Catalogue en ligne IGN

Zur Höhensystemumstellung und Geoidberechnung in Bayern / C. Gerlach (2003)

Public

Titre :	Zur Höhensystemumstellung und Geoidberechnung in Bayern
Titre original :	[Sur le changement de système d'altitudes et l'estimation du géoïde en Bavière]
Type de document :	Thèse/HDR
Auteurs :	C. Gerlach, Auteur
Editeur :	Munich : Bayerische Akademie der Wissenschaften
Année de publication :	2003
Collection :	DGK - C
Sous-collection :	Dissertationen num. 571
Importance :	129 p.
Format :	21 x 30 cm
ISBN/ISSN/EAN :	978-3-7696-5010-5
Note générale :	Bibliographie
Langues :	Allemand (ger)
Descripteur :	[Vedettes matières IGN] Géodésie physique [Termes IGN] altitude normale [Termes IGN] Bavière (Allemagne) [Termes IGN] covariance [Termes IGN] formule de Stokes [Termes IGN] géoïde local [Termes IGN] nivellement par GPS [Termes IGN] précision décimétrique [Termes IGN] problème des valeurs limites [Termes IGN] réseau de premier ordre [Termes IGN] système de référence altimétrique
Index. décimale :	30.41 Géoïde
Résumé :	(Auteur) Topographic heights are determined for various purposes and using different measurement techniques. This work gives a contribution to an accurate national height system for the federal state of Bavaria, Germany. One aspect is the determination of physical heights by means of geometric levelling combined with gravity measurements. The other aspect is to derive an accurate geoid in order to make use of the efficient method of levelling by GPS. Of course the definitions of the heights must be consistent with the used geoid. For both quantities (heights and geoid) there are different definitions and the differences between those cannot be neglected when in comes to the cm-level. For historic reasons, the former West-German national height system was computed in normal- orthometric heights and connected to the tide gauge Amsterdam. In the former German Democratic Republic normal heights were introduced, connected to a tide gauge in the Baltic sea. Thus, the reunification of Germany resulted in an inhomogeneous height system. The working group of the federal surveying authorities decided to set up a new consistent system, based on normal heights and connected to the level of Amsterdam. The first order network was computed in one step for the whole of Germany. It is the task of each federal state to compute the lower order networks for its own area. The first part of this work deals with height computations in the area of Bavaria. Transformation algorithms from the old spheroidal heights into normal heights are investigated under the precondition, that the use of the original measurement records should be avoided because not all of them are available in digital form. It is shown that in most parts of Bavaria a relatively simple procedure can be used, while in mountainous regions, like the Alps, gravity interpolation becomes the critical point. The accuracy requirements can still be met by using Bouguer anomalies (including topographic reductions) or by a proper distribution of data and interpolation points. The quality descriptions are based on a comprehensive error budget of all relevant error sources and make use of empirical covariance functions. As the new height system will be given in normal heights, the proper geoid is the quasi-geoid, based on the theory of Molodensky. The second part of this work deals with the computation of an accurate quasi-geoid in Bavaria. It is based on a combination of the global potential model EGM96 and terrestrial gravity anomalies within a 4° cap around Bavaria. A high resolution digital terrain model with a grid spacing of 50 m is used in Bavaria to compute topographic reductions. Molodensky's series is computed up to third order and different kinds of modifications of Stokes' function are tested. Comparison to GPS/Ievelling heights shows, that the best results are achieved using the original Stokes-kernel. Still there are long and medium wavelength errors of some decimeters in all solutions. This holds true for the European quasi-geoid EGG97, too. Error simulations indicate that those are due to errors in the global potential model. In order to allow the use of the derived quasi-geoid for the determination of physical heights, it is fitted to a set of GPS/Ievelling points. This way an accuracy of 2-3 cm is achieved, which is at the accuracy level of geodetic GPS measurements.
Numéro de notice :	13201
Affiliation des auteurs :	non IGN
Thématique :	POSITIONNEMENT
Nature :	Thèse étrangère
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=54911

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
13201-01	30.41	Livre	Centre de documentation	Géodésie	Disponible
13201-02	30.41	Livre	Centre de documentation	Géodésie	Disponible

IGN

Centre de documentation
scientifique

Accueil

Sélection de la langue

Adresse

Se connecter

Actualité

L'actu ! Horaires du CDOS

Informations pratiques

Exemplaires(2)

IGN / ENSG

L'IGN a pour vocation

Accès directs

2014 -2024 IGN

IGN

Centre de documentationscientifique

Accueil

Sélection de la langue

Adresse

Se connecter

Actualité

L'actu ! Horaires du CDOS

Informations pratiques

Exemplaires(2)

IGN / ENSG

L'IGN a pour vocation

Accès directs

2014 -2024 IGN

Centre de documentation
scientifique