Survey review . vol 48 n° 350Paru le : 01/09/2016 |
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Ajouter le résultat dans votre panierUse of the gyrotheodolite in underground networks of long high-speed railway tunnels / J. Velasco-Gómez, in Survey review, vol 48 n° 350 (September 2016)
[article]
Titre : Use of the gyrotheodolite in underground networks of long high-speed railway tunnels Type de document : Article/Communication Auteurs : J. Velasco-Gómez,, Auteur ; J. F. Prieto, Auteur ; I. Molina, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 329 - 337 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] déviation de la verticale
[Termes IGN] Espagne
[Termes IGN] géoïde
[Termes IGN] guidage de forage
[Termes IGN] guidage de véhicules
[Termes IGN] gyrothéodolite
[Termes IGN] lever souterrain
[Termes IGN] tunnel
[Termes IGN] voie ferréeRésumé : (auteur) The quality of geodetic networks for guiding Tunnel Boring Machines (TBMs) inside long tunnels depends largely on the correct use of a gyroscope. These networks are based on a series of control points at the tunnel entrance, and link each station by means of survey observations as they advance along the tunnel. Once, the networks are used to guide the TBM, they are no longer checked again. It is necessary to perform high accuracy astronomical observations to stars in order to determine the gyrotheodolite constant. Since astronomical observations cannot be made inside tunnels, geodetic azimuths have to be used for the computations. However, these azimuths cannot theoretically be compared with the astronomical azimuths obtained by the gyrotheodolite. An alternative is to compute the instrument constant using the values of the deviation of the vertical derived from a geoid model. That is the approach used in this work where a methodology for the design of underground networks in long tunnels is also presented. This procedure has been implemented during the construction of the Guadarrama and Pajares high-speed railway tunnels (Spain). Numéro de notice : A2016-640 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1179/1752270615Y.0000000043 En ligne : https://doi.org/10.1179/1752270615Y.0000000043 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81845
in Survey review > vol 48 n° 350 (September 2016) . - pp 329 - 337[article]Recovery of cadastral boundaries with GNSS equipment / A. Cina in Survey review, vol 48 n° 350 (September 2016)
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Titre : Recovery of cadastral boundaries with GNSS equipment Type de document : Article/Communication Auteurs : A. Cina, Auteur ; A. M. Manzino, Auteur ; G. Manzino, Auteur Année de publication : 2016 Article en page(s) : pp 338 - 346 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Cadastre étranger
[Termes IGN] appariement de données localisées
[Termes IGN] cadastre ancien
[Termes IGN] cadastre numérique
[Termes IGN] ellipsoïde de Bessel
[Termes IGN] Italie
[Termes IGN] limite cadastrale
[Termes IGN] numérisation du cadastre
[Termes IGN] positionnement par GNSS
[Termes IGN] projection
[Termes IGN] système de référence localRésumé : (auteur) The purpose of this work is to propose a new redefinition of cadastral boundaries using GNSS equipment and cadastral maps. These maps are the ‘original’ maps of the Italian Land Cadastre, the first cartographic support built directly from measures carried out by technicians during implantation of the Italian land cadastre. They are called ‘originali di impianto’ – ‘originals of implantation’ or ‘implant maps’. As such, these maps are valuable and are kept with great care. Recently, the Italian cadastre has carried out an accurate digitisation of these maps in a raster format at a high resolution. In this work, the authors propose the use of these digital maps for the recovery of cadastral boundary. The original cadastral map, one of the primary sources relied upon in defining legal boundaries, generally uses the Bessel ellipsoid localised in Genova and the Cassini-Soldner projection; the GNSS equipment, on the other hand, uses the geocentric ellipsoid with global or continental realisations. After an RTK positioning, the receivers usually provide the cartographic coordinates in a Gauss projection. However, our study deals with the problem of using different projections and reference systems within the limits of a map. In this context, the transition between systems and projections can be made through a conformal transformation with deformations slighter than graphical errors in the map. The difficulty of finding identifiable points in both reference systems is partially solved through a new way of carrying out the redefinition of boundaries by exploiting geometric information. Numéro de notice : A2016-641 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/POSITIONNEMENT Nature : Article DOI : 10.1179/1752270615Y.0000000007 En ligne : https://doi.org/10.1179/1752270615Y.0000000007 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81846
