SIMNET

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SIMNET is a wide area network of the United States military designed for real-time distributed combat simulation.

The Defense Advanced Research Projects Agency (DARPA) saw the need for networked multi-user simulation. Interactive simulation equipment was very expensive, and reproducing training facilities was likewise expensive and time consuming. In the early 1980s, DARPA decided to create a prototype research system to investigate the feasibility of creating a real-time distributed simulator for combat simulation. SIMNET, the resulting application, was to prove both the feasibility and effectiveness of such a project (Pimental and Blau 1994). SIMNET was developed by two small research companies, Perceptronics, Inc. and Bolt, Beranek and Newman (BBN), Inc. Training using actual equipment was extremely expensive and dangerous. Being able to simulate certain combat scenarios, and to have participants remotely located rather than all in one place, was a huge cost reduction and reduced the risk of personal injury (Rheingold 1992). SIMNET was run across the MILNET, the high speed descendant of the ARPANET that remained under military regulation after the rest of ARPANET was merged with NSFNet and the ARPANET was decommissioned (Rheingold 1992).

Since this was a networked simulation, each simulation station needed it’s own display of the shared virtual environment. The display stations themselves were mock-ups of certain tank and aircraft control simulators, and they were configured to simulate actual conditions within the actual combat vehicle. The tank simulators, for example, could accommodate a full four-person crew complement to enhance the effectiveness of the training. The network was designed to support up to several hundred users at once. The fidelity of the simulation was such that it could be used to train for mission scenarios and tactical rehearsals for operations performed during the U.S. actions in Desert Storm in 1992 (Robinett 1994).

The system used the concept of “dead reckoning” to collect the positions of the objects and actors within the simulated environment. Essentially this approach proposes that the current position of an object can be calculated from its previous position and velocity (which is composed of vector and speed elements) (Pimental and Blau 1994). Its use in the Gulf War demonstrates the success of the SIMNET, and its legacy was viewed as proof that realtime interactive networked cooperative virtual simulation is possible for a large user population.

[edit] References

Pimental, K., and Blau, B. (1994). “Teaching Your System To Share.” IEEE computer graphics and applications, 14(1), 60
Rheingold, H. (1992). Virtual reality, Simon & Schuster, New York, N.Y.
Robinett, W. (1994). “Interactivity and Individual Viewpoint in Shard Virtual Worlds: The Big Screen vs. Networked Personal Displays.” Computer Graphics, 28(2), 127
Stone, A. R. (1991). “, ed., MIT Press