Le trafic vidéo s’est considérablement accru et est prévu de doubler pour représenter 82% du trafic Internet d’ici 2021. Une telle croissance surcharge les fournisseurs de services Internet (ISP), nuisant à la Qualité d’Expérience (QoE) perçue par les utilisateurs. Cette thèse vise à améliorer la QoE des utilisateurs de streaming vidéo sans hypothèse de changement d’infrastructure physique des opérateurs. Pour cela, nous combinons les technologies de caching réseau, de streaming HTTP adaptatif (HAS), et de transport multipath. Nous explorons d’abord l’interaction entre HAS et caching, pour montrer que les algorithmes d’adaptation de qualité vidéo ont besoin de savoir qu’il y a un cache et ce qui y est stocké, et proposons des algorithmes bénéficiant de cette connaissance. Concluant sur la difficulté d’obtenir la connaissance de l’état du cache, nous étudions ensuite un système de distribution vidéo à large échelle, où les caches sont représentés par un réseau de distribution du contenu (CDN). Un CDN déploie des caches à l’intérieur des réseaux des ISP, et dispose de ses propres serveurs externes. L’originalité du problème vient de l’hypothèse que nous faisons que l’utilisateur est simultanément connecté à 2 ISP. Ceci lui permet d’accéder en multipath aux serveurs externes aux ISP (pouvant ainsi accroître le débit mais chargeant plus les ISP), ou streamer le contenu depuis un cache plus proche mais avec un seul chemin. Ce désaccord entre les objectifs du CDN et de l’ISP conduit à des performances sous-optimales. Nous développons un schéma de collaboration entre ISP et CDN qui permet de nous rapprocher de l’optimal dans certains cas, et discutons l’implémentation pratique. / Video traffic volume grew considerably in recent years and is forecasted to reach 82% of the total Internet traffic by 2021, doubling its net volume as compared to today. Such growth overloads Internet Service Providers' networks (ISPs), which negatively impacts users' Quality of Experience (QoE). This thesis attempts to tackle the problem of improving users' video QoE without relying on network upgrades. For this, we have chosen to combine such technologies as in-network caching, HTTP Adaptive Streaming (HAS), and multipath data transport. We start with exploration of interaction between HAS and caching; we confirm the need of cache-awareness in quality adaptation algorithms and propose such an extension to a state-of-the-art optimisation-based algorithm. Concluding on the difficulty of achieving cache-awareness, we take a step back to study a video delivery system on a large scale, where in-network caches are represented by Content Delivery Networks (CDNs). They deploy caches inside ISPs and dispose of their own outside video servers. As a novelty, we consider users to have a simultaneous connectivity to several ISP networks. This allows video clients either to access outside multipath servers with aggregate bandwidth (which may increase their QoE, but will also bring more traffic into ISP), or stream their content from a closer cache through only single connectivity (bringing less traffic into ISP). This disagreement in ISP and CDN objectives leads to suboptimal system performance. In response to this, we develop a collaboration scheme between two actors, performance of which can approach optimal boundary for certain settings, and discuss its practical implementation.

