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Deformation analysis of a reference wall towards the uncertainty investigation of terrestrial laser scanners / Berit Schmitz in Journal of applied geodesy, vol 15 n° 3 (July 2021)  

Public [article]  inJournal of applied geodesy > vol 15 n° 3 (July 2021) . - pp 189-206 Titre : Deformation analysis of a reference wall towards the uncertainty investigation of terrestrial laser scanners Type de document : Article/Communication Auteurs : Berit Schmitz, Auteur ; Heiner Kuhlmann, Auteur ; Christoph Holst, Auteur Année de publication : 2021 Article en page(s) : pp 189-206 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] déformation d'édifice [Termes IGN] déformation géométrique [Termes IGN] données laser [Termes IGN] incertitude géométrique [Termes IGN] matrice de covariance [Termes IGN] modèle de déformation tectonique [Termes IGN] modèle stochastique [Termes IGN] mur [Termes IGN] qualité des données [Termes IGN] tachéomètre électronique [Termes IGN] télémètre laser terrestre Résumé : (Auteur) The perfect knowledge about the scanned object’s geometry is essential for the empirical analysis of the stochastic properties of terrestrial laser scanners (TLSs). The Bonn reference wall is intended to be used as a reference for TLS quality investigations. Therefore, it is necessary to know the geometry of the wall at each time of scanning to avoid the misinterpretation of possible movements as systematic effects in the scanner. For this reason, we investigate the stability of the Bonn reference wall in this study. This includes the definition of a geodetic datum, the quantification of displacements, and the establishment of a suited deformation model. Since we discover a movement of about 1 mm within one day and up to 7 mm over the year, it is necessary to establish a cause-response deformation model to correct the wall movements in the scans. This study proposes two dynamic deformation models to compensate for the movements of the wall within one day and within a year. Our results show that it is better to measure the initial geometry of the wall each day since 89 % of the relative movements can be reduced to a maximum of 0.25 mm with a standard deviation of 0.16 mm (0.23 mm without modeling). If the shape is not initially known each day, the standard deviation of the displacements can be reduced from 1.10 mm to 0.61 mm, but the largest residuals still amount up to 2.5 mm, which is not sufficient for stochastic TLS investigations. Numéro de notice : A2021-467 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jag-2020-0025 Date de publication en ligne : 25/03/2021 En ligne : https://doi.org/10.1515/jag-2020-0025 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98103 [article]

Temperature and humidity effects on CG-6 gravity observations / P. I. A. Weerasinghe in Journal of applied geodesy, vol 15 n° 3 (July 2021)  

Public [article]  inJournal of applied geodesy > vol 15 n° 3 (July 2021) . - pp 225 - 231 Titre : Temperature and humidity effects on CG-6 gravity observations Type de document : Article/Communication Auteurs : P. I. A. Weerasinghe, Auteur ; Herath Mudiyanselage Indika Prasanna, Auteur Année de publication : 2021 Article en page(s) : pp 225 - 231 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] corrélation linéaire [Termes IGN] force de gravitation [Termes IGN] gravimètre [Termes IGN] humidité de l'air [Termes IGN] instrument de mesure [Termes IGN] Sri Lanka [Termes IGN] température de l'air [Termes IGN] thermomètre Résumé : (Auteur) The CG6 is an automated gravity meter that has a worldwide measurement range of over 8000 mGals and a reading resolution of 0.0001 mGal. Some factors that may influence the gravity readings are corrected by the instrument’s software. In this paper, the effects of the ambient temperature and humidity changes on the CG-6’s gravity measurements were investigated with the aim of reducing the uncertainty which remains in gravity measurements in microgal level, and giving recommendations for more accurate results. A controlled heating experiment was used to determine the impact of ambient temperature on gravity and 12 hours of continuous gravity observations were used to identify the impact of humidity on gravity measurements. It was observed that the sensor temperature and the gravity reading were highly correlated with the ambient temperature. The linear correlation with R2 > 0.94 and R2 > 0.90 were found for the corrected gravity reading and the residual sensor temperature variations respectively with the ambient temperature when heating. It was demonstrated that the calculated ambient temperature correction, −0.0011 mGal/oC, is more stable than the correction given by the instrument in terms of standard deviation though the impact of humidity on gravity reading was not clear. Numéro de notice : A2021-468 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jag-2020-0047 Date de publication en ligne : 28/04/2021 En ligne : https://doi.org/10.1515/jag-2020-0047 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98106 [article]

Comparison of polar ionospheric behavior at Arctic and Antarctic regions for improved satellite-based positioning / Arun Kumar Singh in Journal of applied geodesy, vol 15 n° 3 (July 2021)  

Public [article]  inJournal of applied geodesy > vol 15 n° 3 (July 2021) . - pp 269 - 277 Titre : Comparison of polar ionospheric behavior at Arctic and Antarctic regions for improved satellite-based positioning Type de document : Article/Communication Auteurs : Arun Kumar Singh, Auteur Année de publication : 2021 Article en page(s) : pp 269 - 277 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] amplitude [Termes IGN] Antarctique [Termes IGN] Arctique [Termes IGN] champ géomagnétique [Termes IGN] ionosphère [Termes IGN] magnétosphère [Termes IGN] phase [Termes IGN] pôle [Termes IGN] positionnement par GNSS [Termes IGN] retard ionosphèrique [Termes IGN] scintillation [Termes IGN] teneur totale en électrons [Termes IGN] variation temporelle Résumé : (Auteur) In this paper, we investigate the hemispheric symmetric and asymmetric characteristics of ionospheric total electron content (TEC) and its dependency on the interplanetary magnetic field (IMF) in the northern and southern polar ionosphere. The changes in amplitude and phase scintillation are also probed through Global Ionospheric Scintillation and TEC monitoring (GISTM) systems recordings at North pole [Himadri station; Geographic 78°55′ N, 11°56′ E] and South pole [Maitri station; Geographic 70°46′ S 11°44′ E]. Observations show the range of %TEC variability being relatively more over Antarctic region (−40 % to 60 %) than Arctic region (−25 % to 25 %), corroborating the role of the dominant solar photoionization production process. Our analysis confirms that TEC variation at polar latitudes is a function of magnetosphere-ionosphere coupling, depending on interplanetary magnetic field (IMF) orientation and magnitude in the X ( Bx), Y ( By), and Z ( Bz) plane. Visible enhancement in TEC is noticed in the northern polar latitude when Bx6nT and Bz>0 whereas the southern polar latitude perceives TEC enhancements with Bx>0, −6nT Numéro de notice : A2021-469 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jag-2021-0033 Date de publication en ligne : 22/06/2021 En ligne : https://doi.org/10.1515/jag-2021-0033 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98107 [article]