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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]

Generalized inner constraints for geodetic network densification problems / Christopher Kotsakis in Journal of geodesy, vol 87 n° 7 (July 2013)  

Public [article]  inJournal of geodesy > vol 87 n° 7 (July 2013) . - pp 661 - 673 Titre : Generalized inner constraints for geodetic network densification problems Type de document : Article/Communication Auteurs : Christopher Kotsakis, Auteur Année de publication : 2013 Article en page(s) : pp 661 - 673 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] contrainte d'intégrité [Termes IGN] densification géodésique [Termes IGN] réseau géodésique Résumé : (Auteur) The estimated coordinates from a minimum-constrained (MC) network adjustment are generally influenced by two different error sources, that is the data noise from the available measurements and the so-called datum noise due to random errors in the fiducial coordinates that are used for the datum definition with regard to an external reference frame. Although the latter source does not affect the estimable characteristics of a MC solution, it still contributes a datum-related noise to the estimated positions which reflects the uncertainty of the coordinate system itself for the adjusted network. The aim of this paper is to develop a new type of MCs which minimizes both of the aforementioned effects in the final coordinates of an adjusted network. This particular problem has not been treated in the geodetic literature and the solution which is presented herein offers an elegant unification of the classic inner constraints into a more general framework for the datum choice problem of network optimization theory. Furthermore, the findings of our study provide a useful and rigorous tool for frame densification problems by means of an optimal MC adjustment in geodetic networks. Numéro de notice : A2013-400 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-013-0637-0 Date de publication en ligne : 23/05/2013 En ligne : https://doi.org/10.1007/s00190-013-0637-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32538 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2013071	SL	Revue	Centre de documentation	Revues en salle	Disponible

Estimation of the zero-height geopotential level WoLVD in a local vertical datum from inversion of co-located GPS, leveling and geoid heights: a case study in the Hellenic islands / Christopher Kotsakis in Journal of geodesy, vol 86 n° 6 (June 2012)  

Public [article]  inJournal of geodesy > vol 86 n° 6 (June 2012) . - pp 423 - 439 Titre : Estimation of the zero-height geopotential level WoLVD in a local vertical datum from inversion of co-located GPS, leveling and geoid heights: a case study in the Hellenic islands Type de document : Article/Communication Auteurs : Christopher Kotsakis, Auteur ; K. Katsambalos, Auteur ; Dimitrios Ampatzidis, Auteur Année de publication : 2012 Article en page(s) : pp 423 - 439 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] champ de pesanteur terrestre [Termes IGN] Egée, mer [Termes IGN] Grèce [Termes IGN] modèle de géopotentiel local [Termes IGN] niveau moyen des mers [Termes IGN] réseau altimétrique local [Termes IGN] zéro hydrographique Résumé : (Auteur) The estimation of the zero-height geopotential level of a local vertical datum (LVD) is a key task towards the connection of isolated physical height frames and their unification into a common vertical reference system. Such an estimate resolves, in principle, the ‘ambiguity’ of a traditional crust-fixed LVD by linking it with a particular equipotential surface of Earth’s gravity field under the presence of an external geopotential model. The aim of this paper is to study the estimation scheme that can be followed for solving the aforementioned problem based on the joint inversion of co-located GPS and leveling heights in conjunction with a fixed Earth gravity field model. Several case studies with real data are also presented that provide, for the first time, precise estimates of the LVD offsets for a number of Hellenic islands across the Aegean and Ionian Sea. Numéro de notice : A2012-244 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0530-7 Date de publication en ligne : 03/12/2011 En ligne : https://doi.org/10.1007/s00190-011-0530-7 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31690 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2012061	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Hellenic terrestrial reference system 2007 (HTRS07): a regional realization of ETRS89 over Greece in support of HEPOS / K. Katsampalos in Bulletin of geodesy and geomatics BGG, vol 69 n° 2 - 3 (December 2010)