Video streaming is widely recognized as the next Internet killer application. It was not one of the Internet's original target applications and its protocols (TCP in particular) were tuned mainly for e efficient bulk file transfer. As a result, a significant effort has focused on the development of UDP-based special protocols for streaming multimedia on the Internet. Recently, there has been a shift in video streaming from UDP to TCP, and specifically to HTTP. HTTP streaming provides a very attractive platform for video distribution on the Internet mainly because it can utilize all the current Internet infrastructure. In this thesis we make the argument that the marriage between HTTP streaming and the current Internet infrastructure can create many problems and inefficiencies. In order to solve these issues, we provide a set of techniques and protocols that can help both the network and end-hosts to make better decisions to improve video streaming quality. The thesis makes the following contributions: - We conduct a characterization study of popular commercial streaming services on mobile platforms. Our study shows that streaming services make different design decisions when implementing video players on different mobile platforms. We show that this can lead to several inefficiencies and undesirable behaviors specially when several clients compete for bandwidth in a shared bottleneck link. - Fairness between traffic flows has been preserved on the Internet through the use of TCP. However, due to the dynamics of adaptive video players and the lack of standard client adaptation techniques, fairness between multiple competing video flows is still an open issue of research. Our work extends the definition of standard bitrate fairness to utility fairness where utility is the Quality of Experience (QoE) of a video stream. We define QoE max-min fairness for a set of adaptive video flows competing for bandwidth in a network and we develop an algorithm that computes the set of bitrates that should be assigned to each stream to achieve fairness. We design and implement a system that can apply QoE fairness in home networks and evaluate the system on a real home router. - A well known problem that has been associated with TCP traffic is the buffer bloat problem. We use an experimental setup to show that adaptive video flows can cause buffer bloat which can significantly harm time sensitive applications sharing the same bottleneck link with video traffic. In addition, we develop a technique that can be used by video players to mitigate this problem. We implement our technique in a real video player and evaluate it on our testbed. - With the increasing popularity of video streaming on the Internet, the amounts of traffic on the peering links between video streaming providers and Internet Service Providers (ISPs) have become the source of many disputes. Hybrid CDN/P2P streaming systems can be used to reduce the amounts of traffic on the peering links by leveraging users upload bandwidth to redistribute some of the load to other peers. We develop an analysis for hybrid CDN/P2P systems that broadcast live adaptive video streams. The analysis helps the CDN to make better decisions to optimize video quality for its users.

This diploma thesis focuses on multimedia streaming from IP cameras. Its main goal is to explain theoretical background of real-time streaming via computer networks, and describe development of a recording system. This recording system is meant to be used mainly in schools for lecture recording purposes. The thesis contains description on how a recording server application and web-based management system were developed. The theoretical part explains topics related to multimedia streaming, networking, and multimedia procesing, such as real-time streaming protocols, encoding, compression, network latency, network congestion and many others.

No description available.

Um die ständig wachsenden Anforderungen zur Übertragung von Live Video Streams im Internet zu erfüllen werden kosteneffektive und resourceneffiziente Lösungen benötigt. Eine adäquate Lösung bietet die Peer-to-Peer (P2P) Streaming Architektur an, welche bereits heute in unterschiedlichsten Systemen zum Einsatz kommt. Solche Systeme erfordern von der Streaming Quelle nur moderate Bandbreiten, da die Nutzer (bzw. Peers) ihre eigene Bandbreite zur Verbreitung des Streams einbringen. Dazu werden die Peers oberhalb der Internetarchitektur zu einem Overlay verbunden. Das geplante Verlassen, sowie der ungewollte Absturz von Peers (genannt Churn) kann das Overlay schädigen und den Empfang einiger Peers unterbrechen. Weitaus kritischer sind Angriffe auf die Verfügbarkeit des Systems indem relevante Knoten des Overlays von Angreifern attackiert werden, um die Verteilung des Streams gezielt zu stören. Um Overlays zu konstruieren, die robust gegenüber Churn sind, nutzen so genannte pull-basierte P2P Streaming Systeme eine Mesh Topologie um jeden Peer über mehrere Pfade