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Titre : Gravity field processing towards LL-SST satellite missions Type de document : Thèse/HDR Auteurs : Ilias Daras, Auteur ; Roland Pail, Directeur de thèse Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 2016 Collection : DGK - C, ISSN 0065-5325 num. 770 Importance : 153 p. ISBN/ISSN/EAN : 978-3-7696-5182-9 Note générale : bibliographie
PhD DissertationLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] accéléromètre
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] crénelage
[Termes IGN] filtrage du bruit
[Termes IGN] gravimétrie spatiale
[Termes IGN] interféromètre au laser
[Termes IGN] poursuite de satellite
[Termes IGN] résidu
[Termes IGN] satellite d'observation de la TerreRésumé : (auteur) This study focuses on important aspects concerning gravity field processing of future LL-SST [Low-Low Satellite-to-Satellite Tracking] satellite missions. Closed-loop simulations taking into account error models of new generation instrument technology are used to estimate the gravity field accuracy that future missions could provide. Limiting factors are identified, and methods for their treatment are developed. The contribution of all error sources to the error budget is analyzed. It is shown that gravity field processing with double precision may be a limiting factor for exploiting the nm-level accuracy of a laser interferometer. An enhanced numerical precision processing scheme is proposed instead, where double and quadruple precision is used in different parts of the processing chain. It is demonstrated that processing with enhanced precision can efficiently handle laser measurements and take full advantage of their accuracy, while keeping the computational times within reasonable levels. However, error sources of considerably larger impact are expected to affect future missions, with the accelerometer instrument noise and temporal aliasing effects being the most significant ones. The effect of time-correlated noise such as the one present in accelerometer measurements, can be efficiently handled by frequency dependent data weighting. Residual time series that contain the effect of system errors and propagated accelerometer and laser noise, is considered as a noise realization with stationary stochastic properties. The weight matrix is constructed from the auto-correlation functions of these residuals. Applying the weight matrix to a noise case considering all error sources leads to reduction of the error level over the complete spectral bandwidth. Co-estimation of empirical accelerations does not show the same efficiency in reducing the propagated noise with the applied processing strategy. Temporal aliasing effects are reduced essentially by adding a second pair of satellites at an inclined orbit. Compared to a GRACE-type near-polar pair, such a Bender-type constellation delivers solutions with major improvements in terms of de-aliasing potential and recovery performance. When the integrated effect of all geophysical processes is recovered, the maximum spatial resolution of 11-day solutions can be increased from 715 to 315 km half-wavelength. A further reduction of temporal aliasing errors is possible by co-parameterizing low resolution gravity fields at short time intervals, together with the higher resolution gravity field which is sampled at a longer time interval. One day was found to be the optimal sampling period for reducing the error levels in the solutions. A uniform sampling at the co-parameterized short periods, is a prerequisite for an efficient reduction of aliasing errors. High frequency atmospheric signals are captured by daily solutions to a large extent. Hence co-parameterization at daily basis results in significant reduction of aliasing caused by their under-sampling. This enables future gravity satellite missions to deliver the complete spectrum of Earth's geophysical processes. The corresponding by-products of daily gravity field solutions are expected to be very useful to atmospheric science and open doors to new fields of application. Note de contenu : 1. Introduction
1.1. Background
1.2. Motivation and objectives of this study
1.3. Outline
2. Earth's gravity field determination form satellite observations
2.1. Pertubing forces acting on a satellite
2.2. Geopotential and its functionals
2.3. Dedicated gravity satellite missions
2.4. Concepts for future satellite gravity missions
3. Description of the simulation environment for the gravity fields recovery
3.1. Outline of the simulation environment
3.2. Coordinate and time systems
3.3. Simulation if the satellite orbits
3.4. Functional model
3.5. Formulation of the NEQ system
3.6. Solution of the NEQ system
4. Design aspects and error budget of future dedicated gravity satellite missions
4.1. Orbit design
4.2. Satellite formation flights
4.3. Selected orbits for the simulations