in Survey review > vol 48 n° 350 (September 2016) . - pp 338 - 346[article]Real-time cycle-slip detection and repair for BeiDou triple-frequency undifferenced observations / Y.-F. Yao in Survey review, vol 48 n° 350 (September 2016)
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Titre : Real-time cycle-slip detection and repair for BeiDou triple-frequency undifferenced observations Type de document : Article/Communication Auteurs : Y.-F. Yao, Auteur ; J.-X. Gao, Auteur ; J. Wang, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 367 - 375 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] détection d'anomalie
[Termes IGN] glissement de cycle
[Termes IGN] phase
[Termes IGN] positionnement par BeiDou
[Termes IGN] récepteur trifréquence
[Termes IGN] signal BeiDou
[Termes IGN] temps réelRésumé : (auteur) A new method of real-time cycle-slip detection and repair for BeiDou navigation satellite system (BDS) triple-frequency undifferenced observations is proposed. The method, which is based on code–phase and geometry-free phase combinations, composes linearly independent combination observations to uniquely determine the cycle-slip of original frequency phase observations in two independent steps. First, two extra-wide lane (EWL) code–phase combinations are utilised to determine the EWL combination cycle-slips. The sum of the carrier phase combination coefficients is zero. Second, the geometry-free phase combination with a non-zero sum of combination coefficients composes linearly independent combination observations with two code–phase combinations. Ionospheric delay variance systematic deviation is corrected with several previous carrier-phase observations without cycle-slip, which seriously affect the accuracy of the geometry-free phase combination observations. The BDS triple-frequency carrier-phase and code observations of different satellite types at 30 s sampling interval, which involve increased active ionospheric conditions in 1 day, are utilised to test the method. Results show that the proposed method can efficiently detect and accurately repair any cycle-slip combinations in real-time for different satellite types under active ionospheric conditions. No erroneous and leakage judgments are observed in the test. Numéro de notice : A2016-642 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/00396265.2015.1133518 En ligne : https://doi.org/10.1080/00396265.2015.1133518 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81847
in Survey review > vol 48 n° 350 (September 2016) . - pp 367 - 375[article]The SMITSWAM method of datum transformations consisting of Standard Molodensky in two stages with applied misclosures / Andrew Carey Ruffhead in Survey review, vol 48 n° 350 (September 2016)
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Titre : The SMITSWAM method of datum transformations consisting of Standard Molodensky in two stages with applied misclosures Type de document : Article/Communication Auteurs : Andrew Carey Ruffhead, Auteur Année de publication : 2016 Article en page(s) : pp 376 - 384 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] approximation
[Termes IGN] ellipsoïde (géodésie)
[Termes IGN] transformation de coordonnéesRésumé : (auteur) For three-parameter datum transformations to be applied rigorously, geodetic coordinates on the first ellipsoid need to be converted to Cartesian coordinates before application of the shifts, then converted to geodetic coordinates on the second ellipsoid. The Standard Molodensky method of datum transformation is more direct but is inexact. It also fails to reproduce the original coordinates when applied forward and back. However, this paper shows a pattern of proportionality between the misclosures and the errors in the forward approximations. This gives rise to a new method of computing the transformations, best described as “Standard Molodensky in two stages with applied misclosures” (SMITSWAM). The method is shown to be more than 1600 times more accurate than Standard Molodensky, coming close to the accuracy of the rigorous approach. SMITSWAM is also shown to be around 48% faster than the traditional form of the rigorous method which uses iteration. Numéro de notice : A2016-643 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/00396265.2016.1191748 En ligne : https://doi.org/10.1080/00396265.2016.1191748 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81848
in Survey review > vol 48 n° 350 (September 2016) . - pp 376 - 384[article]