Despite their attractive properties, networked virtual environments (net-VEs) are notoriously difficult to design, implement and test due to the concurrency, real-time and networking features in these systems. The current practice for net-VE design is basically trial and error, empirical, and totally lacks formal methods. This paper proposes to apply a Petri net formal modeling technique to a net-VE - NICE (Narrative Immersive Constructionist / Collaborative Environment), predict the net-VE performance based on simulation, and improve the net-VE performance. The NICE is essentially a network of collaborative virtual reality systems called the CAVE - (Cave Automatic Virtual Environment). First, we present extended fuzzy-timing Petri net models of both CAVE and NICE. Then, by using these models and Design / CPN as the simulation tool, we have conducted various simulations to study real-time behavior, network effects and performance (latencies and jitters) of NICE. Our simulation results are consistent with experimental data.

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Zhou, Y., Murata, T., DeFanti, T., Zhang, H., Fuzzy-Timing Petri Net Modeling and Simulation of a Networked Virtual Environment - NICE, Institute of Electronics, Information and Communication Engineers (IEICE) Transactions, Fundmentals Special Section on Concurrent Systems Technology, vol 83, no 11, November 1st, 2000.