was implemented to construct the optimal combination of orthometric, ellipsoidal, and geoid height at each mark. As a result, the discrepancy from the published orthometric heights and the CSM (Corrector Surface Model) based adjusted orthometric heights with GEOID12B showed a mean and RMS of -8.5 mm and 16.6 mm, respectively, while TxGEOID16B had a mean and RMS of 28.9 mm and 34.6 mm, respectively. It should be emphasized that this approach was not influenced by the geodetic distribution of the stations where the correlation coefficients between the distance from the center of the surveying network and the discrepancy from the published heights using TxGEOID16B and GEOID12B are 0.03 and 0.36, respectively. Numéro de notice : A2018-672 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jag-2018-0014 Date de publication en ligne : 29/08/2018 En ligne : https://doi.org/10.1515/jag-2018-0014 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91004 [article]

Uncertainty assessment in geodetic network adjustment by combining GUM and Monte-Carlo-simulations / Wolfgang Niemeier in Journal of applied geodesy, vol 11 n° 2 (June 2017)  

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A concept for the examination of reference points stability in horizontal control networks / Ryszard Malarski in Reports on geodesy and geoinformatics, vol 101 (June 2016)  

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Empirical methods of reducing the observations in geodetic networks / Roman Kadaj in Geodesy and cartography, vol 65 n° 1 (June 2016)  

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A correctly weighted least squares adjustment - Part 3 Estimating standard errors in angular observations / Charles D. Ghilani in xyHt, vol 2016 n° 4 (April 2016)

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Time series analysis of 3D coordinates using nonstochastic observations / Hiddo Velsink in Journal of applied geodesy, vol 10 n° 1 (March 2016)  

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A correctly weighted least squares adjustment - Part 2 Estimating uncertainties / Charles D. Ghilani in xyHt, vol 2016 n° 2 (February 2016)

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A correctly weighted least squares adjustment - Part 1 Problems from using computed standard deviations / Charles D. Ghilani in xyHt, vol 2016 n° 1 (January 2016)

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Managua ITRF local tie (Nicaragua) / Jean-Claude Poyard (2016) 

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Métrologie par photogrammétrie aéroportée légère : application au suivi d'évolution de digues / Vincent Tournadre (2015)  

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Interface de GNU GAMA / Maxime Le Moual (2014) 

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