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The European GeoMetre project: developing enhanced large-scale dimensional metrology for geodesy / Florian Pollinger in Applied geomatics, vol 15 n° inconnu (2023)  

Public [article]  inApplied geomatics > vol 15 n° inconnu (2023) Titre : The European GeoMetre project: developing enhanced large-scale dimensional metrology for geodesy Type de document : Article/Communication Auteurs : Florian Pollinger, Auteur ; Sergio Baselga, Auteur ; Clément Courde, Auteur ; Cornelia Eschelbach, Auteur ; Luis García-Asenjo, Auteur ; Pascual Garrigues, Auteur ; Joffray Guillory, Auteur ; Per Olof Hedekvist, Auteur ; Tuomas Helojärvi, Auteur ; Jorma Jokela, Auteur ; Ulla Kallio, Auteur ; Thomas Klügel, Auteur ; Paul Köchert, Auteur ; Michael Lösler, Auteur ; Raquel Luján, Auteur ; Tobias Meyer, Auteur ; Pavel Neyezhmakov, Auteur ; Damien Pesce, Auteur ; et al., Auteur Année de publication : 2023 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie [Termes IGN] grande échelle [Termes IGN] métrologie tridimensionnelle Résumé : (auteur) We provide a survey on the joint European research project “GeoMetre”, which explores novel technologies and their inclusion to existing surveying strategies to improve the traceability of geodetic reference frames to the SI definition of the metre. This work includes the development of novel distance meters with a range of up to 5 km, the realisation of optical multilateration systems for large structure monitoring at an operation distance of 50 m and beyond, and a novel strategy for GNSS-based distance determination. Different methods for refractivity compensation, based on classical sensors, on dispersion, on spectroscopic thermometry, and on the speed of sound to reduce the meteorological uncertainties in precise distance measurements, are developed further and characterised. These systems are validated at and applied to the novel European standard baseline EURO5000 at the Pieniny Kippen Belt, Poland, which was completely refurbished and intensely studied in this project. We use our novel instruments for a reduced uncertainty of the scale in the surveillance networks solutions for local tie measurements at space-geodetic co-location stations. We also investigate novel approaches like close-range photogrammetry to reference point determination of space-geodetic telescopes. Finally, we also investigate the inclusion of the local gravity field to consider the deviations of the vertical in the data analysis and to reduce the uncertainty of coordinate transformations in this complex problem. Numéro de notice : A2023-089 Affiliation des auteurs : IGN+Ext (2020- ) Autre URL associée : vers HAL Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s12518-022-00487-3 Date de publication en ligne : 20/02/2023 En ligne : https://doi.org/10.1007/s12518-022-00487-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=103089 [article]

Voir aussi

• Large-scale dimensional metrology for geodesy: First results from the European GeoMetre project / Florian Pollinger (2022)  

Bias in least-squares adjustment of implicit functional models / Michael Lösler in Survey review, Vol 53 n° 378 (May 2021)  

Public [article]  inSurvey review > Vol 53 n° 378 (May 2021) . - pp 223 - 234 Titre : Bias in least-squares adjustment of implicit functional models Type de document : Article/Communication Auteurs : Michael Lösler, Auteur ; Rüdiger Lehmann, Auteur ; Frank Neitzel, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : pp 223 - 234 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] compensation par moindres carrés [Termes IGN] erreur systématique [Termes IGN] fonction de Bessel [Termes IGN] méthode de Monte-Carlo [Termes IGN] modèle non linéaire [Termes IGN] modèle stochastique [Termes IGN] série de Taylor [Termes IGN] substitution [Termes IGN] transformation de coordonnées Résumé : (auteur) To evaluate the benefit of a measurement procedure onto the estimated parameters, the dispersion of the parameters is usually used. To draw objective conclusions, unbiased or at least almost unbiased estimates are required. In geodesy, most of the functional relations are nonlinear but the statistical properties of the estimates are usually obtained by a linearised substitute-problem. Since the statistical properties of linear models cannot be passed to the nonlinear case, the estimates are biased. In this contribution, the bias of the parameters as well as the bias of the dispersion in nonlinear implicit models is investigated, using a second-order Taylor expansion. Nonlinear implicit models are general models and are used, for instance, in the framework of surface-fitting or coordinate transformation, which considers errors for the coordinates in source and target system. The bias is introduced as a further indicator to validate the benefit of an adapted measurement process using more precise measuring instruments. Since some parametrisations yield an ill-posed problem, also the case of a singular equation system is investigated. To demonstrate the second-order effect onto the estimates, a best-fitting plane is adjusted under varying configurations. Such a configuration is recommended in evaluating uncertainties of optical 3D measuring systems, e.g. in the framework of the VDI/VDE 2634 guideline. The estimated bias is used as an indicator whether a large number of poor observations provides better results than a small but precise sample. Numéro de notice : A2021-404 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2020.1715680 Date de publication en ligne : 29/01/2020 En ligne : https://doi.org/10.1080/00396265.2020.1715680 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97717 [article]

