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Ableitung von Bewegungsstrategien zur automatisierten, vollständigen Vermessung von Innerraumszenen auf autonom navigierender Plattform / A. 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 : A. 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 descripteurs IGN] bloc photo
[Termes descripteurs IGN] chambre de prise de vue numérique
[Termes descripteurs IGN] compensation par faisceaux
[Termes descripteurs IGN] données lidar
[Termes descripteurs IGN] données localisées 2D
[Termes descripteurs IGN] données localisées 3D
[Termes descripteurs IGN] lasergrammétrie
[Termes descripteurs IGN] photogrammétrie terrestre
[Termes descripteurs IGN] plateforme
[Termes descripteurs IGN] positionnement en intérieur
[Termes descripteurs IGN] reconstruction 3D
[Termes descripteurs IGN] robot
[Termes descripteurs IGN] segment de droite
[Termes descripteurs IGN] système de numérisation mobile
[Termes descripteurs IGN] tachéomètre électronique
[Termes descripteurs IGN] variance
Résumé : (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 Thématique : IMAGERIE Nature : Thèse étrangère Permalink :
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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 descripteurs IGN] données lidar
[Termes descripteurs IGN] données localisées 3D
[Termes descripteurs IGN] façade
[Termes descripteurs IGN] objet géographique complexe
[Termes descripteurs IGN] reconstruction 3D du bâti
[Termes descripteurs IGN] semis de points
Résumé : (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 Thématique : IMAGERIE Nature : Thèse étrangère Permalink :
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Effects on the geodetic-VLBI observables due to polarization leakage in the receivers / A. Roy (2012)
Titre : Effects on the geodetic-VLBI observables due to polarization leakage in the receivers Type de document : Thèse/HDR Auteurs : A. Roy, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 2012 Collection : DGK - C Sous-collection : Dissertationen num. 681 Importance : 160 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-5093-8 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes descripteurs IGN] données ITGB
[Termes descripteurs IGN] interférométrie à très grande base
[Termes descripteurs IGN] polarisation
[Termes descripteurs IGN] récepteur
Résumé : (Auteur) Geodetic VLBI delivers baseline length and Earth orientation parameter measurements, which offer the most viable and precise way to study Earth crustal and core dynamics and to support space navigation. The precision of these geodetic and astrometric measurements is degraded by instrumental errors of which polarization leakage is one of the larger. Its effect can be corrected in the data provided one knows the leakage characteristics of the stations. In this work I introduce the concept of polarization, why it needs to be considered in the geodetic analysis and present a VLBI experiment that measured the polarization leakage at 16 geodetic and VLBA stations over the frequency range 8212.99 MHz to 8932.99 MHz and 2225.99 MHz to 2365.99 MHz. I describe resulting polarization leakage measurements and the algorithm that was implemented to correct for their effect on the geodetic delay measurables. I applied the correction for polarization leakage to a routine geodetic VLBI experiment and check for the resulting improvement. Prom the measured leakage terms, one would expect polarization leakage to affect the group delay measurements by 0.5 ps to 7 ps, depending on the stations involved in the baseline. This proved to be below the statistical noise in a single VLBI experiment and so the improvement from the correction could not be detected. Polarization leakage was found, unexpectedly, not the dominant source of non-closing errors. Numéro de notice : 14618 Thématique : POSITIONNEMENT Nature : Thèse étrangère Permalink :
14618_dgk-c-681_roy.pdfAdobe Acrobat PDF
Ein modulares Simulationskonzept zur Evaluierung von Positionssensoren sowie Filter- und Regelalgorithmen am Beispiel des automatisierten Strassenbaus / A. Beetz (2012)
Titre : Ein modulares Simulationskonzept zur Evaluierung von Positionssensoren sowie Filter- und Regelalgorithmen am Beispiel des automatisierten Strassenbaus Titre original : [Une méthode de simulation modulaire pour l'évaluation de détecteurs de position ainsi que d'algorithmes de filtre et de règle avec l'exemple de la construction automatisée de routes] Type de document : Thèse/HDR Auteurs : A. Beetz, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 2012 Collection : DGK - C Sous-collection : Dissertationen num. 688 Importance : 175 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-5100-3 Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes descripteurs IGN] détecteur
[Termes descripteurs IGN] engin de travaux publics
[Termes descripteurs IGN] filtre
[Termes descripteurs IGN] guidage de véhicules
[Termes descripteurs IGN] positionnement cinématique
[Termes descripteurs IGN] test de performance
Résumé : (Auteur) In recent years, great progress has been made in the field of automated road construction, so that automated construction machines are already widely used on large highway construction sites. In these machines automated height control of the tools is mainly used. A completely automated control of the position and height of the vehicle and the tool is only realized for slow-moving construction machines such as asphalt pavers and slip form pavers. The design of such systems is usually carried out individually for each machine, for which the combination of sensors, filters and control algorithms is of prime importance. Usually, the design must be effected again for each type of construction machine. Previous simulations for the implementation of the software on the machine computer are usually realized on software side. An intermediate step is missing in which sensor components or filter algorithms can be tested individually in the laboratory without being affected by outside influences such as of the ground or other environmental influences. The development of a three-step approach in this thesis closes this gap by developing an additional hardware-in-the-loop simulator. For the hardware-in-the-loop simulator remote-controlled vehicles in a scale of 1:14 are used which are able to reflect a realistic kinematic behavior. Simulations can be performed due to the interconnection of different sensors, software, and the remote-controlled models. Thereby new sensors and algorithms can be optimized in laboratory with respect to their implementation.
