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Improved area-based deformation analysis of a radio telescope’s main reflector based on terrestrial laser scanning / Christoph Holst in Journal of applied geodesy, vol 9 n° 1 (March 2015)  

Public [article]  inJournal of applied geodesy > vol 9 n° 1 (March 2015) . - pp 1 - 14 Titre : Improved area-based deformation analysis of a radio telescope’s main reflector based on terrestrial laser scanning Type de document : Article/Communication Auteurs : Christoph Holst, Auteur ; Axel Nothnagel, Auteur ; Martin Blome, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 1 - 14 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] auto-étalonnage [Termes IGN] déformation d'édifice [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] radiotélescope [Termes IGN] segmentation [Termes IGN] semis de points Résumé : (auteur) The main reflectors of radio telescopes deform due to gravitation when changing their elevation angle. This can be analyzed by scanning the paraboloid surface with a terrestrial laser scanner and by determining focal length variations and local deformations from best-fit approximations. For the Effelsberg radiotelescope, both groups of deformations are estimated from seven points clouds measured at different elevation angles of the telescope: the focal length decreases by 22.7 mm when tilting the telescope from 90 deg to 7.5 deg elevation angle. Variable deformations of ± 2 mm are detected as well at certain areas. Furthermore, a few surface panels seem to be misaligned. Apart from these results, the present study highlights the need for an appropriate measurement concept and for preprocessing stepswhen using laser scanners for area-based deformation analyses. Especially, data reduction, object segmentation and laser scanner calibration are discussed in more detail. An omission of these steps would significantly degrade the deformation analysis and the significance of its results. This holds for all sorts of laser scanner based analyses. Numéro de notice : A2015-026 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article DOI : 10.1515/jag-2014-0018 En ligne : http://www.degruyter.com/view/j/jag.2015.9.issue-1/jag-2014-0018/jag-2014-0018.x [...] Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76879 [article]