|
Virtual
Reality
 Eidetics
Corporation has been involved in the application of Virtual Reality to aircraft
simulation since 1992. Through the US Air Force Research Labs Small Business
Innovative Research program called Virtual Reality for Close-In-Combat
and internal research and development, Eidetics has developed a state-of-the-art
Virtual Reality Air Combat Simulator (ViRACS). This system was delivered to Wright
Patterson Air Force Base in April 1997.
Background
In
all simulation of manned vehicles, high quality visual feedback to the pilot is
one of the most important elements required to provide full immersion in the
training environment. In air combat simulation the visual display is
particularly critical because a pilot's life depends upon what they can or
cannot see. Moreover, pilots tend to have excellent vision, often better than
20/20. The visual system must provide high resolution and a wide field of
regard. The importance of the visual system for aircraft simulation, as a
result, has fostered several new technologies:
In
the past, the preferred presentation of 360° field-of-view computer generated
imagery has been a dome system. Domes come in many shapes and sizes. There are
spherical domes and regular polyhedral based systems. There are domes with
external projectors, internal projectors, and combinations thereof. Never the
less, all domes share the feature that the display surface is independent of the
users head position.
The
major limitation of a dome system is the cost of providing sufficient display
resolution over the entire dome. The cost of covering a dome with high
resolution (eye limited) images can be reduced by utilizing area-of-interest
projectors. In this arrangement a low resolution background image is projected
over the whole dome and a high resolution inset is projected where the pilot is
looking by tracking either the head or eye position. This approach remains cost
effective as long as the cost of a slaved projector is less than the cost of
additional image generators and fixed projectors.
Head
Mounted Displays
Another
approach that has become practical, is providing a 360° field of view in a
head-mounted display. In the typical HMD configuration, the display is attached
to the viewer's head so that he sees computer imagery no matter where he looks.
The field of view of an HMD is typically quoted as the instantaneous field of
view, since the total field of view is limited only by the users' head motion. A
head tracker, typically mechanical or magnetic, is used to determine the correct
eye point and orientation to draw the imagery in the HMD. Head-mounted systems
therefore have the advantage of an area of interest projector, since they only
provide high resolution imagery where the viewer is looking, at a substantially
lower price.
The
inherent benefits of a head-mounted approach are that it does not require large
facilities, and it will tend to have lower costs for computer generated imagery.
The principle detriments of a head-mounted approach are size, weight and
balance. However, given the historical trends in electronics toward
miniaturization we can expect these features to improve rapidly over time. Work
is already underway to draw imagery directly into the users' eyes, and perhaps
further in the future, research is progressing toward being able to stimulate
the optic nerves electrically. It may be many years before this technology
becomes available and affordable, but systems that are available today do
provide high resolution, wide field of view displays with weights on the order
of 4 pounds which has proven to be quite useable.
ViRACS
Eidetics'
Virtual Reality Air Combat Simulator (ViRACS) utilizes
an n-Vision DataVisor 80 HMD and a Silicon
Graphics InfiniteReality Image Generator. The DataVisor
80 provides a full color, high resolution (1280 x 1024 pixels), wide
field-of-view (120 x 60 degrees) stereo display to the pilot. The DataVisor 80
represents a great leap forward in capability for HMDs at a reasonable price. A
partially immersive environment has been selected where the pilot is able to
utilize glass cockpit gages that project through a computer generated cockpit
mask in the HMD. The mask position is updated with head position as measured by
a magnetic head tracking unit.
ViRACS
also includes a full sized, fiberglass cockpit shell with a high fidelity, hands
on stick and throttle control set and glass cockpit instrumentation. This system
also has a sound system and a HMD repeater monitor.
Eidetics'
ViRACS station may be integrated into different aircraft environments as
necessary. Currently, Wright Patterson is using their station with Boeing's MIL-AASPEM
II combat analysis tool to provide the aircraft and avionics math modeling.
Eidetics uses the ViRACS system in conjunction with the ARENA
full aircraft simulator. ViRACS is designed with a clean interface so that
it may be integrated with many different simulations. |
