Between the fourth and the seventh centuries CE, Christian patrons erected thousands of churches, chapels, and monasteries in cities and villages across the Mediterranean, decorating the apses, walls and floors of many of these structures with figural and geometric mosaics. These late antique Christian mosaics have been studied for their iconography, their Graeco-Roman components, and as evidence for the religious beliefs of newly-Christian patrons. However, art historians largely have ignored the ways that texts, inscribed within the visual field and composed of the same mosaic material, functioned as images in Christian spaces. For the first time, this thesis assembles the foundations of a comprehensive catalogue of early Christian mosaic inscriptions, places them back into the physical spaces in which they were meant to be read, and analyzes how these texts functioned both verbally and visually for the late antique reader/viewer, against the backdrop of Graeco-Roman traditions. I first examine the ekphrastic components of Christian inscriptions and look more closely at the different ways in which texts work with and against images and spaces, encouraging the viewer to react physically and mentally. Second, I study the language of light used by the inscriptions, and argue that this language linked text to the material of mosaic and enabled patrons to make complex statements about their cultural erudition and religious affiliation. Third, I investigate the functions and visual forms of short tituli which label scenes or name figures to simplify, authenticate or transform static images into narratives in motion. Finally, I turn to the frames of the inscriptions and contend that different forms conveyed powerful visual arguments. By writing these texts back into their mosaics, this thesis argues that texts and images were inseparable in the period, and that text written into images performed and played in more complex ways than has been previously thought.

This thesis is an overview of the historical context in which the church of Christ the Redeemer (Sant'Apollinare Nuovo) in Ravenna, Italy, was erected. It explores the forces responsible for shaping the church at the time of its construction and decoration in the sixth century. The basilica had gained popularity of usage as a model for the Christian Church in the West by this time. This thesis further explores the conclusions put forth by scholars that the basilica was the forum in which the transition of architectural imperial symbolism from the pagan empire to the new Christian Church took place, that the Church adopted the court ceremony of the emperor for its liturgy, and that the symbolism previously associated with the emperor was transferred to Christ resulting in the identification of the basilica as the throne hall of Christ. A study of the mosaics adorning the nave walls describes the significance of their origins and meaning.

This thesis proposes a solution to the problem of estimating the motion of an Unmanned Underwater Vehicle (UUV). Our approach is based on the integration of the incremental measurements which are provided by a vision system. When the vehicle is close to the underwater terrain, it constructs a visual map (so called "mosaic") of the area where the mission takes place while, at the same time, it localizes itself on this map, following the Concurrent Mapping and Localization strategy. The proposed methodology to achieve this goal is based on a feature-based mosaicking algorithm. A down-looking camera is attached to the underwater vehicle. As the vehicle moves, a sequence of images of the sea-floor is acquired by the camera. For every image of the sequence, a set of characteristic features is detected by means of a corner detector. Then, their correspondences are found in the next image of the sequence. Solving the correspondence problem in an accurate and reliable way is a difficult task in computer vision. We consider different alternatives to solve this problem by introducing a detailed analysis of the textural characteristics of the image. This is done in two phases: first comparing different texture operators individually, and next selecting those that best characterize the point/matching pair and using them together to obtain a more robust characterization. Various alternatives are also studied to merge the information provided by the individual texture operators. Finally, the best approach in terms of robustness and efficiency is proposed.After the correspondences have been solved, for every pair of consecutive images we obtain a list of image features in the first image and their matchings in the next frame. Our aim is now to recover the apparent motion of the camera from these features. Although an accurate texture analysis is devoted to the matching pro-cedure, some false matches (known as outliers) could still appear among the right correspon-dences. For this reason, a robust estimation technique is used to estimate the planar transformation (homography) which explains the dominant motion of the image. Next, this homography is used to warp the processed image to the common mosaic frame, constructing a composite image formed by every frame of the sequence. With the aim of estimating the position of the vehicle as the mosaic is being constructed, the 3D motion of the vehicle can be computed from the measurements obtained by a sonar altimeter and the incremental motion computed from the homography.Unfortunately, as the mosaic increases in size, image local alignment errors increase the inaccuracies associated to the position of the vehicle. Occasionally, the trajectory described by the vehicle may cross over itself. In this situation new information is available, and the system can readjust the position estimates. Our proposal consists not only in localizing the vehicle, but also in readjusting the trajectory described by the vehicle when crossover information is obtained. This is achieved by implementing an Augmented State Kalman Filter (ASKF). Kalman filtering appears as an adequate framework to deal with position estimates and their associated covariances.Finally, some experimental results are shown. A laboratory setup has been used to analyze and evaluate the accuracy of the mosaicking system. This setup enables a quantitative measurement of the accumulated errors of the mosaics created in the lab. Then, the results obtained from real sea trials using the URIS underwater vehicle are shown.

