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Reduction of ZTD outliers through improved GNSS data processing and screening strategies [Interactive discussion] / Katarzyna Stępniak in Atmospheric measurement techniques, vol 11 n° 3 (March 2018)
[article]
Titre : Reduction of ZTD outliers through improved GNSS data processing and screening strategies [Interactive discussion] Type de document : Article/Communication Auteurs : Katarzyna Stępniak, Auteur ; Olivier Bock , Auteur ; Pawel Wielgosz, Auteur Année de publication : 2018 Projets : 3-projet - voir note / Article en page(s) : pp 1347 - 1361 Note générale : Bibliographie
This work has been supported by Polish National Science Centre grant no. UMO-2015/19/B/ST10/02758. The study was partially carried out during Short Term Scientific Mission (STSM) in the framework of ES1206 COST Action.Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] Bernese
[Termes IGN] coordonnées GPS
[Termes IGN] double différence
[Termes IGN] erreur systématique
[Termes IGN] Pologne
[Termes IGN] réseau géodésique local
[Termes IGN] réseau géodésique permanent
[Termes IGN] retard troposphérique zénithal
[Termes IGN] série temporelle
[Termes IGN] valeur aberranteRésumé : (Auteur) Though Global Navigation Satellite System (GNSS) data processing has been significantly improved over the years, it is still commonly observed that zenith tropospheric delay (ZTD) estimates contain many outliers which are detrimental to meteorological and climatological applications. In this paper, we show that ZTD outliers in double-difference processing are mostly caused by sub-daily data gaps at reference stations, which cause disconnections of clusters of stations from the reference network and common mode biases due to the strong correlation between stations in short baselines. They can reach a few centimetres in ZTD and usually coincide with a jump in formal errors. The magnitude and sign of these biases are impossible to predict because they depend on different errors in the observations and on the geometry of the baselines. We elaborate and test a new baseline strategy which solves this problem and significantly reduces the number of outliers compared to the standard strategy commonly used for positioning (e.g. determination of national reference frame) in which the pre-defined network is composed of a skeleton of reference stations to which secondary stations are connected in a star-like structure. The new strategy is also shown to perform better than the widely used strategy maximizing the number of observations available in many GNSS programs. The reason is that observations are maximized before processing, whereas the final number of used observations can be dramatically lower because of data rejection (screening) during the processing. The study relies on the analysis of 1 year of GPS (Global Positioning System) data from a regional network of 136 GNSS stations processed using Bernese GNSS Software v.5.2. A post-processing screening procedure is also proposed to detect and remove a few outliers which may still remain due to short data gaps. It is based on a combination of range checks and outlier checks of ZTD and formal errors. The accuracy of the final screened GPS ZTD estimates is assessed by comparison to ERA-Interim reanalysis. Numéro de notice : A2018-065 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.5194/amt-11-1347-2018 Date de publication en ligne : 08/03/2018 En ligne : http://dx.doi.org/10.5194/amt-11-1347-2018 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89407
in Atmospheric measurement techniques > vol 11 n° 3 (March 2018) . - pp 1347 - 1361[article]High performance clocks and gravity field determination / Jurgen Müller in Space Science Reviews, vol 214 n° 1 (February 2018)
[article]
Titre : High performance clocks and gravity field determination Type de document : Article/Communication Auteurs : Jurgen Müller, Auteur ; D. Dirkx, Auteur ; S. M. Kopeikin, Auteur ; Guillaume Lion , Auteur ; Isabelle Panet , Auteur ; Gérard Petit, Auteur ; Pieter N.A.M. Visser, Auteur Année de publication : 2018 Projets : 3-projet - voir note / , AdOC / Note générale : bibliographie
Jürgen Müller gratefully acknowledges support by the DFG Sonderforschungsbereich (SFB 1128: geo-Q) Relativistic Geodesy and Gravimetry with Quantum Sensors.Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] chronométrie
[Termes IGN] échelle de temps
[Termes IGN] gravimétrie spatiale
[Termes IGN] horloge atomique
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] potentiel de pesanteur terrestre
