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5.Levels of VR Hardware Systems


The following defines a number of levels of VR hardware systems. These are not hard levels, especially towards the more advanced systems.

5.1. Entry VR (EVR)


The 'Entry Level' VR system takes a stock personal computer or workstation and implements a WoW system. The system may be based on an IBM clone (MS-DOS/Windows) machine or an Apple Macintosh, or perhaps a Commodore Amiga. The DOS type machines (IBM PC clones) are the most prevalent. There are Mac based systems, but few very fast rendering ones. Whatever the base computer it includes a graphic display, a 2D input device like a mouse, trackball or joystick, the keyboard, hard disk & memory.

5.2. Basic VR (BVR)


The next step up from an EVR system adds some basic interaction and display enhancements. Such enhancements would include a stereographic viewer (LCD Shutter glasses) and a input/control device such as the Mattel PowerGlove and/or a multidimensional (3D or 6D) mouse or joystick.

5.3. Advanced VR (AVR)


The next step up the VR technology ladder is to add a rendering accelerator and/or frame buffer and possibly other parallel processors for input handling, etc. The simplest enhancement in this area is a faster display card. For the PC class machines, there are a number of new fast VGA and SVGA accelerator cards. These can make a dramatic improvement in the rendering performance of a desktop VR system. Other more sophisticated image processors based on the Texas Instruments TI34020 or Intel i860 processor can make even more dramatic improvements in rendering capabilities. The i860 in particular is in many of the high end professional systems. The Silicon Graphics Reality Engine uses a number of i860 processors in addition to the usual SGI workstation hardware to achieve stunning levels of realism in real time animation.

An AVR system might also add a sound card to provide mono, stereo or true 3D audio output. Some sound cards also provide voice recognition. This would be an excellent additional input device for VR applications.

5.4. Immersion VR (IVR)


An Immersion VR system adds some type of immersive display system: a HMD, a Boom, or multiple large projection type displays (Cave).

An IVR system might also add some form of tactile, haptic and touch feedback interaction mechanisms. The area of Touch or Force Feedback (known collectively as Haptics) is a very new research arena.


A common variation on VR is to use a Cockpit or Cab compartment to enclose the user. The virtual world is viewed through some sort of view screen and is usually either projected imagery or a conventional monitor. The cockpit simulation is very well known in aircraft simulators, with a history dating back to the early Link Flight Trainers (1929?). The cockpit is often mounted on a motion platform that can give the illusion of a much larger range of motion. Cabs are also used in driving simulators for ships, trucks, tanks and 'battle mechs'. The latter are fictional walking robotic devices (i.e. the Star Wars films). The BattleTech location based entertainment (LBE) centers use this type of system.

5.5. SIMNET, Defense Simulation Internet


One of the biggest VR projects is the Defense Simulation Internet. This project is a standardization being pushed by the USA Defense Department to enable diverse simulators to be interconnected into a vast network. It is an outgrowth of the Defense Advanced Research Projects Administration (DARPA) SIMNET project of the later 1980s. SIMNET was/is a collection of tank simulators (Cab type) that are networked together to allow unit tactical training. Simulators in Germany can operate in the same virtual world as simulators in the USA, partaking of the same battle exercise.

The basic Distributed Interactive Simulation (DIS) protocol has been defined by the Orlando Institute for Simulation & Training. It is the basis for the next generation of SIMNET, the Defense Simulation Internet (DSI). (love those acronyms!) An accessible, if somewhat dark, treatment of SIMNET and DSI can be found in the premier issue of WIRED magazine (January 1993) entitled "War is Virtual Hell" by Bruce Sterling.

The basic DIS protocol has been adopted as a standard for communication between distributed simulations by the IEEE. Basic information on DIS and SIMNET, including a C library to support the communication protocol is available via FTP from the Internet site taurus.cs.nps.navy.mil (pub/warbreaker/NPS_DIS...). Other contact points for DIS include:

Danette Haworth Institute for Simulation & Training 12424 Research Parkway, Suite 300 Orlando, Florida 32826 (407)658-5000


ModSIM (the language) is available via ftp from max.cecer.army.mil in the isle directory.

ModSAF is being developed to create "Semi-Automated Forces" - both vehicle based and dismounted. There is a body of research and techniques on the various levels of scripting behaviors.

Integrated Simulation (Systems) Language Environment, (ISLE) based on ModSIM with extensions to support Imperative Behavior programming (Prolog-like), and Persistent Objects (ARPA/TI - Open OODB, Open Base, Object Store, etc). Developed by Army Construct Laboratory, Champagne IL Information on ISLE is available via ftp from max.cecer.army.mil in the isle directory.

Integrated Model Development Environment (IMDE) is an iconic, visual programming tool for creating ModSIM programs, uses the Versant ObjectBase (OODBMS). Developed by Armstrong Laboratory

Defense Modeling and Simulation Office (DMSO) has an Internet site to support Advanced Distributed Simulation Technology (ADST). The IP address is 137.249.32.17
Administrative Contact: Kevin Mullally 407.382.4580, Technical Contact: Brad Mohning 408.473.4962


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