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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Transmodalité de flux d'images de synthèse / Synthetic picture stream transmodality

Rocher, Pierre-Olivier 31 October 2014 (has links)
Ces dernières années, l’utilisation de la vidéo comme support de diffusion de l’information est devenue prépondérante. Selon certains analystes, d’ici 2017, environ 90% de la bande passante mondiale sera consommée par des services utilisant des flux vidéos. Basées sur ce genre de services, les solutions de cloud gaming se démocratisent. Ces solutions ont été imaginées dans un contexte de développement fort du paradigme de cloud computing, et elles ont été dopées par la prolifération des terminaux mobiles ainsi que par la qualité des réseaux qui ne cesse de croître. Les technologies mises en œuvre dans ce type de solutions se réfèrent au rendu à distance. Pour permettre au plus grand nombre l’accès à ce type d’applications, mais aussi pour maximiser le nombre de clients par serveur, il est primordial de maîtriser au mieux la bande passante nécessaire au bon fonctionnement du service. Toutes les solutions de cloud gaming existantes utilisent une compression vidéo pour la transmission des images générées sur un serveur et à destination d’un client : le pixel règne en maître. Néanmoins, il existe bien d’autres façons de représenter une image numérique, notamment de manière paramétrique. Un certain nombre de travaux – à la fois sur l’image et la vidéo – montrent que cette approche est viable. Dans cette thèse, nous proposons un espace de représentation hybride afin de réduire le débit binaire. Notre approche repose à la fois sur une approche pixel, mais aussi sur une approche paramétrique pour la compression d’un même flux vidéo. L’utilisation de deux systèmes de compression nécessite la définition de zones, auxquelles s’appliqueront les différents encodeurs. Pour le cas d’utilisation choisi, l’utilisateur étant un joueur impliqué de manière active dans la chaîne de rendu, il est intéressant d’utiliser un partitionnement de l’image dépendant des zones ou se porte son attention. Pour déterminer les zones importantes à ses yeux, un eye-tracker a été utilisé sur plusieurs jeux et par plusieurs testeurs. Cette étude permet de mettre en avant différentes corrélations, tant au niveau des caractéristiques des images que du type de jeu utilisé. Cette étude permet de connaître les zones que le joueur regarde ou ne regarde pas directement (obtention des « cartes d’attention sélective »), et ainsi de gérer les encodeurs en conséquence. Nous établissons ensuite l’architecture et l’implémentation d’un tel encodeur multimodal (que nous appelons « transmodeur ») afin d’établir la preuve de réalisation d’un tel encodeur. Profitant alors de la maîtrise complète de l’implémentation, nous nous livrons ensuite à l’analyse de l’influence des paramètres de notre transmodeur quant à son efficacité au moyen d’une étude objective. Le transmodeur a été intégré dans la chaîne de rendu utilisée par le projet XLcloud. Un certain nombre d’améliorations (au niveau des performances notamment) seront nécessaires pour une utilisation en production, mais il est dès à présent possible de l’utiliser de manière fluide en se limitant à des résolutions spatiales légèrement inférieures au 720p et à 30 images par seconde / The use of video as an information dissemination support has become preponderant during the last few years. According to some analysts, by 2017 approximately 90% of the world's bandwidth will be consumed by video streaming services. These services have encouraged cloud gaming solutions to become more democratic. Such solutions have been devised in the context of strong development of the cloud-computing paradigm, and they were driven by the proliferation of mobile devices as well as growing network quality. The technologies used in this kind of solutions refer to as remote rendering. They allow the execution of multiple applications, while maximizing the number of clients per server. Thus, it is essential to control the necessary bandwidth to allow the required functionality of various services. The existing cloud gaming solutions in the literature use various methods of video compression to transmit images between sever and clients (pixels reigns supreme). However, there are various other ways of encoding digital images, including parametric map storage and a number of studies encourage this approach (for both image and video). In this thesis, we propose a hybrid representation of space in order to reduce the bit rate. Our approach utilizes both pixel and parametric approaches for the compression of video stream. The use of two compression techniques requires defining the area to be covered by different encoders. This is accomplished by including user to the life cycle of rendering, and attending to the area mostly concerned to the user. In order to identify the area an eye-tracker device was used on several games and several testers. We also establish a correlation between the characteristics of images and the type of game. This helps to identify areas that the player looks directly or indirectly (“maps of selective attention"), and thus, encoders are manager accordingly. For this thesis, we details and implement the architecture and algorithms for such multi-model encoder (which we call "transmodeur") as proof of concept. We also provide an analytical study of out model and the influence of various parameters on transmodeur and describe in effectiveness through an objective study. Our transmodeur (rendering system) has been successfully integrated into XLcloud project for rendering purposes. A number of improvement (especially in performance) will be required for production use, but it is now possible to use it smoothly using spatial resolutions slightly lower than 720p at 30 frames per second
2