4.4. Science and mission requirements
4.5. Noise models for the performance of the instruments
4.6. Error budget analysis
7. Treatment of temporal aliasing effects
7.1. Temporal aliasing for NGGLs
7.2. Co-parameterization of low spatial resolution gravity fiels solutions at higher frequencies
7.3. Retrieval content of NGGM gravity fiels solutions
8. ConclusionsNuméro de notice : 19791 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Note de thèse : PhD Dissertation : Geodesy : Stuttgart : 2016 DOI : sans En ligne : http://nbn-resolving.de/urn:nbn:de:bvb:91-diss-20160211-1279854-1-3 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85011
Titre : Probabilistic multi-person localisation and tracking Type de document : Thèse/HDR Auteurs : Tobias Klinger, Auteur ; Ingo Neumann, Directeur de thèse Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 2016 Collection : DGK - C, ISSN 0065-5325 num. 787 Importance : 125 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-5199-7 Note générale : bibliographie
PhD DissertationLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] analyse de sensibilité
[Termes IGN] analyse multicritère
[Termes IGN] classification
[Termes IGN] détection de piéton
[Termes IGN] géolocalisation
[Termes IGN] image isolée
[Termes IGN] modèle stochastique
[Termes IGN] objet mobile
[Termes IGN] piéton
[Termes IGN] poursuite de cible
[Termes IGN] programmation linéaire
[Termes IGN] séquence d'images
[Termes IGN] similitude
[Termes IGN] surveillanceRésumé : (auteur) This dissertation investigates the problem of localising multiple persons in image sequences, while, at the same time, establishing temporal correspondences between single-frame locations. The aim of this work is the improvement of the reliability and precision of the generated trajectories, which is addressed by the formulation and investigation of a joint probabilistic model for the recursive filtering of the estimated positions. The trajectories are estimated in a common 3D object coordinate system, which was previously almost exclusively done in 2D. Note de contenu : 1. Introduction
1.1. Motivation
1.2. Research objectives and contributions
1.3. Outline of the dissertation
2. Basics
2.1. Probabilistic modelling
2.2. Recursive Bayesian estimation
2.3. Gaussian Process Regression
3. Related work
3.1. Tracking approaches
3.2. Observations
3.3. Temporal modelling
3.4. Data association
3.5. Discussion
4. A new probabilistic approach for multi-person localisation and tracking
4.1. Problem statement via Dynamic Bayesian Network
4.2. Observations
4.3. Temporal model
4.4. data association
4.5. Recursive estimation
4.6. Discussion
5. Experiments
5.1. Datasets and evaluation criteria
5.2. Sensitivity study and training
5.3. Model validation by ablation of its components
5.4. Multi-person localisation and tracking evaluation
6. Discussion of the results
6.1. Method evaluation
6.2. Evaluation of the trajectories
7. Conclusions and future workNuméro de notice : 19793 Affiliation des auteurs : non IGN Thématique : IMAGERIE/INFORMATIQUE Nature : Thèse étrangère Note de thèse : PhD Dissertation : : Stuttgart : 2016 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85037 Documents numériques
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Titre : Korrektur stationsabhängiger Fehler bei GNSS Type de document : Thèse/HDR Auteurs : Andreas Knöpfler, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 2015 Collection : DGK - C, ISSN 0065-5325 num. 744 Importance : 177 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-5156-0 Note générale : bibliographie
akademisches Grades eines Doktor-Ingenieurs von der Fakultüt für Bauingenieur-, Geo- und Umweltwissenschaften des Karlsruher Instituts für TechnologieLangues : Allemand (ger) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] antenne GNSS
[Termes IGN] centre de phase
[Termes IGN] erreur systématique
[Termes IGN] étalonnage d'instrument
[Termes IGN] modèle d'erreur
[Termes IGN] positionnement ponctuel précis
[Termes IGN] positionnement statique
[Termes IGN] résidu
[Termes IGN] traitement de données GNSS
[Termes IGN] trajet multipleMots-clés libres : stacking map Index. décimale : 30.60 Géodésie spatiale Résumé : (auteur) Highly precise positioning techniques based on Global Navigation Satellite Systems (GNSS) have become a standard tool for numerous disciplines, benefitting from the continuous development of receiver equipment and the appearance of additional GNSS. In addition to the classical differential processing approach, the Precise Point Positioning (PPP) method is able to derive station coordinates with the same accuracy as a baseline setup, when sufficient observation time is available. The basis for PPP is the improved quality of external products for the GNSS data processing, for example the orbit and especially the satellite clock products of the International GNSS Service (IGS) and its analysis centers.
