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Framework for collaboration in networked virtual environments

and contributions Networked virtual environments (net-VEs) are natural extension of single user virtual environments. The network is used to provide the users with the shared sense of space and time. Net-VEs should also enable the participants to be aware of each other, communicate and share eventual modifications of the environment. The design of net-VE comprises many different computing areas, but two of them are the most significant: computer graphics and computer networks. While computer graphics plays immediately visible role, computer networks are hidden in the background doing the necessary but a little bit thankless job. The thesis reflects the multidisciplinary nature of net-VE: the research has been undertaken within the Computer Graphics Group of the Department of Computer Science and Engineering, but the core of the thesis is focused on networking issues, too. The thesis starts with an introduction to the problematic of net-VEs. We briefly overview the history of the field that originated in military and gaming applications in the middle of the 80’s. The first contribution of the thesis is a taxonomy that uses similar approach to OSI/ISO model to categorize net-VE solutions to several layers. The second contribution is pointing out the relation between net-VEs and heterogeneous multi-computer loosely coupled distributed systems. We prove the relation by providing examples of existing net-VE systems based on three fundamental communication means used in distributed systems. The third contribution is our framework for collaboration in net-VE systems that fills the gap we identified in the middleware layer of our taxonomy: General Variables net-VE middleware. It resolves frequently repeating needs of net-VE systems: synchronization of the shared state, awareness of participants, late-joins, mutual exclusion, interest management, and general format of the data. The fourth contribution is description of several systems, aimed at education (DILEWA, Yachts), collaboration (SVRed, eGaLab), social interaction (e-Agora) or multi-purpose (ALTERNE). We demonstrate how these systems benefited from the General Variables framework to prove the wide range of possible uses of the framework.