[Termes IGN] relativité généraleRésumé : (auteur) Time measured by an ideal clock crucially depends on the gravitational potential and velocity of the clock according to general relativity. Technological advances in manufacturing high-precision atomic clocks have rapidly improved their accuracy and stability over the last decade that approached the level of 10−18. This notable achievement along with the direct sensitivity of clocks to the strength of the gravitational field make them practically important for various geodetic applications that are addressed in the present paper. Based on a fully relativistic description of the background gravitational physics, we discuss the impact of those highly-precise clocks on the realization of reference frames and time scales used in geodesy. We discuss the current definitions of basic geodetic concepts and come to the conclusion that the advances in clocks and other metrological technologies will soon require the re-definition of time scales or, at least, clarification to ensure their continuity and consistent use in practice. The relative frequency shift between two clocks is directly related to the difference in the values of the gravity potential at the points of clock’s localization. According to general relativity the relative accuracy of clocks in 10−18 is equivalent to measuring the gravitational red shift effect between two clocks with the height difference amounting to 1 cm. This makes the clocks an indispensable tool in high-precision geodesy in addition to laser ranging and space geodetic techniques. We show how clock measurements can provide geopotential numbers for the realization of gravity-field-related height systems and can resolve discrepancies in classically-determined height systems as well as between national height systems. Another application of clocks is the direct use of observed potential differences for the improved recovery of regional gravity field solutions. Finally, clock measurements for space-borne gravimetry are analyzed along with closely-related deficiencies of this method like an extra-ordinary knowledge of the spacecraft velocity, etc. For all these applications besides the near-future prospects, we also discuss the challenges that are related to using those novel clock data in geodesy. Numéro de notice : A2018-197 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s11214-017-0431-z Date de publication en ligne : 30/11/2017 En ligne : https://doi.org/10.1007/s11214-017-0431-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89864
in Space Science Reviews > vol 214 n° 1 (February 2018)[article]RAPTOR: Row and position tracheid organizer in R [technical note] / Richard L. Peters in Dendrochronologia, vol 47 (February 2018)
[article]
Titre : RAPTOR: Row and position tracheid organizer in R [technical note] Type de document : Article/Communication Auteurs : Richard L. Peters, Auteur ; Daniel Balanzategui, Auteur ; Alexander G. Hurley, Auteur ; Georg von Arx, Auteur ; Angela Luisa Prendin, Auteur ; Henri E. Cuny , Auteur ; Jesper Björklund, Auteur ; David Frank, Auteur ; Patrick Fonti, Auteur Année de publication : 2018 Projets : 3-projet - voir note / Article en page(s) : pp 10 - 16 Note générale : bbliographie
This work was funded by the Swiss National Science Foundation (Project LOTFOR no. 150205). DB used infra-structure of the Terrestrial Environmental Observatory (TERENO) of the Helmholtz Association and was supported by the Deutsche Forschungsgemeinschaft, DFG, project number HE 7220/1-1.Langues : Anglais (eng) Descripteur : [Termes IGN] fonctionnalité
[Termes IGN] R (langage)Résumé : (auteur) Mechanistic understanding of tree-ring formation and its modelling requires a cellular-based and spatially organized characterization of a tree ring, moving from whole rings, to intra-annual growth zones and individual cells. A tracheidogram is a radial profile of conifer anatomical features, such as lumen area and cell wall thickness, of sequentially- and positionally-ranked tracheids. However, its construction is tedious and time-consuming since image-analysis-based measurements do not recognize the position of cells within a radial file, and present-day tracheidograms must be constructed manually.
Here we present the R-package RAPTOR that complements tracheid anatomical data obtained from quantitative wood anatomy software (e.g., ROXAS, WinCELL, ImageJ), with the specific positional information necessary for the automated construction of tracheidograms. The package includes functions to read and visualize tracheid anatomical data, and uses local search algorithms to ascribe a ranked position to each tracheid in identified radial files. The package also provides functions to ensure that tracheids are adequately aligned for identifying the first tracheid in each radial file, and obtaining the correct ranking of tracheids along each radial file. Additional functions allow automating the analyses for multiple samples and rings (batch mode) and exporting data and plots for quality control.