The increased usage of GNSS comes along with higher demands on accuracy. Therefore, the modelling of important error sources in GNSS is continuously upgraded. Intensive research led to a refinement of both the functional and the stochastic model in GNSS data processing in order to enable the correction of specific error components, for example the antenna behaviour or the tropospheric delay. Despite of the improvements in GNSS modelling, multipath effects still remain as a main error source in highly precise GNSS positioning. Within this work, stacking techniques are used to correct for multipath effects and further site dependent errors, for example residual errors in the calibration values of the receiving GNSS antenna. The method developed in this work is based on zero difference PPP residuals, which are accumulated over defined azimuth-elevation cells and over a fixed period of time (here: 10 d) and introduced as correction (so-called stacking maps) in a second PPP processing run. The main purpose of this approach aims for the improvement of data, recorded on continuously operating reference stations.
Within this work, two scenarios for the implementation of the corrections were investigated in detail: the combination of the stacking maps joined with the calibration information of the GNSS receiving antennas and in contrast to this approach the separate modelling of both aspects in a separate file. In order to check the effectivity of this method, the results (e.g., coordinates, residuals) before and after the introduction of the stacking maps were intensively analyzed. Within the second scenario (introduction of the correction in a separate file), the behaviour of the stacking maps over time was investigated by the analysis of so-called sliding stacking maps. Sliding stacking maps are generated as follows: calculation of a first stacking map from the residuals for example for day of year (DoY) 121 to 130 and introduction as correction for DoY 131, the next stacking map is computed from the residuals for DoY 122 to 131 and introduced for DoY 132 and so on. Especially sites with poor data quality show a significant improvement of the residual values after the implementation of stacked information. Furthermore, observations remain in the used data set, whereas they were eliminated in the processing without the introduction of stacking maps.
In addition, the necessity of expensive, site-dependent individual antenna calibration was checked. The focus was on the compensating level of the stacking approach with respect to unmodelled antenna effects based on the replacement of individual receiving antenna calibrations by type mean values of the IGS in combination with stacking maps. Therefore, data of selected sites were processed using both the existing individual antenna calibration sets and the IGS type mean values. In a second processing run, the calibration sets were introduced taking the corresponding stacking information into account. Differences in the phase center variations of the antennas can be corrected by the stacking maps. Discrepancies due to differences in the phase center offsets remain in the estimated site coordinates.Numéro de notice : 14920 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Note de thèse : PhD : Géodésie : Karlsruhes Institut für Technologie : 2015 DOI : 10.5445/KSP/1000045959 En ligne : https://doi.org/10.5445/KSP/1000045959 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76931 Ableitung von Bewegungsstrategien zur automatisierten, vollständigen Vermessung von Innerraumszenen auf autonom navigierender Plattform / Alexander Fietz (2012)
Titre : Ableitung von Bewegungsstrategien zur automatisierten, vollständigen Vermessung von Innerraumszenen auf autonom navigierender Plattform Titre original : [Détournement (ou dérivation) de stratégies de mouvement pour la mesure complète et automatisée de scènes spatiales intérieures sur la plate-forme de navigation autonome] Type de document : Thèse/HDR Auteurs : Alexander Fietz, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 2012 Collection : DGK - C Sous-collection : Dissertationen num. 685 Importance : 164 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-5097-6 Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Applications photogrammétriques
[Termes IGN] bloc photo
[Termes IGN] caméra numérique
[Termes IGN] compensation par faisceaux
[Termes IGN] données lidar
[Termes IGN] données localisées 2D
[Termes IGN] données localisées 3D
[Termes IGN] lasergrammétrie
[Termes IGN] photogrammétrie terrestre
[Termes IGN] plateforme
[Termes IGN] positionnement en intérieur
[Termes IGN] reconstruction 3D
[Termes IGN] robot
[Termes IGN] segment de droite
[Termes IGN] semis de points
[Termes IGN] système de numérisation mobile
[Termes IGN] tachéomètre électronique
[Termes IGN] varianceRésumé : (Auteur) A fundamental task of an autonomous mobile robot is the ability of self-localization in its environment respectively in a map of it, available to the robot. Many applications require a localization that is as precise as possible. Thereby, a decisive factor is the accuracy but also the completeness of the map. The generated map can usually be seen as a necessary side-product. When considered from a surveying point of view, it is brought more into focus. The question is to what extent the spatial robot data can fulfill certain mapping requirements in terms of accuracy and completeness in a detailed enough manner to be useful to human users. Precise models of indoor environments are very useful in both public and private sectors. But since their procurement involves a great deal of effort, an automatical generation of indoor models is desirable.
