Varakliotis, Socrates; (2004) QoS-enabled streaming of animated 3-D wireframe models. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

The rapid growth of end systems processing power and the development of state-of-the-art animation modelling packages gave birth to the field of animated 3-D graphics. However, the considerable amount of data involved in 3-D animations, combined with lack of inherent QoS support in the best-effort Internet, has meant that 3-D animation is, at best, still an emerging network stream type. Indeed, it is currently going through the early stages of the same development process undergone by what are now regarded as 'traditional' multimedia stream types in the 1990s. Naivety in the transmission of 3-D streams means that the network is exposed to a risk of considerably increased congestion, along with serious concerns about possible effects on existing well-behaved bulk data, or legacy audiovisual streaming media traffic, for which a largely acceptable degree of QoS has been achieved over the last decade. In order for networked animation to become a reality, it is necessary (i) to encode 3-D animation streams in a way that is compact, (ii) to ensure that congestive loss suffered on the network has as little perceptual impact as possible and, (iii) to ensure that the overall perceptual quality of the animation remains acceptable in the presence of fluctuating bandwidth. We present solutions to each part. In order to ground the individual pieces of practical work that we have undertaken within an appropriate context, we propose and evaluate an end-to-end architecture suitable for streaming the novel data type of 3-D wireframe animations over the Internet. We then explain how we instantiate this architecture in order to (i) allow the representation of time evolving 3-D geometry data at the source in a single resolution stream, (ii) achieve high animation quality by maintaining optimal error control over the model's surface smoothness by adding appropriate redundancy and, (iii) demonstrate Internet-friendly behaviour by finely adjusting the encoded animation rate at the source, thus gracefully adapting to a 3-D model quality corresponding to the available channel bandwidth. The rate controller operates in tandem with a source coding mechanism based on 3-D mesh decimation principles, which trades quality by reducing the number of geometric constructs encoded in the bitstream. The decimated geometric constructs are further predicted by their neighbours in an appropriately designed receiver, which is also capable of recovering from limited frame losses.

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