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Tuning a gravimetric quasigeoid to GPS-levelling by non-stationary least-squares collocation / N. Darbehesti in Journal of geodesy, vol 84 n° 7 (July 2010)  

Public [article]  inJournal of geodesy > vol 84 n° 7 (July 2010) . - pp 419 - 431 Titre : Tuning a gravimetric quasigeoid to GPS-levelling by non-stationary least-squares collocation Type de document : Article/Communication Auteurs : N. Darbehesti, Auteur ; Will E. Featherstone, Auteur Année de publication : 2010 Article en page(s) : pp 419 - 431 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] appariement de données localisées [Termes IGN] collocation par moindres carrés [Termes IGN] géoïde altimétrique [Termes IGN] géoïde gravimétrique [Termes IGN] géoïde local [Termes IGN] nivellement par GPS [Termes IGN] Perth Résumé : (Auteur) This paper addresses implementation issues in order to apply non-stationary least-squares collocation (LSC) to a practical geodetic problem: fitting a gravimetric quasigeoid to discrete geometric quasigeoid heights at a local scale. This yields a surface that is useful for direct GPS heighting. Non-stationary covariance functions and a non-stationary model of the mean were applied to residual gravimetric quasigeoid determination by planar LSC in the Perth region of Western Australia. The non-stationary model of the mean did not change the LSC results significantly. However, elliptical kernels in non-stationary covariance functions were used successfully to create an iterative optimisation loop to decrease the difference between the gravimetric quasigeoid and geometric quasigeoid at 99 GPS-levelling points to a user-prescribed tolerance. Numéro de notice : A2010-301 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0377-3 Date de publication en ligne : 18/04/2010 En ligne : https://doi.org/10.1007/s00190-010-0377-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30495 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2010071	SL	Revue	Centre de documentation	Revues en salle	Disponible

Integer least-squares theory for the GNSS compass / Peter J.G. Teunissen in Journal of geodesy, vol 84 n° 7 (July 2010)  

Public [article]  inJournal of geodesy > vol 84 n° 7 (July 2010) . - pp 433 - 447 Titre : Integer least-squares theory for the GNSS compass Type de document : Article/Communication Auteurs : Peter J.G. Teunissen, Auteur Année de publication : 2010 Article en page(s) : pp 433 - 447 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] altitude [Termes IGN] ambiguïté entière [Termes IGN] données GNSS [Termes IGN] méthode des moindres carrés [Termes IGN] positionnement par GNSS [Termes IGN] résolution d'ambiguïté Résumé : (Auteur) Global navigation satellite system (GNSS) carrier phase integer ambiguity resolution is the key to high precision positioning and attitude determination. In this contribution, we develop new integer least-squares (ILS) theory for the GNSS compass model, together with efficient integer search strategies. It extends current unconstrained ILS theory to the nonlinearly constrained case, an extension that is particularly suited for precise attitude determination. As opposed to current practice, our method does proper justice to the a priori given information. The nonlinear baseline constraint is fully integrated into the ambiguity objective function, thereby receiving a proper weighting in its minimization and providing guidance for the integer search. Different search strategies are developed to compute exact and approximate solutions of the nonlinear constrained ILS problem. Their applicability depends on the strength of the GNSS model and on the length of the baseline. Two of the presented search strategies, a global and a local one, are based on the use of an ellipsoidal search space. This has the advantage that standard methods can be applied. The global ellipsoidal search strategy is applicable to GNSS models of sufficient strength, while the local ellipsoidal search strategy is applicable to models for which the baseline lengths are not too small. We also develop search strategies for the most challenging case, namely when the curvature of the non-ellipsoidal ambiguity search space needs to be taken into account. Two such strategies are presented, an approximate one and a rigorous, somewhat more complex, one. The approximate one is applicable when the fixed baseline variance matrix is close to diagonal. Both methods make use of a search and shrink strategy. The rigorous solution is efficiently obtained by means of a search and shrink strategy that uses non quadratic, but easy-to-evaluate, bounding functions of the ambiguity objective function. The theory presented is generally valid and it is not restricted to any particular GNSS or combination of GNSSs. Its general applicability also applies to the measurement scenarios (e.g. single-epoch vs. multi-epoch, or single-frequency vs. multi-frequency). In particular it is applicable to the most challenging case of unaided, single frequency, single epoch GNSS attitude determination. The success rate performance of the different methods is also illustrated. Numéro de notice : A2010-569 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-010-0380-8 Date de publication en ligne : 02/04/2010 En ligne : https://doi.org/10.1007/s00190-010-0380-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30761 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2010071	SL	Revue	Centre de documentation	Revues en salle	Disponible