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Parameterschätzung für unvollständige funktionale Modelle in der Geodäsie / S. Petrovic (2003)
Titre : Parameterschätzung für unvollständige funktionale Modelle in der Geodäsie Titre original : [Estimation des paramètres pour un modèle fonctionnel incomplet en géodésie] Type de document : Thèse/HDR Auteurs : S. Petrovic, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 2003 Collection : DGK - C Sous-collection : Dissertationen num. 563 Importance : 61 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-5002-0 Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] corrélation
[Termes IGN] erreur systématique
[Termes IGN] estimation statistique
[Termes IGN] méthode des moindres carrés
[Termes IGN] modèle mathématiqueIndex. décimale : 30.10 Systèmes de référence et réseaux géodésiques Note de contenu : 1) Motivation
1.1 Unvollständige Modelle
1.2 Behandlung systematischer Fehler in der Literatur
1.3 Zum Nachweis der Existenz systematischer Einflüsse in den Daten
1.4 Zur Ausgleichung unvollständiger Modelle
2) Kurze Darstellung der Ausgleichung nach maximaler Korrelation
2.1 Allgemeine Bemerkungen
2.2 Korrelationskoeffizient
2.3 Ausgleichung nach maximaler Korrelation
2.3.1 Definition
2.3.2 Verallgemeinerung auf gewichtete und korrelierte Beobachtungen
2.3.3 Mehrdeutigkeit der Lösung
2.3.4 Lösung des Ausgleichungsproblems nach maximaler Korrelation
2.3.5 Lineare Probleme
2.3.6 Beziehung zur Methode der kleinsten Quadrate
3) Anwendung der Ausgleichung nach maximaler Korrelation bei unvollständigen Modellen
3.1 Allgemeine Strategie
3.2 Residuenanalyse
3.2.1 Aufstellen zusätzlicher Bedingungen
3.2.2 Eindimensionaler Fall
4) Synthetische Beispiele
4.1 Beispiel ohne zufällige Fehler
4.2 Einführung zufälliger Fehler
4.3 Einfluß von Datenlücken
4.4 Nichteindeutige Aufgabenstellungen
5) SchlußbetrachtungNuméro de notice : 13190 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54905 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 13190-02 30.10 Livre Centre de documentation Géodésie Disponible 13190-01 30.10 Livre Centre de documentation Géodésie Disponible Schätzung von Vegetationsparametern aus multispektralen Fernerkundungsdaten / F. Kurz (2003)
Titre : Schätzung von Vegetationsparametern aus multispektralen Fernerkundungsdaten Titre original : [Estimation des paramètres de végétation à partir de données de télédétection multi bandes] Type de document : Thèse/HDR Auteurs : F. Kurz, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 2003 Collection : DGK - C Sous-collection : Dissertationen num. 569 Importance : 101 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-5008-2 Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] agriculture de précision
[Termes IGN] blé (céréale)
[Termes IGN] chlorophylle
[Termes IGN] DEADALUS
[Termes IGN] données de terrain
[Termes IGN] hétérogénéité
[Termes IGN] image DEADALUS
[Termes IGN] Leaf Area Index
[Termes IGN] matière organique
[Termes IGN] méthode robuste
[Termes IGN] modèle de transfert radiatif
[Termes IGN] programmation linéaireRésumé : (Auteur) In this thesis, a method to estimate vegetation parameters from multispectral remote sensing data using physical radiative transfer models and a small amount of ground-truth data is proposed. During two years this method has been exemplarily validated for different winter wheat fields imaged by a Daedalus ATM multispectral scanner. The focus lies on the variations of vegetation parameters within single fields. These variations allow to derive information about soil heterogeneities, which are important parameters for precision farming applications. For the estimation of vegetation parameters, physical radiative transfer models are combined with a linear empirical model and inverted with numerical optimisation methods. Ground-truth measurements are employed to reduce errors by a linear empirical fitting of the applied physical models. Results of model inversions with synthetic and real datasets show, that four vegetation parameters, leaf area index, chlorophyll content, specific dry matter, and specific water content are estimable assuming the given configuration. The strength of this method lies on the comprehensive and robust modelling, which assures reliable estimation of several vegetation parameters with a minimum number of ground-truth measurements. The accuracies of the estimated parameters are comparable with the quality of the ground-truth measurements. Numéro de notice : 13200 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Thèse étrangère Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54910 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 13200-01 35.41 Livre Centre de documentation Télédétection Disponible 13200-02 35.41 Livre Centre de documentation Télédétection Disponible Zur Automation berührungsloser 3D-Objekterfassung im Nahbereich / M. Hovenbitzer (2003)
Titre : Zur Automation berührungsloser 3D-Objekterfassung im Nahbereich Titre original : [L'automatisation de la saisie d'objet 3D à distance] Type de document : Thèse/HDR Auteurs : M. Hovenbitzer, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 2003 Collection : DGK - C Sous-collection : Dissertationen num. 556 Importance : 82 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-9595-3 Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Photogrammétrie terrestre
[Termes IGN] analyse comparative
[Termes IGN] détecteur à transfert de charge
[Termes IGN] données localisées 3D
[Termes IGN] étalonnage d'instrument
[Termes IGN] instrument de mesure
[Termes IGN] lasergrammétrie
[Termes IGN] photogrammétrie architecturale
[Termes IGN] photogrammétrie métrologique
[Termes IGN] primitive géométrique
[Termes IGN] primitive volumique
[Termes IGN] semis de points
[Termes IGN] tachéomètre électronique
