Implementation of MPEG-4s Subdivision Surfaces Tools

This work is about the implementation of a MPEG-4 decoder for subdivision surfaces, which are powerful 3D paradigms allowing to compactly represent piecewise smooth surfaces. This study will take place in the framework of MPEG-4 AFX, the extension of the MPEG-4 standard including the subdivision surfaces. This document will introduce, with some details, the theory of subdivision surfaces in the two forms present in MPEG-4: plain and detailed/ wavelet subdivision surfaces. It will particularly concentrate on wavelet subdivision surfaces, which permit progressive 3D mesh compression

A model for adapting 3D graphics based on scalable coding, real-time simplification and remote rendering

Most current multiplayer 3D games can only be played on dedicated platforms, requiring specifically designed content and communication over a predefined network. To overcome these limitations, the OLGA (On-Line GAming) consortium has devised a framework to develop distributive, multiplayer 3D games. Scalability at the level of content, platforms and networks is exploited to achieve the best trade-offs between complexity and quality

Representation and coding of 3D video data

Livrable D4.1 du projet ANR PERSEECe rapport a été réalisé dans le cadre du projet ANR PERSEE (n° ANR-09-BLAN-0170). Exactement il correspond au livrable D4.1 du projet

Reliable multimedia transmission over wireless sensor network

Nowadays, video streaming application is widely used in wired as well as wireless environment. Extending this application into Wireless Sensor Networks (WSN) for IEEE 802.15.4 network has attracted lots of attention in the research community. Reliable data transmission is one of the most important requirements in WSN especially for multimedia application. Moreover, multimedia application requires high bandwidth and consumes large memory size in order to send video data that requires small end-to-end (ETE) delay. To overcome this problem, rate control serves as an important technique to control the bit rate of encoded video for transmission over a channel of limited bandwidth and low data rate which is 250kbps with small Maximum Transmission Unit (MTU) size of 127 bytes. Therefore, a rate control model called enhanced Video Motion Classification based (e-ViMoC) model using an optimal combination of parameter setting is proposed in this thesis. Another challenging task to maintain the video quality is the design of an enhanced transport protocol. Standard transport protocols cannot be directly applied in WSN specifically, but some modifications are required. Therefore, to achieve high reliability of video transmission, the advantages of User Datagram Protocol (UDP) features are applied to the proposed transport protocol called Lightweight Reliable Transport Protocol (LRTP) to tailor to the low data rate requirement of WSN. Besides, priority queue scheme is adopted to reduce the end-to-end delay while maintaining the reliability and energy efficiency. Evalvid simulation tool and exhaustive search method are used to determine optimal combination of quantization scale (q), frame rate (r) and Group of Picture (GOP) size (l) values to control the bit rate at the video encoder. The model of e-ViMoC is verified both with simulation and experimental work. The proposed transport protocol has been successfully studied and verified through simulation using Network Simulator 2 (NS-2). From the simulation results, the proposed e-ViMoC encoded video enhances the Packet Delivery Ratio (PDR) by 5.14%, reduces the energy consumed by 16.37%, improves the Peak Signal to Noise Ratio (PSNR) by 4.37% and reduces the ETE delay by 23.69% in average, compared to non-optimized encoded video. The tested experiment experiences slightly different result where the PDR is 6% lower than simulation results. Meanwhile, the combination of e-ViMoC and LRTP outperforms the standard transport protocol by average improvement of 142.9% for PDR, average reduction of 8.87% for energy consumption, average improvement of 4.1% for PSNR, and average reduction of 19.38% for ETE delay. Thus, the simulation results show that the combination of proposed e-ViMoC and LRTP provides better reliability performance in terms of the PDR while simultaneously improves the energy efficiency, the video quality and ETE delay

