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AUSGeoid2020 combined gravimetric–geometric model : location-specific uncertainties and baseline-length-dependent error decorrelation / Nicholas J. Brown in Journal of geodesy, vol 92 n° 12 (December 2018)  

Public [article]  inJournal of geodesy > vol 92 n° 12 (December 2018) . - pp 1457 - 1465 Titre : AUSGeoid2020 combined gravimetric–geometric model : location-specific uncertainties and baseline-length-dependent error decorrelation Type de document : Article/Communication Auteurs : Nicholas J. Brown, Auteur ; Jack C. McCubbine, Auteur ; Will E. Featherstone, Auteur ; N. Gowans, Auteur ; A. Woods, Auteur ; et al., Auteur Année de publication : 2018 Article en page(s) : pp 1457 - 1465 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] anomalie de pesanteur [Termes IGN] Australian Height Datum [Termes IGN] Australie [Termes IGN] géoïde gravimétrique [Termes IGN] géoïde local [Termes IGN] incertitude relative [Termes IGN] quasi-géoïde Résumé : (Auteur) AUSGeoid2020 is a combined gravimetric–geometric model (sometimes called a “hybrid quasigeoid model”) that provides the separation between the Geocentric Datum of Australia 2020 (GDA2020) ellipsoid and Australia’s national vertical datum, the Australian Height Datum (AHD). This model is also provided with a location-specific uncertainty propagated from a combination of the levelling, GPS ellipsoidal height and gravimetric quasigeoid data errors via least squares prediction. We present a method for computing the relative uncertainty (i.e. uncertainty of the height between any two points) between AUSGeoid2020-derived AHD heights based on the principle of correlated errors cancelling when used over baselines. Results demonstrate AUSGeoid2020 is more accurate than traditional third-order levelling in Australia at distances beyond 3 km, which is 12 mm of allowable misclosure per square root km of levelling. As part of the above work, we identified an error in the gravimetric quasigeoid in Port Phillip Bay (near Melbourne in SE Australia) coming from altimeter-derived gravity anomalies. This error was patched using alternative altimetry data. Numéro de notice : A2018-587 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1202-7 Date de publication en ligne : 27/08/2018 En ligne : https://doi.org/10.1007/s00190-018-1202-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92497 [article]

Hyper redundancy for accuracy enhancement in automated close range photogrammetry / Clive Simpson Fraser in Photogrammetric record, vol 20 n° 111 (September - November 2005)  

Public [article]  inPhotogrammetric record > vol 20 n° 111 (September - November 2005) . - pp 205 - 217 Titre : Hyper redundancy for accuracy enhancement in automated close range photogrammetry Type de document : Article/Communication Auteurs : Clive Simpson Fraser, Auteur ; A. Woods, Auteur ; D. Brizzi, Auteur Année de publication : 2005 Article en page(s) : pp 205 - 217 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie terrestre [Termes IGN] acquisition de données [Termes IGN] antenne [Termes IGN] déformation d'édifice [Termes IGN] image multiple [Termes IGN] photogrammétrie métrologique [Termes IGN] photographie terrestre [Termes IGN] précision des mesures [Termes IGN] radiotélescope [Termes IGN] redondance de données [Termes IGN] visualisation 3D Résumé : (Auteur) A generic network design in close range photogrammetry is one where optimal multi-ray intersection geometry is obtained with as few camera stations as practicable. Hyper redundancy is a concept whereby, once the generic network is in place, many additional images are recorded, with the beneficial impact upon object point precision being equivalent to the presence of multiple exposures at each camera position within the generic network. The effective number of images per station within a hyper redundant network might well be in the range of 10 to 20 or more. As is apparent when it is considered that a hyper redundant network may comprise hundreds of images, the concept is only applicable in practice to fully automatic vision metrology systems, where it proves to be a very effective means of enhancing measurement accuracy at the cost of minimal additional work in the image recording phase. This paper briefly reviews the network design and accuracy aspects of hyper redundancy and illustrates the technique by way of the photogrammetric measurement of surface deformation of a radio telescope of 26 m diameter. This project required an object point measurement accuracy of = 0.065 mm, or 1/400 000 of the diameter of the reflector. Numéro de notice : A2005-377 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2005.00327.x En ligne : https://doi.org/10.1111/j.1477-9730.2005.00327.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27513 [article]

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