The following thesis should make a contribution to this and tries to compose the techniques that are necessary to deliver interior models at the push of a button. Therefore, a mobile measuring system was designed, that is able to carry out complete and precise measurements of indoor environments. The system was build up in two stages. A mobile platform is equipped with a low-cost laser scanner in the basic stage. This build-up allows a precise exploration of indoor scenes in 2D. In an expansion stage the installation of a digital camera leads to an additional 3D reconstruction based on photogrammetric techniques.
The accuracy and quality of robotic mapping is primarily dependent on the sensors that are used. The software process to register the collected data in a common coordinate frame and to create a holistic map of the environment has an additional influence. In the field of scanning systems scan matching techniques or probabilistic filter approaches are used. In the case of 3D surveying, a photogrammetric reconstruction can be done by an estimation of feature points, which are extracted from a photo block, within a bundle adjustment process. Results can be optimized, if requirements and restrictions of these techniques are regarded in the data acquisition process, when the robot proceeds the exploration. A crucial aspect is the spatial sensor placement at a certain point of time in this process. In the field of robotics, sensor placement is controlled by positioning strategies, which normally are of overriding importance to all other processes. The majority of known positioning strategies have the primary aim to optimize the efficiency of the exploration, so that every measurement provides as much new spatial information as possible. Requirements of the data registration technique are neglected in contrast. This thesis presents positioning strategies for scanning 2D measurements as well as photogrammetric 3D measurements, which try to maximize the accuracy of the collected spatial data. A scanning 2D measuring system, which is able to explore previously unknown indoor environments and generate precise floor plans is presented in the first part of this thesis. The system iteratively visits measurement poses defined by a positioning strategy. 2D point clouds, collected at various positions, are transformed into a common coordinate system by the use of a scan matching technique. The latter takes advantage of the characteristic manifestation of office environments and extracts planar segments from the measured point clouds. Minimizing the sum of perpendicular distances to these segments, points of a new scan are transformed into the existing coordinate system with high accuracy. Precision and robustness are improved through iterative parameter refinement. The measuring system uses a positioning strategy, which is based on the global assumption that the environment can be described as a collection of line segments. Since segment ends indicate data gaps, exploration is pushed until their observation is complete. All accessible measuring positions, represented in an occupancy grid, are evaluated in terms of their explorative benefit by the strategy using a cost function. Exploration is stopped as soon as every section is observed with a desired resolution.
The second part of this work presents a positioning strategy to enable the recording of photo blocks that are suitable for a photogrammetric reconstruction. In the run-up of data acquisition possible pose configurations are determined using accuracy estimation. The assumption of plain environments allows a limitation to a 2D search problem regarding the choice of possible camera poses, whereby the combinatorial variety is reduced. Initial information of pose estimation provides a 2D map, generated by the system structure that was presented in the first part of this work. For predefined sections of the environment, pseudo-random pose constellations are derived iteratively from the map and compared with each other using a cost function. The cost function helps to predict the variances resulting from a bundle adjustment. Therefore the functional model of the bundle adjustment has to be projected on the R2 in a way that a geodetic network consisting of direction measurements remains. The size and the shape of the resulting error ellipses allow conclusions and a comparative consideration regarding the quality of camera pose candidates.