Network streaming and compression for mixed reality tele-immersion

Bulterman, D.C.A. [Promotor]Cesar, P.S. [Copromotor

Qualitätstaxonomie für skalierbare Algorithmen von Free Viewpoint Video Objekten

Diese Dissertation beabsichtigt einen Beitrag zur Qualitätsbeurteilung von Algorithmen für Bildanalyse und Bildsynthese im Anwendungskontext Videokommunikationssysteme zu leisten. In der vorliegenden Arbeit werden Möglichkeiten und Hindernisse der nutzerzentrierten Definition von subjektiver Qualitätswahrnehmung in diesem speziellen Anwendungsfall untersucht. Qualitätsbeurteilung von aufkommender Visualisierungs-Technologie und neuen Verfahren zur Erzeugung einer dreidimensionalen Repräsentation unter der Nutzung von Bildinformation zweier Kameras für Videokommunikationssysteme wurde bisher noch nicht umfangreich behandelt und passende Ansätze dazu fehlen. Die Herausforderungen sind es qualitätsbeeinflussende Faktoren zu definieren, passende Maße zu formulieren, sowie die Qualitätsevaluierung mit den Erstellungsalgorithmen, welche noch in Entwicklung sind, zu verbinden. Der Vorteil der Verlinkung von Qualitätswahrnehmung und Servicequalität ist die Unterstützung der technischen Realisierungsprozesse hinsichtlich ihrer Anpassungsfähigkeit (z.B. an das vom Nutzer verwendete System) und Skalierbarkeit (z.B. Beachtung eines Aufwands- oder Ressourcenlimits) unter Berücksichtigung des Endnutzers und dessen Qualitätsanforderungen. Die vorliegende Arbeit beschreibt den theoretischen Hintergrund und einen Vorschlag für eine Qualitätstaxonomie als verlinkendes Modell. Diese Arbeit beinhaltet eine Beschreibung des Projektes Skalalgo3d, welches den Rahmen der Anwendung darstellt. Präsentierte Ergebnisse bestehen aus einer systematischen Definition von qualitätsbeeinflussenden Faktoren inklusive eines Forschungsrahmens und Evaluierungsaktivitäten die mehr als 350 Testteilnehmer inkludieren, sowie daraus heraus definierte Qualitätsmerkmale der evaluierten Qualität der visuellen Repräsentation für Videokommunikationsanwendungen. Ein darauf basierendes Modell um diese Ergebnisse mit den technischen Erstellungsschritten zu verlinken wird zum Schluss anhand eines formalisierten Qualitätsmaßes präsentiert. Ein Flussdiagramm und ein Richtungsfeld zur grafischen Annäherung an eine differenzierbare Funktion möglicher Zusammenhänge werden daraufhin für weitere Untersuchungen vorgeschlagen.The thesis intends to make a contribution to the quality assessment of free viewpoint video objects within the context of video communication systems. The current work analyzes opportunities and obstacles, focusing on users' subjective quality of experience in this special case. Quality estimation of emerging free viewpoint video object technology in video communication has not yet been assessed and adequate approaches are missing. The challenges are to define factors that influence quality, to formulate an adequate measure of quality, and to link the quality of experience to the technical realization within an undefined and ever-changing technical realization process. There are two advantages of interlinking the quality of experience with the quality of service: First, it can benefit the technical realization process, in order to allow adaptability (e.g., based on systems used by the end users). Second, it provides an opportunity to support scalability in a user-centered way, e.g., based on a cost or resources limitation. The thesis outlines the theoretical background and introduces a user-centered quality taxonomy in the form of an interlinking model. A description of the related project Skalalgo3d is included, which offered a framework for application. The outlined results consist of a systematic definition of factors that influence quality, including a research framework, and evaluation activities involving more than 350 participants. The thesis includes the presentation of quality features, defined by evaluations of free viewpoint video object quality, for video communication application. Based on these quality features, a model that links these results with the technical creation process, including a formalized quality measure, is presented. Based on this, a flow chart and slope field are proposed. These intend the visualization of these potential relationships and may work as a starting point for further investigations thereon and to differentiate relations in form of functions