RAPTOR allows tracheidogram users to take advantage of the latest generation of cell anatomical measuring systems. With this R-package we aim to facilitate the construction of more robust and versatile tracheidograms for the benefit of the research community.Numéro de notice : A2018-666 Affiliation des auteurs : IGN+Ext (2012-2019) Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.dendro.2017.10.003 Date de publication en ligne : 15/11/2017 En ligne : https://doi.org/10.1016/j.dendro.2017.10.003 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94257
in Dendrochronologia > vol 47 (February 2018) . - pp 10 - 16[article]Evaluation of photogrammetric block orientation using quality descriptors from statistically filtered tie points / Alessio Calantropio (2018)
Titre : Evaluation of photogrammetric block orientation using quality descriptors from statistically filtered tie points Type de document : Article/Communication Auteurs : Alessio Calantropio, Auteur ; Marc Pierrot-Deseilligny , Auteur ; Fulvio Rinaudo, Auteur ; Ewelina Rupnik , Auteur Editeur : International Society for Photogrammetry and Remote Sensing ISPRS Année de publication : 2018 Collection : International Archives of Photogrammetry, Remote Sensing and Spatial Information Sciences, ISSN 1682-1750 num. 42-2 Projets : 3-projet - voir note / Conférence : ISPRS 2018, TC II Mid-term Symposium, Towards Photogrammetry 2020 04/06/2018 07/06/2018 Riva del Garda Italie ISPRS OA Archives Importance : pp 185 - 191 Format : 21 x 30 cm Note générale : bibliographie
This work was supported and funded by the GAMHer project (Geomatics data Acquisition and Management for landscape and built Heritage in a European perspective), a 3-year project financed under the Italian PRIN 2015 framework (Progetti di Ricerca di Rilevante Interesse Nazionale).Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique
[Termes IGN] bloc d'images
[Termes IGN] chaîne de traitement
[Termes IGN] étalonnage de capteur (imagerie)
[Termes IGN] MicMac
[Termes IGN] modélisation 3D
[Termes IGN] orientation relative
[Termes IGN] photogrammétrie métrologique
[Termes IGN] points homologues
[Termes IGN] qualité des données
[Termes IGN] reconstruction 3DRésumé : (auteur) Due to the increasing number of low-cost sensors, widely accessible on the market, and because of the supposed granted correctness of the semi-automatic workflow for 3D reconstruction, highly implemented in the recent commercial software, more and more users operate nowadays without following the rigorousness of classical photogrammetric methods. This behaviour often naively leads to 3D products that lacks metric quality assessment. This paper proposes and analyses an approach that gives the users the possibility to preserve the trustworthiness of the metric information inherent in the 3D model, without sacrificing the automation offered by modern photogrammetry software. At the beginning, the importance of Data Quality Assessment is outlined, together with some recall of photogrammetry best practices. With the purpose of guiding the user through a correct pipeline for a certified 3D model reconstruction, an operative workflow is proposed, focusing on the first part of the object reconstruction steps (tie-points extraction, camera calibration, and relative orientation). A new GUI (Graphical User Interface) developed for the open source MicMac suite is then presented, and a sample dataset is used for the evaluation of the photogrammetric block orientation using statistically obtained quality descriptors. The results and the future directions are then presented and discussed. Numéro de notice : C2018-044 Affiliation des auteurs : LASTIG MATIS+Ext (2012-2019) Thématique : IMAGERIE Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : 10.5194/isprs-archives-XLII-2-185-2018 Date de publication en ligne : 30/05/2018 En ligne : https://doi.org/10.5194/isprs-archives-XLII-2-185-2018 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91262 MICROSCOPE mission: First results of a space test of the equivalence principle / Pierre Touboul in Physical Review Letters, vol 119 n° 3 (December 2017)