An essential part of the work is the empirical analysis of the systems, to evaluate their performance and the quality of the resulting spatial data. Various experiments in real indoor environments show that developed measurement methods can be applied in practice. In different sets of experiments initial conditions are varied to find out their influence on the measurement process or the result. In order to achieve reliable results, reference models of the experimental environments were created by the use of a total station.
In the case of scanner measurements, experiments show that the developed system is able to explore and measure also complex interiors. An examination of the point clouds show that the achieved accuracy comes up with surveying demands. On this issue, the presented technique outplays conventional measuring equipment. However, additional modeling shows that mainly fine structures of the environment are displayed wrongly or are even lost completely. Also the 3D measuring strategy is demonstrably superior to existing techniques. The purely passive technique leads to sparse point clouds, not dense enough to derive detailed environment models with the corresponding software.Numéro de notice : 14621 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Thèse étrangère DOI : sans En ligne : https://www.ifp.uni-stuttgart.de/dokumente/Dissertationen/diss-fietz-c-685.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=62672 Attributierte Grammatiken zur Rekonstruktion und Interpretation von Fassaden / J. Schmidtwilken (2012)
Titre : Attributierte Grammatiken zur Rekonstruktion und Interpretation von Fassaden Titre original : [Grammaires attribuées pour la reconstruction et l'interprétation des façades] Type de document : Thèse/HDR Auteurs : J. Schmidtwilken, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 2012 Collection : DGK - C Sous-collection : Dissertationen num. 686 Importance : 169 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-5098-3 Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] façade
[Termes IGN] objet géographique complexe
[Termes IGN] reconstruction 3D du bâti
[Termes IGN] semis de pointsRésumé : (Auteur) The needs and benefits of highly detailed 3D city and building models is opposed to their expensive acquisition. Though the automatic derivation of simplified roof structures from aerial images or laser altimetry is mostly solved, only a few approaches for the automatic reconstruction of facade structures from terrestrial data were presented yet. Most of the existing work is on the interpretation of large, planar facades that are reduced to a regular arrangement of windows. Therefore, it lacks in both, the reconstruction of additional facade elements such as stairs or doors as well as methods for the interpretation of heterogeneous a,nd complex facades with protrusions, oriels and only a small number of windows.
This thesis deals with the interpretation of 3D point clouds that have been captured by terrestrial laser scanning of urban areas. The focus is on 3D point clouds of heterogeneous facades, that are characterized by their narrow width and by protrusions and oriels. The main contribution is the reconstruction and interpretation of facades by a parser that combines attribute grammars and robust estimators. Due to the generic attribute grammar the estimation of models with a previously unknown number of parameters is possible and the heterogeneity of the objects is thus considered.
The concept is distinguished by the heavily integration of prior knowledge. The geometric and the semantic model of facades are defined and transferred to the attributed grammar. Furthermore, the probability densities of the shape and position parameters of the considered facade parts are estimated and Incorporated in the attributed grammar. The corresponding a priori probabilities are essential for the presented robust estimator MOSAP and the parsing algorithm parseSd.
The relations between single parts of a facade are mapped to the attribute grammar. Therefore, the grammar represents the complex structures of facades and constitutes the foundation of the parsing algorithm. Beginning with the most common symbol parse3d iteratively applies production rules and, thus, generates hypothesis represented by derivation trees. Finally the most likely derivation tree is selected. Both, the selection of the symbol to be derived and the selection of the production rule to be applied base on the a priori probabilities and the densities that are estimated from the context information like the parameters of already reconstructed objects or subsets of the 3D point cloud. The interface between the grammar and the 3D point clouds is realized by the robust estimator MOSAP and guards. The latter determine the likelihood of a production rule and, therefore, provide a selection criterion.
The symbols of the grammar t.iat are geometrically defined by a small set of parameters axe reconstructed by a robust estimator. MOSAP (Model Based Sampling and Prediction) bases on the hypothesize-and-verify paradigm and is characterized by the model-based sampling strategy that takes advantage of the probability densities of the shape and position parameters of the objects to be reconstructed. Furthermore, MOSAP evaluates the hypothesis by the newly introduced goodness of prediction criterion.Numéro de notice : 14499 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Thèse étrangère Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=62665 Documents numériques
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