Habilitationsschrift--Freiburg im Breisgau, 1968. / Includes indexes. Includes bibliographical references (p. 7-18).

Habilitationsschrift--Freiburg im Breisgau, 1968. / Includes indexes. Includes bibliographical references (p. 7-18).

Réduire la vulnérabilité et accroître la résilience des sociétés d'aujourd'hui aux fortes précipitations et inondations exige de mieux caractériser leur très forte variabilité spatio-temporelle observable sur une grande gamme d'échelle. Nous mettons donc en valeur tout au long de cette thèse l'intérêt méthodologique d'une approche multifractale comme étant la plus appropriée pour analyser et simuler cette variabilité. Cette thèse aborde tout d'abord le problème de la qualité des données, qui dépend étroitement de la résolution temporelle effective de la mesure, et son influence sur l'analyse multifractale et la détermination de lois d'échelle des processus de précipitations. Nous en soulignons les conséquences pour l'hydrologie opérationnelle. Nous présentons la procédure SERQUAL qui permet de quantifier cette qualité et de sélectionner les périodes correspondant aux critères de qualité requise. Un résultat surprenant est que les longues chronologies de pluie ont souvent une résolution effective horaire et rarement de 5 minutes comme annoncée. Ensuite, cette thèse se penche sur les données sélectionnées pour caractériser la structure temporelle et le comportement extrême de la pluie. Nous analysons les sources d'incertitudes dans les méthodes multifractales « classiques » d'estimation des paramètres et nous en déduisons des améliorations pour tenir compte, par exemple, de la taille finie des échantillons et des limites de la dynamique des capteurs. Ces améliorations sont utilisées pour obtenir les caractéristiques multifractales de la pluie à haute résolution de 5 minutes pour plusieurs départements de la France (à savoir, les départements 38, 78, 83 et 94) et pour aborder la question de l'évolution des précipitations durant les dernières décennies dans le cadre du changement climatique. Cette étude est confortée par l'analyse de mosaïques radars concernant trois événements majeurs en région parisienne. Enfin, cette thèse met en évidence une autre application des méthodes développées, à savoir l'hydrologie karstique. Nous discutons des caractéristiques multifractales des processus de précipitation et de débit à différentes résolutions dans deux bassins versant karstiques au sud de la France. Nous analysons, en utilisant les mesures journalière, 30 minutes et 3 minutes, la relation pluie-débit dans le cadre multifractal. Ceci est une étape majeure dans la direction d'une définition d'un modèle multi-échelle pluie-débit du fonctionnement des bassins versants karstiques / To reduce vulnerability and to increase resilience of nowadays societies to heavy precipitations and floods require better understanding of their very strong spatio-temporal variability observable over a wide range of scales. Therefore, throughout this thesis we highlight the methodological interest of a multifractal approach as being most appropriate to analyze and to simulate such the variability. This thesis first discusses the problem of data quality, which strongly depends on the effective temporal resolution of the measurements, and its influence on multifractal analysis determining the scaling laws of precipitation processes. We emphasize the consequences for operational hydrology. We present the SERQUAL procedure that allows to quantify the data quality and to select periods corresponding to the required quality criteria. A surprising result is that long chronological series of rainfall often have an effective hourly data, rather than the pretended 5-minute rainfall data. Then, this thesis focuses on the selected data to characterize the temporal structure and extreme behaviour of rainfall. We analyze the sources of uncertainties of already "classical" multifractal methods for the parameter estimates, and we therefore developed their improvements considering e.g., the finite size of data samples and the limitation of sensor dynamics. These improvements are used to obtain proper multifractal characteristics of 5-minute high-resolution rainfall for several French departments (i.e., 38, 78, 83 and 94), and hence to raise the question of preicipitation evolution during the last decades in the context of climate change. This study is reinforced by the analysis of radar mosaics for three major events in the Paris region. Finally, this thesis highlights another application of the developed methods, i.e. for the karst hydrology. We discuss the multifractal characteristics of rainfall and runoff processes observed at the different resolutions in two karst watersheds on the south of France. Using daily, 30-minute and 3-minute measurements we analyse the rainfall-runoff relationships within the multifractal framework. This is a major step towards defining a rainfall-runoff multi-scale model of the karst watershed functioning

