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The simulation of a Virtual Environment (VE) is an intensive process which is severely limited if restricted to one machine. Through distribution it is possible to increase the size and accuracy of the simulation, thus permitting multiple users to interact with each other and the VE. Existing distributed VE systems have been designed to target a specific level of distribution. This level is dictated by the geographical distance over which the systems must operate and the communications medium connecting them. The system requirements on a tightly-coupled multiprocessor system are not the same as those of a system operating over a Wide Area Network (WAN). Consequently, the solution for any given level does not scale well to larger or smaller system configurations. VE modelling has its heritage in Computer-Aided Design (CAD) and has evolved unchecked into its present state. As the amount of information required in a VE increases, so the current modelling techniques and tools are put under added stress to cope with the extra load. Most modelling techniques are driven by the structure of the system upon which the model must execute, rather than capturing the structure of the information it should represent. This thesis questions the motives behind VE modelling, examines the problems of distributing a VE and details the various solutions that have been employed. An analysis of the methods used leads to the selection of techniques which may be combined to provide a solution unified over all levels of distribution. The proposed solution is also integrated with and actively supports the modelling process, thus providing a powerful environment for VE designers and participants alike. The architecture of this system is presented complete with a description of a prototype implementation that demonstrates the key aspects. The thesis concludes with an evaluation of the prototype. |