mit der Quelle zu verbinden. Peers fordern regelmäßig Teile des Videos, sog. Chunks, von ihren Partnern im Overlay an. Selbst wenn einige Partner plötzlich nicht mehr im System verfügbar sind kann ein Peer alle Chunks von den verbleibenden Nachbarn beziehen. Um dies zu ermöglichen tauschen Peers regelmäßig sog. Buffer Maps aus. Diese kleinen Pakete enthalten Informationen über die Verfügbarkeit von Chunks im Puffer eines Peers. Um dadurch entstehende Latenzen und den zusätzlichen Mehraufwand zu reduzieren wurden hybride Systeme entwickelt. Ein solches System beginnt pull-basiert und formt mit der Zeit einen Baum aus einer kleinen Untermenge aller Peers um Chunks ohne explizite Anfrage weiterzuleiten. Unglücklicherweise sind sowohl pull-basierte, als auch hybride Systeme anfällig gegenüber Denial-of-Service Angriffen (DoS). Insbesondere fehlen Maßnahmen zur Abschwächung von DoS Angriffen auf die Partner der Quelle. Die genannten Angriffe werden weiterhin dadurch erleichtert, dass die Identität der Quelle-nahen Knoten akkurat aus den ausgetauschten Buffer Maps extrahiert werden kann. Hybride Systeme sind außerdem anfällig für Angriffe auf den zugrundeliegenden Baum. Aufgrund der schwerwiegenden Auswirkungen von DoS Angriffen auf pull-basierte, sowie hybride Systeme stellen wir drei Gegenmaßnahmen vor. Zuerst entwickeln wir das Striping Schema zur Abschwächung von DoS Angriffen auf die Partner der Quelle. Hierbei werden Peers dazu angeregt ihre Chunk-Anfragen an unterschiedliche Partner zu senden. Als zweites entwickeln wir das SWAP Schema, welches Peers dazu bringt proaktiv ihre Partner zu wechseln um Angreifer daran zu hindern die Quellenahe zu identifizieren. Als drittes entwickeln wir RBCS, einen widerstandsfähigen Baum zur Abschwächung von DoS Angriffen auf hybride Systeme. Da bisher kein Simulator für die faire Evaluation von P2P-basierten Live Video Streaming Algorithmen verfügbar war, entwickeln wir OSSim, ein generalisiertes Simulations-Framework für P2P-basiertes Video Streaming. Des weiteren entwickeln wir etliche Angreifermodelle sowie neuartige Resilienzmetriken on OSSim. Ausgiebige Simulationsstudien zeigen, dass die entwickelten Schemata signifikant die Widerstandsfähigkeit von pull-basierten und hybriden Systemen gegenüber Churn und DoS Angriffen erhöhen. / The constantly growing demand to watch live videos over the Internet requires streaming systems to be cost-effective and resource-efficient. The Peer-to-Peer (P2P) streaming architecture has been a viable solution with various deployed systems to date. The system only requires a modest amount of bandwidth from the streaming source, since users (or peers) contribute their bandwidth to disseminate video streams. To enable this, the system interconnects peers into an overlay. However, churn–meaning the leaving and failing of peers–can break the overlay, making peers unable to receive the stream. More severely, an adversary aiming to sabotage the system can attack relevant nodes on the overlay, disrupting the stream delivery. To construct an overlay robust to churn, pull-based P2P streaming systems use a mesh topology to provide each peer with multiple paths to the source. Peers regularly request video chunks from their partners in the overlay. Therefore, even if some partners are suddenly absent, due to churn, a peer still can request chunks from its remaining partners. To enable this, peers periodically exchange buffer maps, small packets containing the availability information of peers’ video buffers. To reduce latency and overhead caused by the periodic buffer map exchange and chunk requests, hybrid systems have been proposed. A hybrid system bootstraps from a pull-based one and gradually forms a tree backbone consisting of a small subset of peers to deliver chunks without requests. Unfortunately, both pull-based and hybrid systems lack measures to mitigate Denial-of-Service (DoS) attacks on head nodes (or the source’s partners). More critically, they can be identified accurately by inferring exchanged buffer maps. Furthermore, hybrid systems are vulnerable to DoS attacks on their backbones. Since DoS attacks can badly affect both pull-based and hybrid systems, we introduce three countermeasures. First, we develop the striping scheme to mitigate DoS attacks targeting head nodes. The scheme enforces peers to diversify their chunk requests. Second, to prevent attackers from identifying head nodes, we develop the SWAP scheme, which enforces peers to proactively change their partners. Third, we develop RBCS, a resilient backbone, to mitigate DoS attacks on hybrid systems. Since a simulator for a fair evaluation is unavailable so far, we develop OSSim, a general-purpose simulation framework for P2P video streaming. Furthermore, we develop several attacker models and novel resilience metrics in OSSim. Extensive simulation studies show that the developed schemes significantly improve the resilient of pull-based and hybrid systems to both churn and DoS attacks.

