Thesis (Ph. D.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains vi, 95 p. : col. ill. Includes abstract. Includes bibliographical references (p. 89-93).

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Étendre le contenu visuel à une troisième dimension, ou capturer une scène dynamique en relief et en temps réel, a été un rêve pendant des décennies. C'est aujourd'hui un rêve qui devient réalité tant l'engouement suscité par ces nouvelles technologies est profond. Une part de plus en plus importante des films est effectivement produite en relief et de très nombreux cinémas sont maintenant équipés pour diffuser ce type d'images. Chez les particuliers également la technologie relief fait son apparition. Toutes ces installations sont pour le moment basées sur des technologies stéréoscopiques qui imposent aux utilisateurs le port de lunettes spéciales. Les technologies autostéréoscopiques, à l'inverse, permettentun affichage d'images reliefs sans lunettes. Ce travail de thèse s'inscrit dans un projet ANR " CamRelief " visant le développement des matériels et logiciels nécessaires à la production de contenus relief pour écrans autostéréoscopiques. Au sein de ce projet mon travail a consisté à caractériser des géométries de capture et de restitution d'images en relief, dans le but d'évaluer la qualité du relief restitué par les écrans autostéréoscopiques, tout en améliorant si possible leur confort visuel. Ce travail concerne donc la production de contenus relief de qualité en fonction d'un mode de restitution choisi et du rendu relief souhaité. Afin de valider ces contenus, des méthodes de caractérisation de la restitution du relief sont proposées.En commençant par décrire la perception du relief ainsi que les différents systèmes de diffusion existants et les applications visées, puis en introduisant les différentes géométries du relief illusoire, nous avons établi un modèle analytique de déformation du relief. A partir de celui-ci nous avons défini une méthodologie de spécification de la configuration de prise de vue nécessaire pour obtenir, sur un système d'affichage relief donné, la déformation du relief voulue. Nous avons présenté ensuite les différentes réalisations techniques réalisées grâce à cette méthodologie. Enfin nous avons proposé une méthode pour la validation pratique de nos résultats, mais aussi pour quantifier plusieurs données : la qualité d'un écran autostéréoscopique et d'un dispositif de prise de vue, la limite accommodation/convergence et la fatigue visuelle. Pour réaliser cela nous avons proposé un instrument nous permettant de caractériser la restitution du relief illusoire en multiscopie plane. Nous avons précisé les modalités de mise en place de cet instrument et enfin nous avons proposé différents protocoles expérimentaux pour l'accompagner. / Extending visual content with a third dimension, or capturing a dynamic scene in 3D and generating an optical duplicate of it in real-time, has been a dream over decades. All components (hardware and software) related to this viewing experience are collectively referred as three-dimensional television (3DTV). In this scheme, a fundamental element of stereoscopic and/or autostereoscopic image production is the geometrical analysis of shooting and viewing conditions in order to obtain a qualitative 3D perception experience.This work takes place in ANR project "CamRelief" which aimed at developing hardware and software needed to produce content for autostereoscopic displays. My work consists to characterize the viewing and shooting geometries to evaluate a qualitative 3D experience.Firstly, we describe 3D perception and the different existing rendering devices. Then, from the usual multiscopic rendering geometry and the classical, off-axis, coplanar, multipoint 3D shooting geometry, we firstly compare the perceived depth with the shot scene depth, for a couple of shooting and rendering devices. This yields a depth distortion model whose parameters are expressed from the geometrical characteristics of shooting and rendering devices. Then, we explain how to invert these expressions in order to design the appropriate shooting layout from a chosen rendering device and a desired effect of depth. Next, we introduce different technical achievements realized from this methodology. Finally we propose a framework to pratical validate our results and to quantify different data: quality of autostereoscopic display and shooting device, accommodation/convergence limit and visual tiredness. In this goal, we suggest a new instrument of characterization of the 3D perception on a given autostereoscopic display. We speficy the setting up modalities of this instrument and we introduce different experimental protocols to use it.

Doktorin--Technischen Wissenschaften--Zürich--Eidgenössische technische Hochschule, 2005.

Th. 3e cycle--Sci. de l'éduc. et de la communication, option audiovisuel--Paris 13, 1978. / Glossaire.

The variability of chemical parameters over the landscape was examined in this research. A terrain hierarchy based on genetic geo-morphological unit concepts was developed in two Quaternary landscapes in the Fraser Valley and in the Peace River area in British Columbia. The relative variability within and betueen different hierarchical units ranging from "sites" to "landform units" to "landform unit types" was compared. The variability was large in all units but was smaller at the site scale than at the landform unit scale, within single landform units chemical parameters were shown to be closely related to type of drainage. Available Ca, Mg, Na, H, and Si were found to be the most important differentiating parameters for all units. Site categories which reflected units of similar parent material, form, and inferred genesis were determined by application of a cluster analysis procedure. Sites grouped by this method were not coextensive with individual land-form units, thus suggesting that the environmental imprint on the.chemical conditions was not as strong as that of the genesis. The best grouping was obtained with the Peace River data where more natural conditions prevailed. A data screening through factor analysis prior to the grouping improved the landform unit type classification in the Fraser Valley where the chemical conditions were complicated by a more complex and intensive land use pattern. Multispectral remote sensing techniques were used to assess the potential of predicting chemical ground conditions from spectral measurements. Multispectral photography combined with density slicing and additive color viewing techniques were used to quantify chemical ground conditions on the photographic image. Areas'of different soil moisture and percent Carbon content could readily be identified and quantified by this means. Exchangeable Ca, Mg, and Na could partially be differentiated probably as a result of direct correlation with Carbon. The wider band photography (color k00-700 nm and color IR 500-900 nm wavelength range) produced better results than the narrow band black and white images (50D-6QD nm and 6DD-7DD nm wavelength range). The trends in detecting chemicals were consistent for both vegetated and non-vegetated surfaces; the sliced color film image was slightly more useful for analyzing exposed soil surfaces, while the sliced color IR image proved to be more useful for the interpretation of vegetated surfaces. Direct digital reflection measurements were made with a multichannel spectrometer from the air, and Dn soil samples on the ground and in the laboratory. In the field the A-DO-1000 nm spectral wavelength range was used and the laboratory analysis was extended to the 35D-25D0 nm wavelength range. Only bare soil surfaces were investigated. Correlation and regression analysis revealed that % Carbon, % Fe, exchangeable Mg, and exchangeable K could be predicted from spectral reflection values. There is evidence thattthe spectral-chemical relationship follows a curvilinear function, but adequate predictions were obtained with linear relationships at low chemical concentration levels. Despite differences in measuring techniques similar regression trends were obtained for all three methods and the 50D-11D0 nm wavelength range was found to be most useful in this analysis. The total spectral reflectance curve was found to be of importance since soils from similar parent materials produced characteristic curves which could readily be differentiated by all three types of measurements. / Arts, Faculty of / Geography, Department of / Graduate

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Thesis (Ph. D.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

Texte remanié de: Diss.--Fakultät für Orientalistik und Altertumswissenschaft--Heidelberg--Ruprecht-Karl-Universität, 1989. / Notes bibliogr. Index.

Texte remanié de: Dissertation--Bonn--Rheinische Friedrich-Wilhelms-Universität, 1993. / Bibliogr. p. VII-VIII et notes bibliogr.