Congruence analysis of geodetic networks, hypothesis tests versus model selection by information criteria / Rüdiger Lehmann in Journal of applied geodesy, vol 11 n° 4 (December 2017)  

Public [article]  inJournal of applied geodesy > vol 11 n° 4 (December 2017) . - pp 271 - 283 Titre : Congruence analysis of geodetic networks, hypothesis tests versus model selection by information criteria Type de document : Article/Communication Auteurs : Rüdiger Lehmann, Auteur ; Michael Lösler, Auteur Année de publication : 2017 Article en page(s) : pp 271 - 283 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] analyse de données [Termes IGN] congruence [Termes IGN] déformation géométrique [Termes IGN] réseau géodésique Résumé : (Auteur) Geodetic deformation analysis can be interpreted as a model selection problem. The null model indicates that no deformation has occurred. It is opposed to a number of alternative models, which stipulate different deformation patterns. A common way to select the right model is the usage of a statistical hypothesis test. However, since we have to test a series of deformation patterns, this must be a multiple test. As an alternative solution for the test problem, we propose the p-value approach. Another approach arises from information theory. Here, the Akaike information criterion (AIC) or some alternative is used to select an appropriate model for a given set of observations. Both approaches are discussed and applied to two test scenarios: A synthetic levelling network and the Delft test data set. It is demonstrated that they work but behave differently, sometimes even producing different results. Hypothesis tests are well-established in geodesy, but may suffer from an unfavourable choice of the decision error rates. The multiple test also suffers from statistical dependencies between the test statistics, which are neglected. Both problems are overcome by applying information criterions like AIC. Numéro de notice : A2017-792 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/jag-2016-0049 En ligne : https://doi.org/10.1515/jag-2016-0049 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89064 [article]

Automated and continual determination of radio telescope reference points with sub-mm accuracy: results from a campaign at the Onsala Space Observatory / Michael Lösler in Journal of geodesy, vol 87 n° 8 (August 2013)  

Public [article]  inJournal of geodesy > vol 87 n° 8 (August 2013) . - pp 791 - 804 Titre : Automated and continual determination of radio telescope reference points with sub-mm accuracy: results from a campaign at the Onsala Space Observatory Type de document : Article/Communication Auteurs : Michael Lösler, Auteur ; Rüdiger Haas, Auteur ; Cornelia Eschelbach, Auteur Année de publication : 2013 Article en page(s) : pp 791 - 804 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] Global Geodetic Observing System [Termes IGN] interférométrie à très grande base [Termes IGN] point d'appui [Termes IGN] précision submillimétrique [Termes IGN] radiotélescope Résumé : (Auteur) The Global Geodetic Observing System (GGOS) requires sub-mm accuracy, automated and continual determinations of the so-called local tie vectors at co-location stations. Co-location stations host instrumentation for several space geodetic techniques and the local tie surveys involve the relative geometry of the reference points of these instruments. Thus, these reference points need to be determined in a common coordinate system, which is a particular challenge for rotating equipment like radio telescopes for geodetic Very Long Baseline Interferometry. In this work we describe a concept to achieve automated and continual determinations of radio telescope reference points with sub-mm accuracy. We developed a monitoring system, including Java-based sensor communication for automated surveys, network adjustment and further data analysis. This monitoring system was tested during a monitoring campaign performed at the Onsala Space Observatory in the summer of 2012. The results obtained in this campaign show that it is possible to perform automated determination of a radio telescope reference point during normal operations of the telescope. Accuracies on the sub-mm level can be achieved, and continual determinations can be realized by repeated determinations and recursive estimation methods Numéro de notice : A2013-483 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-013-0647-y Date de publication en ligne : 12/06/2013 En ligne : https://doi.org/10.1007/s00190-013-0647-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32621 [article]

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