Dans cette thèse on considère deux modèles de calcul qui abordent des problèmes qui se posent lors du traitement des grosses données. Le premier modèle est le modèle de streaming. Lors du traitement des grosses données, un accès aux données de façon aléatoire est trop couteux. Les algorithmes de streaming ont un accès restreint aux données: ils lisent les données de façon séquentielle (par passage) une fois ou peu de fois. De plus, les algorithmes de streaming utilisent une mémoire d'accès aléatoire de taille sous-linéaire dans la taille des données. Le deuxième modèle est le modèle de communication. Lors du traitement des données par plusieurs entités de calcul situées à des endroits différents, l'échange des messages pour la synchronisation de leurs calculs est souvent un goulet d'étranglement. Il est donc préférable de minimiser la quantité de communication. Un modèle particulier est la communication à sens unique entre deux participants. Dans ce modèle, deux participants calculent un résultat en fonction des données qui sont partagées entre eux et la communication se réduit à un seul message. On étudie les problèmes suivants: 1) Les couplages dans le modèle de streaming. L'entrée du problème est un flux d'arêtes d'un graphe G=(V,E) avec n=|V|. On recherche un algorithme de streaming qui calcule un couplage de grande taille en utilisant une mémoire de taille O(n polylog n). L'algorithme glouton remplit ces contraintes et calcule un couplage de taille au moins 1/2 fois la taille d'un couplage maximum. Une question ouverte depuis longtemps demande si l'algorithme glouton est optimal si aucune hypothèse sur l'ordre des arêtes dans le flux est faite. Nous montrons qu'il y a un meilleur algorithme que l'algorithme glouton si les arêtes du graphe sont dans un ordre uniformément aléatoire. De plus, nous montrons qu'avec deux passages on peut calculer un couplage de taille strictement supérieur à 1/2 fois la taille d'un couplage maximum sans contraintes sur l'ordre des arêtes. 2) Les semi-couplages en streaming et en communication. Un semi-couplage dans un graphe biparti G=(A,B,E) est un sous-ensemble d'arêtes qui couple tous les sommets de type A exactement une fois aux sommets de type B de façon pas forcement injective. L'objectif est de minimiser le nombre de sommets de type A qui sont couplés aux même sommets de type B. Pour ce problème, nous montrons un algorithme qui, pour tout 0<=ε<=1, calcule une O(n^((1-ε)/2))-approximation en utilisant une mémoire de taille Ô(n^(1+ε)). De plus, nous montrons des bornes supérieures et des bornes inférieurs pour la complexité de communication entre deux participants pour ce problème et des nouveaux résultats concernant la structure des semi-couplages. 3) Validité des fichiers XML dans le modèle de streaming. Un fichier XML de taille n est une séquence de balises ouvrantes et fermantes. Une DTD est un ensemble de contraintes de validité locales d'un fichier XML. Nous étudions des algorithmes de streaming pour tester si un fichier XML satisfait les contraintes décrites dans une DTD. Notre résultat principal est un algorithme de streaming qui fait O(log n) passages, utilise 3 flux auxiliaires et une mémoire de taille O(log^2 n). De plus, pour le problème de validation des fichiers XML qui décrivent des arbres binaires, nous présentons des algorithmes en un passage et deux passages qui une mémoire de taille sous-linéaire. 4) Correction d'erreur pour la distance du cantonnier. Alice et Bob ont des ensembles de n points sur une grille en d dimensions. Alice envoit un échantillon de petite taille à Bob qui, après réception, déplace ses points pour que la distance du cantonnier entre les points d'Alice et les points de Bob diminue. Pour tout k>0 nous montrons qu'il y a un protocole presque optimal de communication avec coût de communication Ô(kd) tel que les déplacements des points effectués par Bob aboutissent à un facteur d'approximation de O(d) par rapport aux meilleurs déplacements de d points. / In this PhD thesis, we consider two computational models that address problems that arise when processing massive data sets. The first model is the Data Streaming Model. When processing massive data sets, random access to the input data is very costly. Therefore, streaming algorithms only have restricted access to the input data: They sequentially scan the input data once or only a few times. In addition, streaming algorithms use a random access memory of sublinear size in the length of the input. Sequential input access and sublinear memory are drastic limitations when designing algorithms. The major goal of this PhD thesis is to explore