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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 descripteurs IGN] azimut gyroscopique [Termes descripteurs IGN] compensation de coordonnées [Termes descripteurs IGN] lever souterrain [Termes descripteurs IGN] réseau géodésique spécifique [Termes descripteurs 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 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 descripteurs IGN] compensation de coordonnées [Termes descripteurs IGN] compensation par moindres carrés [Termes descripteurs IGN] désert [Termes descripteurs IGN] Egypte [Termes descripteurs IGN] fouille archéologique [Termes descripteurs IGN] réseau géodésique local [Termes descripteurs IGN] réseau géodésique spécifique [Termes descripteurs 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 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 descripteurs IGN] compensation de coordonnées [Termes descripteurs IGN] fiabilité des données [Termes descripteurs IGN] génie civil [Termes descripteurs IGN] réseau géodésique spécifique [Termes descripteurs 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 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 : [Vedettes matières IGN] Nivellement [Termes descripteurs IGN] altitude orthométrique [Termes descripteurs IGN] coefficient de corrélation [Termes descripteurs IGN] compensation de coordonnées [Termes descripteurs IGN] erreur en position [Termes descripteurs IGN] géoïde gravimétrique [Termes descripteurs IGN] hauteur ellipsoïdale [Termes descripteurs IGN] North American Vertical Datum 1988 [Termes descripteurs IGN] Oregon (Etats-Unis) [Termes descripteurs IGN] système de référence altimétrique 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 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)  

Public [article]  inJournal of applied geodesy > vol 11 n° 2 (June 2017) . - pp 67 - 76 Titre : Uncertainty assessment in geodetic network adjustment by combining GUM and Monte-Carlo-simulations Type de document : Article/Communication Auteurs : Wolfgang Niemeier, Auteur ; Dieter Tengen, Auteur Année de publication : 2017 Article en page(s) : pp 67 - 76 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes descripteurs IGN] compensation de coordonnées [Termes descripteurs IGN] données GNSS [Termes descripteurs IGN] incertitude géométrique [Termes descripteurs IGN] intervalle de confiance [Termes descripteurs IGN] matrice de covariance [Termes descripteurs IGN] méthode de Monte-Carlo [Termes descripteurs IGN] Metsähovi [Termes descripteurs IGN] point de liaison (géodésie) [Termes descripteurs IGN] réseau géodésique Résumé : (Auteur) In this article, first ideas are presented to extend the classical concept of geodetic network adjustment by introducing a new method for uncertainty assessment as two-step analysis. In the first step the raw data and possible influencing factors are analyzed using uncertainty modeling according to GUM (Guidelines to the Expression of Uncertainty in Measurements). This approach is well established in metrology, but rarely adapted within Geodesy. The second step consists of Monte-Carlo-Simulations (MC-simulations) for the complete processing chain from raw input data and pre-processing to adjustment computations and quality assessment. To perform these simulations, possible realizations of raw data and the influencing factors are generated, using probability distributions for all variables and the established concept of pseudo-random number generators. Final result is a point cloud which represents the uncertainty of the estimated coordinates; a confidence region can be assigned to these point clouds, as well. This concept may replace the common concept of variance propagation and the quality assessment of adjustment parameters by using their covariance matrix. It allows a new way for uncertainty assessment in accordance with the GUM concept for uncertainty modelling and propagation. As practical example the local tie network in “Metsähovi Fundamental Station”, Finland is used, where classical geodetic observations are combined with GNSS data. Numéro de notice : A2017-283 Thématique : POSITIONNEMENT Nature : Article En ligne : https://doi.org/10.1515/jag-2016-0017 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85316 [article]

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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Quelques procédures pouvant améliorer la qualité d'un réseau gravimétrique / A. Bourmatte in Bulletin des sciences géographiques, n° 28 (juin 2013)

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