Vizuální efekty ve 3D aplikacích / Visual Effects in 3D Applications

Duží, Martin January 2014 (has links)
This master's thesis deals with the creation of visual effects in 3D graphics applications. Rendering scenes using rasterization method and OpenGL library is assumed. The theoretical part describes several selected effects and then analyzes the approach used for their implementation. It focuses on the principles of rendering passes. Subsequently, the thesis focuses on the development of a software library which aims to simplify the process of programming effects. The resulting library reduces the time and knowledge required for the creation of effects. Automatic shader code generation is performed. Substantial feature is also the possibility to combine definitions of effects into a single unit.
3

A porosity-based model for coupled thermal-hydraulic-mechanical processes

Liu, Jianxin January 2010 (has links)
[Truncated abstract] Rocks, as the host to natural chains of coupled thermal, hydraulic and mechanical processes, are heterogeneous at a variety of length scales, and in their mechanical properties, as well as in the hydraulic and thermal transport properties. Rock heterogeneity affects the ultimate hydro-carbon recovery or geothermal energy production. This heterogeneity has been considered one important and difficult problem that needs to be taken into account for its effect on the coupled processes. The aim of this thesis is to investigate the effect of rock heterogeneity on multi-physical processes. A fully coupled finite element model, hereinafter referred to as a porosity-based model (PBM) was developed to characterise the thermal-hydraulic-mechanical (THM) coupling processes. The development of the PBM consists of a two-staged workflow. First, based on poromechanics, porosity, one of the inherent rock properties, was derived as a variant function of the thermal, hydraulic and mechanical effects. Then, empirical relations or experimental results, correlating porosity with the mechanical, hydraulic and thermal properties, were incorporated as the coupling effects. In the PBM, the bulk volume of the model is assumed to be changeable. The rate of the volumetric strain was derived as the difference of two parts: the first part is the change in volume per unit of volume and per unit of time (this part was traditionally considered the rate of volumetric strain); and the second is the product of the first part and the volumetric strain. The second part makes the PBM a significant advancement of the models reported in the literature. ... impact of the rock heterogeneity on the hydro-mechanical responses because of the requirement of large memory and long central processing unit (CPU) time for the 3D applications. In the 2D PBM applications, as the thermal boundary condition applied to the rock samples containing some fractures, the pore pressure is generated by the thermal gradient. Some pore pressure islands can be generated as the statistical model and the digital image model are applied to characterise the initial porosity distribution. However, by using the homogeneous model, this phenomenon cannot be produced. In the 3D PBM applications, the existing fractures become the preferential paths for the fluid flowing inside the numerical model. The numerical results show that the PBM is sufficiently reliable to account for the rock mineral distribution in the hydro-mechanical coupling processes. The applications of the statistical method and the digital image processing technique make it possible to visualise the rock heterogeneity effect on the pore pressure distribution and the heat dissipation inside the rock model. Monitoring the fluid flux demonstrates the impact of the rock heterogeneity on the fluid product, which concerns petroleum engineering. The overall fluid flux (OFF) is mostly overestimated when the rock and fluid properties are assumed to be homogeneous. The 3D PBM application is an example. As the rock is heterogeneous, the OFF by the digital core is almost the same as that by the homogeneous model (this is due to that some fractures running through the digital core become the preferential path for the fluid flow), and around 1.5 times of that by the statistical model.
4

Conception et évaluation d'un micromonde de Programmation Orientée-Objet fondé sur un jeu de construction et d'animation 3D / Design and evaluation of an Object-Oriented Programming microworld based on a 3D construction and animation game