Public [article]  inBulletin of geodesy and geomatics BGG > vol 69 n° 2 - 3 (December 2010) . - pp 329 - 347 Titre : Hellenic terrestrial reference system 2007 (HTRS07): a regional realization of ETRS89 over Greece in support of HEPOS Type de document : Article/Communication Auteurs : K. Katsampalos, Auteur ; Christopher Kotsakis, Auteur ; M. Gianniou, Auteur Année de publication : 2010 Article en page(s) : pp 329 - 347 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] compensation par moindres carrés [Termes IGN] European Terrestrial Reference System 1989 [Termes IGN] Grèce [Termes IGN] HEPOS [Termes IGN] précision décimétrique [Termes IGN] station permanente [Termes IGN] système de référence local [Termes IGN] transformation de coordonnées Résumé : (Auteur) An overview of a regional realization of ETRS89 over the area of Greece is presented in this paper. The underlying project is related to the recent establishment of the Hellenic Positioning System (HEPOS), a GPS-based spatial positioning service using a network of 98 continuously operating reference stations located in Greece and operated by KTIMATOLOGIO S.A. The data analysis procedure that was followed for the least-squares adjustment of the HEPOS network is described, along with the adopted methodology for the datum definition and its alignment with the ETRS89/ETRF05 reference frame. The paper presents also a combined transformation model that was concurrently developed for the connection between the official Hellenic Geodetic Reference System 1987 (HGRS87) and the Hellenic Terrestrial Reference System 2007 (HTRS07), where the latter identifies the ETRS89/ETRF05-based frame that underlies the operation of HEPOS. The results obtained from the evaluation of the aforementioned model, at 2430 geodetic benchmarks throughout Greece, revealed an accuracy level that is better than 10 cm in terms of the rms value for the total horizontal transformation error. Numéro de notice : A2010-497 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31336 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
013-2010021	RAB	Revue	Centre de documentation	En réserve L003	Disponible

A study reference frame consistency in recent Earth gravitational models / Christopher Kotsakis in Journal of geodesy, vol 83 n° 1 (January 2009)  

Public [article]  inJournal of geodesy > vol 83 n° 1 (January 2009) . - pp 31 - 50 Titre : A study reference frame consistency in recent Earth gravitational models Type de document : Article/Communication Auteurs : Christopher Kotsakis, Auteur Année de publication : 2009 Article en page(s) : pp 31 - 50 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] champ de pesanteur terrestre [Termes IGN] cohérence des données [Termes IGN] Earth Gravity Model 2008 [Termes IGN] GRACE [Termes IGN] harmonique sphérique [Termes IGN] levé gravimétrique [Termes IGN] modèle de géopotentiel [Termes IGN] repère de référence Résumé : (Auteur) All gravity field functionals obtained from an Earth gravitational model (EGM) depend on the underlying terrestrial reference frame (TRF), with respect to which the EGM’s spherical harmonic coefficients refer to. In order to maintain a coherent framework for the comparison of current and future EGMs, it is thus important to investigate the consistency of their inherent TRFs, especially when their use is intended for high precision studies. Following the methodology described in an earlier paper by Kleusberg (1980), the similarity transformation parameters between the associated reference frames for several EGMs (including the most recent CHAMP/GRACE models at the time of writing this paper) are estimated in the present study. Specifically, the differences between the spherical harmonic coefficients for various pairs of EGMs are parameterized through a 3D-similarity spatial transformation model that relates their underlying TRFs. From the least-squares adjustment of such a parametric model, the origin, orientation and scale stability between the EGMs’ reference frames can be identified by estimating their corresponding translation, rotation and scale factor parameters. Various aspects of the estimation procedure and its results are highlighted in the paper, including data weighting schemes, the sensitivity of the results with respect to the selected harmonic spectral band, the correlation structure and precision level of the estimated transformation parameters, the effect of the estimated differences of the EGMs’ reference frames on their height anomaly signal, and the overall feasibility of Kleusberg’s formulae for the assessment of TRF inconsistencies among global geopotential models. Copyright Springer Numéro de notice : A2009-180 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-008-0227-8 En ligne : https://doi.org/10.1007/s00190-008-0227-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29810 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-09011	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-09012	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Transforming ellipsoidal heights and geoid undulations between different geodetic reference frames / Christopher Kotsakis in Journal of geodesy, vol 82 n° 4-5 (April - May 2008)  

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A new Canadian geoid model in support of levelling by GPS / Georgia Fotopoulos in Geomatica, vol 54 n° 1 (March 2000)  

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