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Weighted coordinate transformation formulated by standard least-squares theory / D. Mihajlovic in Survey review, vol 49 n° 356 (November 2017)  

Public [article]  inSurvey review > vol 49 n° 356 (November 2017) . - pp 328 - 345 Titre : Weighted coordinate transformation formulated by standard least-squares theory Type de document : Article/Communication Auteurs : D. Mihajlovic, Auteur ; Z. Cvijetinović, Auteur Année de publication : 2017 Article en page(s) : pp 328 - 345 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] méthode des moindres carrés [Termes IGN] pondération [Termes IGN] transformation de coordonnées Résumé : (Auteur) This paper presents a universal model of weighted coordinate transformation, i.e. transformation considering the errors of coordinates in both coordinate systems. It is intrinsically one of the typical examples of ‘error-in-variables’ (EIV) models. The proposed method of LS theory application on weighted coordinate transformation does not impose any constraints on the form of functional relationship among stochastic variables. Since the basic idea is to generalise Gauss–Markov model (GMM) by introduction of so-called ‘total residuals’, the proposed procedure is named ‘Generalised Gauss–Markov model’. Formulation of expressions for estimation of unknown transformation parameters is theoretically confirmed using the Gauss–Helmert model (GHM) and three different modifications of the GMM. The proposed procedure is in its essence a strict solution to total least-squares (unweighted) and weighted total least-squares problem in coordinate transformation. This thesis is experimentally confirmed by comparison of its results with those found in four characteristic examples from the literature. Numéro de notice : A2017-555 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/00396265.2016.1173329 En ligne : https://doi.org/10.1080/00396265.2016.1173329 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86616 [article]

Efficient weighted total least-squares solution for partial errors-in-variables model / J. Zhao in Survey review, vol 49 n° 356 (November 2017)  

Public [article]  inSurvey review > vol 49 n° 356 (November 2017) . - pp 346 - 354 Titre : Efficient weighted total least-squares solution for partial errors-in-variables model Type de document : Article/Communication Auteurs : J. Zhao, Auteur Année de publication : 2017 Article en page(s) : pp 346 - 354 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] itération [Termes IGN] méthode des moindres carrés Résumé : (Auteur) Due to great computation burden of the original computational formula for partial errors-in-variables (EIV), an alternative formula for parameter estimation in the partial EIV model was proposed to promote computational efficiency. Unfortunately, more iteration is required for obtaining the weighted total least-squares (WTLS) solution of the partial EIV model with above two formulae. Consequently, those methods are not proper for larger data problem in terms of computational efficiency. To circumvent this difficulty, a new formula and the fast algorithm are proposed based on the Lagrange extreme value method. Through some numerical examples with coordinate transformation, it is illustrated that the new developed method is an effective strategy to conduct the WTLS adjustment for the partial EIV model. The computational efficiency is significantly improved at least 80%. Numéro de notice : A2017-556 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/00396265.2016.1173329 En ligne : https://doi.org/10.1080/00396265.2016.1180753 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86617 [article]

Appraisal of the Hellenic Geodetic Reference System 1987 based on backward-transformed ITRF coordinates using a national velocity model / M. Chatzinikos in Survey review, vol 49 n° 356 (November 2017)  

Public [article]  inSurvey review > vol 49 n° 356 (November 2017) . - pp 386 - 398 Titre : Appraisal of the Hellenic Geodetic Reference System 1987 based on backward-transformed ITRF coordinates using a national velocity model Type de document : Article/Communication Auteurs : M. Chatzinikos, Auteur ; Christopher Kotsakis, Auteur Année de publication : 2017 Article en page(s) : pp 386 - 398 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] champ de vitesse [Termes IGN] géodynamique [Termes IGN] Grèce [Termes IGN] International Terrestrial Reference Frame [Termes IGN] transformation de coordonnées Résumé : (Auteur) The paper presents a detailed accuracy evaluation of the Hellenic Geodetic Reference System 1987 (HGRS87), a non-geocentric traditional local datum which was established thirty years ago and it is still used as the official coordinate system for surveying applications in Greece. This is the first time that a large-scale assessment of HGRS87 is performed, which aims to reveal its weakness by quantifying its consistency with a higher quality ITRF/GNSS-based frame over the entire country. A geodetic velocity model is employed in our analysis in an attempt to eliminate the accumulated geodynamical distortions of the (static) HGRS87 coordinates, and thus to provide a more judicious comparison between the underlying frames at a common epoch. Our results show that, even after removing the geodynamical distortions, the average accuracy of HGRS87 at national scale remains worse than 45 cm, yet significant variations exist in its regional accuracy level over different parts of Greece. Numéro de notice : A2017-557 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/00396265.2016.1180797 En ligne : https://doi.org/10.1080/00396265.2016.1180797 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86618 [article]