[article]
Titre : MICROSCOPE mission: First results of a space test of the equivalence principle Type de document : Article/Communication Auteurs : Pierre Touboul, Auteur ; Gilles Métris, Auteur ; Manuel Rodrigues, Auteur ; Yves André, Auteur ; Quentin Baghi, Auteur ; Joel Bergé, Auteur ; Damien Boulanger, Auteur ; Stefanie Bremer, Auteur ; Isabelle Panet , Auteur ; et al., Auteur Année de publication : 2017 Projets : 3-projet - voir note / Article en page(s) : n° 231101 Note générale : bibliographie
This work is based on observations made with the T-SAGE instrument, installed on the CNES-ESA-ONERA-CNRS-OCA-DLR-ZARM Microscope mission. ONERA authors’ work is financially supported by CNES and in-ternal funding. Authors from OCA have been supported by OCA, CNRS and CNES. ZARM authors’ work is sup-ported by the German Space Agency of DLR with funds of the BMWi (FKZ 50 OY 1305) and by the Deutsche Forschungsgemeinschaft DFG (LA 905/12-1).Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Missions spatiales
[Termes IGN] force de gravitation
[Termes IGN] MICROSCOPE (mission)
[Termes IGN] mission spatiale
[Termes IGN] principe d'équivalence
[Termes IGN] relativité généraleRésumé : (auteur) According to the weak equivalence principle, all bodies should fall at the same rate in a gravitational field. The MICROSCOPE satellite, launched in April 2016, aims to test its validity at the 10−15 precision level, by measuring the force required to maintain two test masses (of titanium and platinum alloys) exactly in the same orbit. A nonvanishing result would correspond to a violation of the equivalence principle, or to the discovery of a new long-range force. Analysis of the first data gives δ(Ti,Pt)=[−1±9(stat)±9(syst)]×10−15 (1σ statistical uncertainty) for the titanium-platinum Eötvös parameter characterizing the relative difference in their free-fall accelerations. Numéro de notice : A2017-867 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Autre URL associée : vers ArXiv Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1103/PhysRevLett.119.231101 Date de publication en ligne : 04/12/2017 En ligne : https://doi.org/10.1103/PhysRevLett.119.231101 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89880
in Physical Review Letters > vol 119 n° 3 (December 2017) . - n° 231101[article]A scalable and multi-purpose point cloud server (PCS) for easier and faster point cloud data management and processing / Rémi Cura in ISPRS Journal of photogrammetry and remote sensing, vol 127 (May 2017)PermalinkSemi-parametric segmentation of multiple series using a DP-Lasso strategy / Karine Bertin in Journal of Statistical Computation and Simulation, vol 87 n° 6 (2017)PermalinkThe scale of VGI in map production: A perspective on European national mapping agencies / Ana-Maria Olteanu-Raimond in Transactions in GIS, vol 21 n° 1 (February 2017)PermalinkPermalinkAirborne lidar estimation of aboveground forest biomass in the absence of field inventory / António Ferraz in Remote sensing, vol 8 n° 8 (August 2016)PermalinkReconstruction of itineraries from annotated text with an informed spanning tree algorithm / Ludovic Moncla in International journal of geographical information science IJGIS, vol 30 n° 5-6 (May - June 2016)PermalinkReconstruction automatique d'itinéraires à partir de textes descriptifs / Ludovic Moncla in Cartes & Géomatique, n° 227 (mars - mai 2016)PermalinkAboveground-biomass estimation of a complex tropical forest in India using Lidar / Cédric Vega in Remote sensing, vol 7 n° 8 (August 2015)PermalinkAccuracy of unmodified Stokes’ integration in the R-C-R procedure for geoid computation / Zahra Ismaïl in Journal of applied geodesy, vol 9 n° 2 (June 2015)PermalinkL’apport des modélisations 3D pour l’étude de la grotte Blanchard (Saint-Marcel, Indre, France), bilan et perspectives pour l’analyse croisée des données / Eric Robert (2014)Permalink