[Termes IGN] télémétrie laser terrestreIndex. décimale : 33.70 Photogrammétrie terrestre Résumé : (Auteur) This thesis describes the realization and the calibration of two measurement systems, which are designed for measuring contactless three dimensional object points in close range. A well adapted way of data processing is presented, which shows the reduction from a large amount of object points to geometric parameters of object surfaces. First the possible applications for such systems are shown. The spectrum ranges from the interior scanning for facility management systems over documentations of archaeological excavations to virtual representations of buildings for purposes of the real estatetrade. Afterwards the existing up to date systems for measuring three dimensional coordinates in close range are described.
The two developed measuring systems are described in detail. First the system Hybmess is introduced. The system is based on a standard motorized tacheometer. An additional CCDLinecamera is attached to the tacheometer below the telescope. The tacheometer is controlled by a computer to allow automatic positioning of the tacheometer and thus the camera. A projection unit is also mounted on the tacheometer. Structured light patterns are used to determine the object coordinates by intersection. The necessary Graycode patterns are projected by a laser beam deflected by a rotating prism. The interpretation of all projected patterns leads to a binary code for the last and most important pattern. This binary code contains the angle information which is necessary for calculating the intersection.
The second measuring system MLMS determines the coordinates of surface points by reflectorless distance measurement. The base sensor of the measuring system is the unit LMS 200 of the SICK company. This sensor is able to measure fanshaped distances with an apex angle of 180'. The sensor measures with the time of flight principle. A motorized rotation stage turns the base sensor around the vertical axis, so that a three dimensional scanning of the object is possible.
The processing of the measured data starts with the visualization of the scatterplot and results in a specification of the geometric parameters of the object. Two forms of visualization have been developed, which were well adapted to the measuring systems. The first form is the winding off visualization. Corresponding to the angle grid of the measurement system a picture is calculated, in which the local minima and maxima of the distances are marked with white dots. The second form of visualization is the perspective one. The gray value of the pixel depends on the distance between the central point and the object points. Because of the great amount of object points, the shapes of the object have to be extracted from the point cloud. For automatic respectively semiautomatic extraction of plains, spheres and cylinders algorithms have been developed. The intersection of these geometric shapes are corners or edges of the object. For scanning larger objects the combination of several instrument positions is necessary. The identical points can be the centers of measured spheres or the intersections of three measured plains. Mostly for the documentation of the object additional digital images are taken or the measurement system produces a digital image during the process of measuring. This additional information can be used for texturemapping the CADmodel of the object, or for measuring hidden objects or small details. The accuracy and precision of the new measuring systems is studied on some selected geometric objects. The scanning of interiors is an example for the presented way to combine several instrument positions.Numéro de notice : 13160 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Thèse étrangère Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54897 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 13160-01 33.70 Livre Centre de documentation Photogrammétrie - Lasergrammétrie Disponible Zur Bestimmung der GPS-Phasenmehrdeutigkeiten in großräumigen Netzen / K. Wienholz (2003)
Titre : Zur Bestimmung der GPS-Phasenmehrdeutigkeiten in großräumigen Netzen Titre original : [Vers la résolution des ambiguïtés de phase GPS dans les réseaux à grande échelle] Type de document : Thèse/HDR Auteurs : K. Wienholz, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 2003 Collection : DGK - C Sous-collection : Dissertationen num. 566 Importance : 102 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-5005-1 Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] ambiguïté entière
[Termes IGN] ligne de base
[Termes IGN] logiciel de post-traitement GPS
[Termes IGN] mesurage de phase
[Termes IGN] modèle mathématique
[Termes IGN] phase GPS
[Termes IGN] propagation ionosphérique
[Termes IGN] résolution d'ambiguïté
[Termes IGN] traitement de données GNSSIndex. décimale : 30.61 Systèmes de Positionnement par Satellites du GNSS Résumé : (Auteur) The development and the results of the TUB method are presented in this paper. This special method serves in resolving GPS phase ambiguities in small-range and large-range networks. It is characterized by taking into account the correlates as quality criteria, thus enabling an assessment of the calculated ambiguities. First of all : by simulating an example to mediate the adjustment of conditions between unknown quantities it can be shown that every incorrect condition exerts a major constraint on the adjustment system. This constraint is reflected by the pertaining Lagrange factors (or correlates), the value of which increases rapidly in line with the magnitude of error in the equation of condition. This knowledge can be used in the TUB method to investigate various parameters. However, in this paper the emphasis is on the investigation of ambiguities.
