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