the limitations and the strengths of the streaming model. The second model is the Communication Model. When data is processed by multiple computational units at different locations, then the message exchange of the participating parties for synchronizing their calculations is often a bottleneck. The amount of communication should hence be as little as possible. A particular setting is the one-way two-party communication setting. Here, two parties collectively compute a function of the input data that is split among the two parties, and the whole message exchange reduces to a single message from one party to the other one. We study the following four problems in the context of streaming algorithms and one-way two-party communication: (1) Matchings in the Streaming Model. We are given a stream of edges of a graph G=(V,E) with n=|V|, and the goal is to design a streaming algorithm that computes a matching using a random access memory of size O(n polylog n). The Greedy matching algorithm fits into this setting and computes a matching of size at least 1/2 times the size of a maximum matching. A long standing open question is whether the Greedy algorithm is optimal if no assumption about the order of the input stream is made. We show that it is possible to improve on the Greedy algorithm if the input stream is in uniform random order. Furthermore, we show that with two passes an approximation ratio strictly larger than 1/2 can be obtained if no assumption on the order of the input stream is made. (2) Semi-matchings in Streaming and in Two-party Communication. A semi-matching in a bipartite graph G=(A,B,E) is a subset of edges that matches all A vertices exactly once to B vertices, not necessarily in an injective way. The goal is to minimize the maximal number of A vertices that are matched to the same B vertex. We show that for any 0<=ε<=1, there is a one-pass streaming algorithm that computes an O(n^((1-ε)/2))-approximation using Ô(n^(1+ε)) space. Furthermore, we provide upper and lower bounds on the two-party communication complexity of this problem, as well as new results on the structure of semi-matchings. (3) Validity of XML Documents in the Streaming Model. An XML document of length n is a sequence of opening and closing tags. A DTD is a set of local validity constraints of an XML document. We study streaming algorithms for checking whether an XML document fulfills the validity constraints of a given DTD. Our main result is an O(log n)-pass streaming algorithm with 3 auxiliary streams and O(log^2 n) space for this problem. Furthermore, we present one-pass and two-pass sublinear space streaming algorithms for checking validity of XML documents that encode binary trees. (4) Budget-Error-Correcting under Earth-Mover-Distance. We study the following one-way two-party communication problem. Alice and Bob have sets of n points on a d-dimensional grid [Δ]^d for an integer Δ. Alice sends a small sketch of her points to Bob and Bob adjusts his point set towards Alice's point set so that the Earth-Mover-Distance of Bob's points and Alice's points decreases. For any k>0, we show that there is an almost tight randomized protocol with communication cost Ô(kd) such that Bob's adjustments lead to an O(d)-approximation compared to the k best possible adjustments that Bob could make.

The provision of online music streaming services and the management of copyright in the light of the Directive 2014/26/EU and its implementation in the Czech Republic and Denmark Abstract This thesis presents an insight into the management of copyright in musical works, with particular focus on their use in provision of online streaming services, together with the discernment of the individual aspects of such management in the context of changes brought about by the Directive 2014/26/EU and its implementation in the Czech Republic and Denmark. The aim of this thesis is to primarily describe the various models of copyright management and their importance for both the users of works and the right holders in the contemporary era of digital uses, and at the same time to analyse the individual legislative interventions into these models, confront them and infer possible de lege ferenda implications. The introductory part of the thesis also describes the streaming technology itself, especially with regard to its copyright aspects, whose grasp is essential for a proper description of the different modes of protection and application of copyright. The thesis is divided into eight chapters. The first chapter describes the historical development of copyright protection of works in the digital environment. The...