The TUB method is based on a special parameterization of the observation equations so that several unknown parameters are combined in one newly established time-dependent auxiliary parameter and in one timeindependent auxiliary parameter. By reduction of the unknown parameters a stable equation system is brought about which can be solved without resulting in differences and linear combinations. The direct analysis of original phase observations prevents the error-propagation of accidental errors and hence an artificial increase in phase noise. Therefore the confidence intervals, characterized by integer numbers, can be kept rather small. In finding these integer numbers the time-dependent auxiliary parameters must first be separated in different ways, depending on the lengths of the base lines, from the ionospheric refraction. Then the ambiguities in the form of double differences, related to a base satellite and a base station (or in the form of L1/L2 ambiguity pairs), can be solved in an iterative process. As a controlling device equations of condition are formed with the help of L1/L2 ambiguity pairs and inserted in the adjustment process. A subsequent analysis of the correlates gives information about the qualities of the ambiguities found.
To begin with the potential of the TUB method is tested by means of a data set with base line lengths ranging from 13 to 48 km. By analyzing the correlates incorrect double difference ambiguities can be identified and among several integer numbers the correct one is filtered out. In two further nets with base line lengths from 26 to 106 km the influences of various more or less accurate orbits on the parameters of the observation equations are investigated. In the aforementioned examples a resolution of the ambiguities is possible at a success rate of 100 percent while an observation time of about two hours is sufficient. When terrain points are between 700 and 1000 km apart the model shows consider-able inaccuracies. The evaluation of data stemming from various IGS stations evidences that in about 20 percent of all ambiguities integer numbers cannot be found. In these cases the confidence intervals either do not provide any integer number or too many of them. In the latter case there are, instead of a single one, several LI/L2 ambiguity pairs that do not differ very much from one another. When these ambiguity pairs are inserted in the equation system the values of the correlates do not differ very much either. For the time being no satisfactory results can be achieved for base lines ranging between 1000 and 2000 km.
The analysis of the correlates proves to be a useful tool in evaluating the quality of ambiguities. The correlates with the highest values occur when incorrect ambiguities exert major constraints on the equations of condition. In these cases errors can be detected, e.g., those arising from the use of broad-cast ephemerides. When several integer numbers are found in the confidence intervals the values of the correlates suggest values matching the normal equation system. Considerable interdependencies of the equations of condition are evident. Consequently there is an increase in the values that are linked to an incorrect condition via satellite and station. Therefore the correlations between the Lagrange factors should be investigated more closely. It is useful to determine the ambiguities of a data set by observation times of different lengths. By comparing the double difference ambiguities calculated from these solutions an additional examination of the results is made possible. Particularly when base lines of more than 1000 km are used it turns out that with data resulting from shorter observation times integer numbers can be calculated that would either not result at all or only inaccurately from longer measurements. The use of correlates as indicators for incorrect conditions is not only suitable for evaluating ambiguities in GPS analysis. Moreover, all parameters that can be formulated in appropriate conditions may be examined in any case of problems regarding the analysis of data.Numéro de notice : 13191 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54906 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 13191-02 30.61 Livre Centre de documentation Géodésie Disponible 13191-01 30.61 Livre Centre de documentation Géodésie Disponible Zur Höhensystemumstellung und Geoidberechnung in Bayern / C. Gerlach (2003)
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 altimétriqueIndex. 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 Réservation
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