For the realization of the simulator, a geometric description of widely spread kinematic vehicle models is set up. Furthermore, an exemplary geometric description is shown for three characteristic tools of construction machines. These tools are the plate of a bulldozer, the plate of a motor grader and the screed of an asphalt paver. A local sensitivity analysis is carried out on the basis of two of these geometrical tool models, which determines the influence of various sensors on the achievable position accuracy of the tools.
For a better understanding of the terms of systems theory and control engineering, a brief introduction is given to these topics. In this introduction, the focus is laid on controllers used for lateral control of the vehicle models on a predetermined trajectory in the simulator. The controllers used consist of various combinations of the PID controller and are thus based on a non-model based approach. The root mean square (RMS = Root Mean Square) is adopted for the description of the control quality. The RMS is calculated with lateral deviations of the vehicle to a desired trajectory during the lateral control. It will be applied to evaluate the used sensors, the controllers and filter algorithms in the control loop. Before using the controllers in the simulator system, they will be evaluated by means of software simulations.
Three robotic total stations are used for the positioning of the controlled vehicles in the simulator. They will be analyzed as to their achievable accuracy in order to determinate the control quality. In this case also a laser tracker is used as a position reference, so that it is possible to make a separation of the control quality from the accuracy of the measurement.
The vehicles implemented in the simulator are a caterpillar and a truck model. With these remote-controlled models it is possible to investigate a large range of vehicle models found on construction sites. In order to determine the steering parameters for a computer-aided control system, an automated calibration method is presented for these models. The simulator is used for testing the implemented vehicle models and also to compare two variants of Kalman filters with respect to improving the control quality. Within the test series, a control quality of 2-4 mm at a speed range of 10 - 30 cm/s could be achieved.
Numéro de notice : 14624 Thématique : POSITIONNEMENT Nature : Thèse étrangère Permalink :
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Entwicklung eines Kalman-Filters zur Bestimmung kurzzeitiger Variationen des Erdschwerefeldes aus daten der Satellitenmission GRACE / E. Kurtenbach (2012)
Titre : Entwicklung eines Kalman-Filters zur Bestimmung kurzzeitiger Variationen des Erdschwerefeldes aus daten der Satellitenmission GRACE Titre original : Development of a Kalman filter to derive short-term variations of the Earth's gravity field from GRACE data Type de document : Thèse/HDR Auteurs : E. Kurtenbach, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 2012 Collection : DGK - C Sous-collection : Dissertationen num. 683 Importance : 120 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-5095-2 Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes descripteurs IGN] champ de pesanteur terrestre
[Termes descripteurs IGN] corrélation automatique de points homologues
[Termes descripteurs IGN] crénelage
[Termes descripteurs IGN] données GRACE
[Termes descripteurs IGN] filtre de Kalman
[Termes descripteurs IGN] série temporelle
[Termes descripteurs IGN] variation temporelle
Résumé : (Auteur) The gravitational field and its temporal variations represent an important observable for the monitoring of the Earth's system. The satellite mission GRACE (Gravity Recovery And Climate Experiment) is, for the first time, able to measure gravity field variations with homogeneous global coverage. Nevertheless, the predicted GRACE accuracy has not been reached yet, partly due to the insufficient representation of the temporal variations in terms of monthly mean fields. In this thesis, an approach is presented which allows the calculation of daily GRACE solutions with the goal of modeling short-term gravity field variations. This time series can on the one hand be used to improve the knowledge of the underlying geophysical processes. On the other hand the daily GRACE solutions can also be used to improve the monthly mean fields. Increasing the temporal resolution is accompanied by a loss of accuracy due to insufficient data coverage. Therefore, additional information in terms of temporal and spatial correlations of the expected gravity signal is introduced into the analysis process. The combination of the GRACE observations and the correlation patterns is then performed within a Kalman filter framework. In a simulation study, the performance of the approach at hand is investigated and, in a second step, applied to real GRACE LIB data. Comparisons to independent data sets, i.e. vertical displacements of GPS stations and ocean bottom pressure time series, reveal that the daily GRACE time series contains geophysically interpretable signal. Furthermore, the daily GRACE time series can be used to significantly reduce the effects of temporal aliasing in the processing of monthly mean gravity field solutions. Numéro de notice : 14619 Thématique : POSITIONNEMENT Nature : Thèse étrangère Permalink :
14619_dgk-c-683_kurtenbach.pdfAdobe Acrobat PDF
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