The design, implementation, and testing of virtual environments is complicated by the concurrency and real-time features of these systems. Therefore, the development of formal methods for modeling and analysis of virtual environments is highly desirable. In the past, Petri-net models have led to good empirical results in the automatic verification of concurrent and real-time systems. We applied a timed extension of Petri nets to modeling and analysis of the CAVE virtual environment at the University of Illinois at Chicago. Here, we report on our time Petri nets model and on empirical studies that we conducted with the Cabernet toolset from Politenico di Milano. Our experiments uncovered a flaw in the way a shared buffer is used by the CAVE processes. Due to an erroneous synchronization on the buffer, different CAVE walls can simultaneously display images based on different input information. We conclude from our empirical studies that Petri-net-based tools can effectively support the development of reliable virtual environments.

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Mascarenhas, R., Karumuri, D., Buy, U., Kenyon, R., Modeling and Analysis of a Virtual Reality System with Time Petri Nets, Proceedings of the ISEA Conference, Tokyo, Japan, April 20th, 1998.