Djelil, Fahima 14 December 2016 (has links)
Les micromondes de programmation sont des environnements restreints et interactifs, dans lesquels l’apprenant apprend en interagissant avec des entités visuelles ou tangibles, sémantiquement liées à des concepts de programmation formels. Ils favorisent l’assimilation de connaissances et la compréhension de concepts abstraits de programmation au moyen de métaphores visuelles et d’expériences ludiques. Cette thèse tente d’apporter des avancées théoriques et méthodologiques sur la conception et l’évaluation de tels environnements, qui sont connus pour avoir un grand potentiel sur l’apprentissage sans que cela ne soit démontré. Les micromondes étant des environnements d’apprentissage par le jeu, nous avons tout d’abord examiné la question du jeu et son lien à l’apprentissage. En nous appuyant sur une revue de la littérature, nous avons souligné au même titre que certains auteurs, la nécessité de distinguer le jeu-game (l’artefact informatique) du jeu-play (la situation qui découle des interactions avec le jeu-game). Le but étant de situer l’apprentissage et d’aboutir à des éléments de conception et d’évaluation de l’apprentissage. Nous nous sommes ensuite intéressés aux recherches en didactique de l’Informatique, afin d’identifier les approches d’enseignement les plus répandues visant à palier les difficultés d’apprentissage de la Programmation Orientée-Objet ( POO ) rencontrées par des débutants. Nous avons défini une nouvelle approche didactique pour l’introduction de la POO . Suite à cela, nous avons défini les dimensions de conception d’un micromonde, que nous désignons comme un système de représentation transitionnel, dans lequel l’apprenant développe des connaissances sur les concepts formels et abstraits de la programmation, suite à ses interactions avec l’interface du micromonde. Les avancées théoriques et méthodologiques apportées ont été mises en œuvre dans un nouveau micromonde de POO fondé sur un jeu de construction et d’animation 3D appelé PrOgO. PrOgO implémente un système de représentation transitionnel, dans lequel les concepts fondamentaux de la POO sont représentés par des graphiques 3D visuels et interactifs. Il crée un jeu-play qui découle des interactions de l’apprenant avec son interface. Jouer avec PrOgO consiste à imaginer, créer et animer des constructions 3D significatives. PrOgO peut également être déployé dans une classe multi-dispositifs, grâce au framework Tactileo conçu à cet effet. Dans l’évaluation de l’apprentissage, nous utilisons des méthodes relevant de l’analyse de l’apprentissage, par la collecte et l’analyse de traces d’interaction pour la classification et la caractérisation des apprenants. En complément à cela, nous examinons l’état des connaissances d’apprenants, au travers de tests de vérification de connaissances. Nous tentons également d’identifier par l’analyse statistique, les actions et les comportements d’apprenants qui déterminent leur progression dans l’évaluation pré/post de l’acquisition des connaissances. / Programming microworlds are small and interactive environments, in which the learner learns from his interactions with visual or tangible entities having a strong semantic link with formal programming concepts. They promote knowledge assimilation and abstract programming concepts understanding by the use of visual metaphors and play. This thesis attempts to contribute to theoretical and methodological advances regarding the design and the assessment of such environments, which are known to have a great potential on learning without any evidence on that. As microworlds are game based learning environments, we first examined the gaming issue and its relation to learning. Based on a literature review, we emphasized as some authors, the need to distinguish between the game (the computing artefact) and the play (the situation that is triggered by the interactions with the game). The purpose is to analyze learning and establish concepts that will guide the design and the evaluation of learning. Then we reviewed some research on Computer Science Education, with the view to identify some widespread teaching approaches that address beginners’ difficulties in learning Object-Oriented Programming (OOP). We defined a new didactic approach for OOP introduction. We then defined the design dimensions of a microworld, we refer to as a transitional representation system, in which the learner develops knowledge on programming abstract and formal concepts, as a result to his interactions with the microworld interface. We have implemented the theoretical and methodological advances we provided, in a new OOP microworld based on a 3D constructive and animation game called PrOgO. PrOgO implements a transitional representation system, in which basic OOP concepts are depicted with visual and interactive 3D graphics. It enables play that arises from the learner’s interactions with its interface. Playing with PrOgO involves to imagining, creating and animating significant 3D constructions. PrOgO can be also deployed within a multi-device classroom through the Tactileo framework, we designed for that purpose. In the evaluation of learning, we use methods belonging to learning analytics by the collection and the analysis of digital interaction logs, with the view to classify and characterize learners. In addition to this, we examine the state of learners’ knowledge through test knowledge verifications. We also attempt to examine through statistical analysis, the learners’ actions and behaviours that affect their progress in pre/post evaluations of gained knowledge.
5

Knihovna pro efektivní záznam videa v 3D aplikaci / Library for Efficient Video Capture in 3D Application

Pospíšil, Petr January 2012 (has links)
This thesis deals with library for recording video in the background of 3D application. A library is designed to work under the Microsoft Windows and Linux operation systems.  It records image and also sound. Image recording is supported in OpenGL, Direct3D9, Direct3D10 and Direct3D11. To reduce video data size, library supports image compression using MJPG codec. Audio is recorded by WaveForm audio, Windows Core Audio or ALSA. Recorded sound is for whole operation system. A library is able to record up to two audio streams to accommodate possible microphone input. It can mix audio data together if needed. Output data are then written into AVI file. It is possible to write own text information as overlay that is rendered as part of application screen output.

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