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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 IGN] compensation de coordonnées [Termes IGN] données GNSS [Termes IGN] incertitude géométrique [Termes IGN] intervalle de confiance [Termes IGN] matrice de covariance [Termes IGN] méthode de Monte-Carlo [Termes IGN] Metsähovi [Termes IGN] point de liaison (géodésie) [Termes 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 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/jag-2016-0017 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]

Deformation monitoring of the submillimetric UPV calibration baseline / Luis García-Asenjo in Journal of applied geodesy, vol 11 n° 2 (June 2017)  

Public [article]  inJournal of applied geodesy > vol 11 n° 2 (June 2017) . - pp 107 - 114 Titre : Deformation monitoring of the submillimetric UPV calibration baseline Type de document : Article/Communication Auteurs : Luis García-Asenjo, Auteur ; Sergio Baselga, Auteur ; Pascual Garrigues, Auteur Année de publication : 2017 Article en page(s) : pp 107 - 114 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] base géodésique [Termes IGN] déformation géométrique [Termes IGN] distancemètre [Termes IGN] étalonnage d'instrument [Termes IGN] mécomètre [Termes IGN] stabilité [Termes IGN] Valence (Espagne) Résumé : (Auteur) A 330 m calibration baseline was established at the Universitat Politècnica de València (UPV) in 2007. Absolute scale was subsequently transferred in 2012 from the Nummela Standard Baseline in Finland and distances between pillars were determined with uncertainties ranging from 0.1 mm to 0.3 mm. In order to assess the long-term stability of the baseline, three field campaigns were carried out from 2013 to 2015 in a co-operative effort with the Universidad Complutense de Madrid (UCM), which provided the only Mekometer ME5000 distance meter available in Spain. Since the application of the ISO17123-4 full procedure did not suffice to come to a definite conclusion about possible displacements of the pillars, we opted for the traditional geodetic network approach. This approach had to be adapted to the case at hand in order to deal with problems such as the geometric weakness inherent to calibration baselines and scale uncertainty derived from both the use of different instruments and the high correlation between the meteorological correction and scale determination. Additionally, the so-called the maximum number of stable points method was also tested. In this contribution, it is described the process followed to assess the stability of the UPV submillimetric calibration baseline during the period of time from 2012 to 2015. Numéro de notice : A2017-284 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/jag-2016-0018 En ligne : https://doi.org/10.1515/jag-2016-0018 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85317 [article]