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2017-12-05T15:33:15Z No. of bitstreams: 1 Jorge Otávio Pinto Pouey de Oliveira_.pdf: 1107226 bytes, checksum: 9af9084c859cf494da3fffc258c8d826 (MD5) / Made available in DSpace on 2017-12-05T15:33:15Z (GMT). No. of bitstreams: 1 Jorge Otávio Pinto Pouey de Oliveira_.pdf: 1107226 bytes, checksum: 9af9084c859cf494da3fffc258c8d826 (MD5) Previous issue date: 2017-07-06 / Nenhuma / O uso constante de plataformas de streaming para acessar os mais diversos conteúdos é uma realidade. Diante deste quadro, podemos também enxergar estas plataformas assumindo funções neste ambiente digital que anteriormente eram realizadas pelos meios tradicionais de comunicação. Uma destas funções que podemos cogitar é a curadoria musical. O objetivo desta dissertação de mestrado é propor uma investigação e imersão na plataforma de streaming musical, o Spotify, e analisar de que forma ela opera para divulgar os seus conteúdos musicais, criando assim, através de suas estratégias curatoriais, uma noção de um novo jornalismo cultural. As bibliografias acionadas tematizam cultura da convergência, jornalismo cultural, radiojornalismo hipermidiático e curadoria, além de um questionário sobre hábitos de novos padrões de consumo de música seguido da respectiva análise. Dessa forma, este trabalho busca contribuir tanto para desmistificar o papel secundário do jornalismo cultural em relação a outras editorias, quanto entender as novas possibilidades de busca e uso de conteúdos que estão ao nosso alcance no ambiente digital. / The constant use of streaming platforms to access the most diverse content is a reality. Given this framework, we can also see these platforms assuming functions in this digital environment which were previously performed by traditional means of communication. One of these functions we can consider is music curatorship. The objective of this master's thesis is to propose an investigation and immersion in the musical streaming platform, Spotify, and to analyze how it operates to disseminate its musical contents, thus creating through its curatorial strategies a notion of a new cultural journalism. The bibliographies triggered include cultural convergence, cultural journalism, hypermedia radiojournalism and curation, as well as a questionnaire on habits of new patterns of music consumption followed by the respective analysis. Thus, this work seeks to contribute both to demystify the secondary role of cultural journalism in relation to other publications, and to understand the new possibilities of search and use of contents that are within our reach in the digital environment.

Made available in DSpace on 2016-04-26T18:18:03Z (GMT). No. of bitstreams: 1 Johan Cavalcanti van Haandel.pdf: 1998712 bytes, checksum: 208cad61d2ab422d9484c67e1d70027c (MD5) Previous issue date: 2009-05-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In the last years the transmission of audio is being transformed for the new technologies of the digital support, which had generated new processes and products, among them is the sonorous webcasting. This work investigates the creation of content of the four existing formats of sonorous webcasting: web radio, playlist, on demand audio and the audio portal, which comprises the corpus of the research. As methodological strategy, firstly, examples of the sonorous webcasting formats and of others transmission processes for the digital support had been observed, to distinguish them; the second step was to observe the assembly of audio of the sonorous webcasting formats and the third step was to investigate its graphical interfaces. With basis in the methodological strategy, the research presents itself in three stages: in the first one, it was outlined a mapping of the existing digital transmissions of audio and a classification of sonorous webcasting formats, in which the main authors of reference are Trigo-De-Souza and Kischinhevsky, among others; in the second stage, the construction of the transmission of sonorous webcasting through audio assembly is investigated with data based on Ferraretto, Cyro César, Barbosa Filho and McLeish, among others; and in third stage, it is investigated the construction of the transmission of sonorous webcasting through the graphical interface, where the hypermedia interfaces study referring data are