Low delay video coding

Analogue wireless cameras have been employed for decades, however they have not become an universal solution due to their difficulties of set up and use. The main problem is the link robustness which mainly depends on the requirement of a line-of-sight view between transmitter and receiver, a working condition not always possible. Despite the use of tracking antenna system such as the Portable Intelligent Tracking Antenna (PITA [1]), if strong multipath fading occurs (e.g. obstacles between transmitter and receiver) the picture rapidly falls apart. Digital wireless cameras based on Orthogonal Frequency Division Multiplexing (OFDM) modulation schemes give a valid solution for the above problem. OFDM offers strong multipath protection due to the insertion of the guard interval; in particular, the OFDM-based DVB-T standard has proven to offer excellent performance for the broadcasting of multimedia streams with bit rates over 10 Mbps in difficult terrestrial propagation channels, for fixed and portable applications. However, in typical conditions, the latency needed to compress/decompress a digital video signal at Standard Definition (SD) resolution is of the order of 15 frames, which corresponds to ≃ 0.5 sec. This delay introduces a serious problem when wireless and wired cameras have to be interfaced. Cabled cameras do not use compression, because the cable which directly links transmitter and receiver does not impose restrictive bandwidth constraints. Therefore, the only latency that affects a cable cameras link system is the on cable propagation delay, almost not significant, when switching between wired and wireless cameras, the residual latency makes it impossible to achieve the audio-video synchronization, with consequent disagreeable effects. A way to solve this problem is to provide a low delay digital processing scheme based on a video coding algorithm which avoids massive intermediate data storage. The analysis of the last MPEG based coding standards puts in evidence a series of problems which limits the real performance of a low delay MPEG coding system. The first effort of this work is to study the MPEG standard to understand its limit from both the coding delay and implementation complexity points of views. This thesis also investigates an alternative solution based on HERMES codec, a proprietary algorithm which is described implemented and evaluated. HERMES achieves better results than MPEG in terms of latency and implementation complexity, at the price of higher compression ratios, which means high output bit rates. The use of HERMES codec together with an enhanced OFDM system [2] leads to a competitive solution for wireless digital professional video applications

Presentation of multiple GEO-referenced videos

Master'sMASTER OF SCIENC

Transform domain texture synthesis on surfaces

In the recent past application areas such as virtual reality experiences, digital cinema and computer gamings have resulted in a renewed interest in advanced research topics in computer graphics. Although many research challenges in computer graphics have been met due to worldwide efforts, many more are yet to be met. Two key challenges which still remain open research problems are, the lack of perfect realism in animated/virtually-created objects when represented in graphical format and the need for the transmissiim/storage/exchange of a massive amount of information in between remote locations, when 3D computer generated objects are used in remote visualisations. These challenges call for further research to be focused in the above directions. Though a significant amount of ideas have been proposed by the international research community in their effort to meet the above challenges, the ideas still suffer from excessive complexity related issues resulting in high processing times and their practical inapplicability when bandwidth constraint transmission mediums are used or when the storage space or computational power of the display device is limited. In the proposed work we investigate the appropriate use of geometric representations of 3D structure (e.g. Bezier surface, NURBS, polygons) and multi-resolution, progressive representation of texture on such surfaces. This joint approach to texture synthesis has not been considered before and has significant potential in resolving current challenges in virtual realism, digital cinema and computer gaming industry. The main focus of the novel approaches that are proposed in this thesis is performing photo-realistic texture synthesis on surfaces. We have provided experimental results and detailed analysis to prove that the proposed algorithms allow fast, progressive building of texture on arbitrarily shaped 3D surfaces. In particular we investigate the above ideas in association with Bezier patch representation of 3D objects, an approach which has not been considered so far by any published world wide research effort, yet has flexibility of utmost practical importance. Further we have discussed the novel application domains that can be served by the inclusion of additional functionality within the proposed algorithms.EThOS - Electronic Theses Online ServiceGBUnited Kingdo