Nearly 300 years before the rise of a ‘Christianized,’ Eastern Roman Empire, generations of inhabitants in the Eastern Mediterranean and Near East had witnessed a considerable variety and evolution of religious thought. As a result of the expansion of Christian sects throughout the Near East and Mediterranean, in 325 CE, Emperor Constantine I convened a theological council to unite his vast kingdom in the East under a single religious creed. While revisions to the text of the first ‘Nicene Creed’ and subsequent councils would be organized, many dissenting factions refused to relinquish their long-held beliefs and traditions. Some of these ‘heterodox’ sects resisted the religious arm of the Empire and concealed their practices while continuing to worship in secrecy. Clues to the subversion of ‘orthodox’ ecclesiastical mandate may still persist in the mosaic programs of extant churches in the Mediterranean and Transjordan. In particular, the general design of mosaics in the Transjordan (e.g., the Petra Church, Petra; the Church of SS. Lot and Procopius, Khirbet al-Mukhayyat; and the Church of SS. Cosmas and Damian, Jerash) are somewhat similar, yet divergent from designs found within churches from the Italian Peninsula (e.g., the Theodorean Basilical Complex, Aquileia; the Church of San Vitale, Ravenna; and the Church of Sant’Apollinare in Classe, Classe). The purpose of this thesis is to use the principles of semiotic theory to re-evaluate the use of symbols and icons within sacred mosaic programs, juxtaposed against the historical and ecclesiastical context surrounding their creation.

Nearly 300 years before the rise of a 'Christianized,' Eastern Roman Empire, generations of inhabitants in the Eastern Mediterranean and Near East had witnessed a considerable variety and evolution of religious thought. As a result of the expansion of Christian sects throughout the Near East and Mediterranean, in 325 CE, Emperor Constantine I convened a theological council to unite his vast kingdom in the East under a single religious creed. While revisions to the text of the first 'Nicene Creed' and subsequent councils would be organized, many dissenting factions refused to relinquish their long-held beliefs and traditions. Some of these 'heterodox' sects resisted the religious arm of the Empire and concealed their practices while continuing to worship in secrecy. Clues to the subversion of 'orthodox' ecclesiastical mandate may still persist in the mosaic programs of extant churches in the Mediterranean and Transjordan. In particular, the general design of mosaics in the Transjordan (e.g., the Petra Church, Petra; the Church of SS. Lot and Procopius, Khirbet al-Mukhayyat; and the Church of SS. Cosmas and Damian, Jerash) are somewhat similar, yet divergent from designs found within churches from the Italian Peninsula (e.g., the Theodorean Basilical Complex, Aquileia; the Church of San Vitale, Ravenna; and the Church of Sant'Apollinare in Classe, Classe). The purpose of this thesis is to use the principles of semiotic theory to re-evaluate the use of symbols and icons within sacred mosaic programs, juxtaposed against the historical and ecclesiastical context surrounding their creation.

Le contexte de cette thèse est le recalage d'images endomicroscopiques. Le microendoscope multiphotonique fournit différentes trajectoires de balayage que nous considérons dans ce travail. Nous proposons d'abord une méthode de recalage non rigide dont l'estimation du mouvement est transformée en un problème d'appariement d'attributs dans le cadre des Log-Demons et d'ondelettes sur graphes. Nous étudions les ondelettes de graphe spectral (SGW) pour capturer les formes des images, en effet, la représentation des données sur les graphes est plus adaptée aux données avec des structures complexes. Nos expériences sur des images endomicroscopiques montrent que cette méthode est supérieure aux techniques de recalage d'images non rigides existantes. Nous proposons ensuite une nouvelle stratégie de recalage d'images pour les images endomicroscopiques acquises sur des grilles irrégulières. La transformée en ondelettes sur graphe est flexible et peut être appliquée à différents types de données, quelles que soient la densité de points et la complexité de la structure de données. Nous montrons également comment le cadre des Log-Demons peut être adapté à l'optimisation de la fonction objective définie pour les images acquises avec un échantillonnage irrégulier. / The context of this thesis is the image registration for endomicroscopic images. Multiphoton microendoscope provides different scanning trajectories which are considered in this work. First we propose a nonrigid registration method whose motion estimation is cast into a feature matching problem under the Log-Demons framework using Graph Wavelets. We investigate the Spectral Graph Wavelets (SGWs) to capture the shape feature of the images. The data representation on graphs is more adapted to data with complex structures. Our experiments on endomicroscopic images show that this method outperforms the existing nonrigid image registration techniques. We then propose a novel image registration strategy for endomicroscopic images acquired on irregular grids. The Graph Wavelet transform is flexible to apply on different types of data regardless of the data point densities and how complex the data structure is. We also show how the Log-Demons framework can be adapted to the optimization of the objective function defined for images with an irregular sampling.

No description available.