based on Beiguelman, Manovich and Johnson. It is concluded that sonorous webcasting consists of a transmission process of audio that does not have to be confounded with radio and it sets up a new type of content reading, mediated by texts and images, implying, therefore, in studies of audio assembly and graphical interface / Nos últimos anos a transmissão de áudio está sendo transformada pelas novas tecnologias do suporte digital, as quais geraram novos processos e produtos, entre eles o webcasting sonoro. A presente pesquisa investiga a criação de conteúdo dos quatro formatos existentes do webcasting sonoro: a web rádio, a playlist, o áudio on demand e o portal de áudio, os quais compõem o corpus da pesquisa. Como estratégia metodológica, primeiro foram observados exemplos dos formatos do webcasting sonoro e de outros processos de transmissão pelo suporte digital, para particularizá-los; o segundo passo foi observar a montagem de áudio dos formatos do webcasting sonoro e o terceiro passo foi investigar as suas interfaces gráficas. Baseada na estratégia metodológica, a pesquisa se apresenta em três etapas: na primeira, há um mapeamento das transmissões digitais de áudio existentes e uma classificação dos formatos do webcasting sonoro, em que os principais autores de referência são Trigo-De-Souza e Kischinhevsky, entre outros; na segunda, é investigada a construção da transmissão do webcasting sonoro através da montagem de áudio, com dados baseados em Ferraretto, Cyro César, Barbosa Filho e McLeish, entre outros; e na terceira, é investigada a construção da transmissão do webcasting sonoro através da interface gráfica, em que os dados referentes ao estudo de interfaces da hipermídia são baseados em Beiguelman, Manovich e Johnson. Conclui-se que o webcasting sonoro consiste em um processo de transmissão de áudio que não deve ser confundido com rádio e que institui um novo tipo de leitura de conteúdo, mediado por textos e imagens, implicando, por isso, em estudos de montagem sonora e de interface gráfica

Cette thèse traite de la modélisation et la diffusion de grandes scènes 3D naturelles. Nous visons à fournir des techniques pour permettre à des utilisateurs de naviguer à distance dans une scène 3D naturelle, tout en assurant la cohérence botanique et l'interactivité. Tout d'abord, nous fournissons une technique de compression multi-résolution, fondée sur la normalisation, l'instanciation, la décorrélation, et sur le codage entropique des informations géometriques pour des modèles de plantes. Ensuite, nous étudions la transmission efficace de ces objets 3D. L'algorithme de paquétisation proposé fonctionne pour la plupart des représentations multi-résolution d'objet 3D. Nous validons les techniques de paquétisation par des expériences sur un WAN (Wide Area Network), avec et sans contrôle de congestion (Datagram Congestion Control Protocol). Enfin, nous abordons les questions du streaming au niveau de la scène. Nous optimisons le traitement des requêtes du côté serveur en fournissant une structure de données adaptée et nous préparons le terrain pour nos travaux futurs sur l'évolutivité et le déploiement de systèmes distribués de streaming 3D. / This thesis deals with the modeling and the interactive streaming of large natural 3D scenes. We aim at providing techniques to allow the remote walkthrough of users in a natural 3D scene ensuring botanical coherency and interactivity.First, we provide a compact and progressive representation for botanically realistic plant models. The topological structure and the geometry of the plants are represented by generalized cylinders. We provide a multi-resolution compression scheme, based on standardization and instantiation, on difference-based decorrelation, and on entropy coding. Then, we study efficient transmission of these 3D objects. The proposed packetization scheme works for any multi-resolution 3D representation. We validate our packetization schemes with extensive experiments over a WAN (Wide Area Network), with and without congestion control (Datagram Congestion Control Protocol). Finally, we address issues on streaming at the scene-level. We optimize the viewpoint culling requests on server-side by providing an adapted datastructure and we prepare the ground for our further work on scalability and deployment of distributed 3D streaming systems.