System-wide constraints and user preferences in collaborative virtual environments

The availability of inexpensive and powerful graphics cards as well as fast Internet connections make Networked Virtual Environments viable for millions of users and many new applications. It is therefore necessary to cope with the growing heterogeneity that arises from differences in computing power, network speed and users' preferences. We present an architecture that accommodates the heterogeneity mentioned above while allowing a system administrator to define system-wide policies. Policies and users' preferences can be expressed as simple linear equations forming a mathematical model that describes the system as a whole as well as its individual components. When solutions to this model are mapped back to the problem domain, viable solutions that accommodate heterogeneity and system policies are obtained. First, a static solution, based on benchmarks that characterize the performance of a specific machine, is presented. Then a dynamic solution, based on performance statistics collected during the collaborative session is introduced. The results of our experiments with a proof-of-concept system are described.