Essay/Term paper: Another virtual reality

Essay, term paper, research paper:  Medicine

Imagine being able to point into the sky and fly. Or
perhaps walk through space and connect
molecules together. These are some of the dreams
that have come with the invention of virtual reality.
With the introduction of computers, numerous
applications have been enhanced or created. The
newest technology that is being tapped is that of
artificial reality, or "virtual reality" (VR). When
Morton Heilig first got a patent for his "Sensorama
Simulator" in 1962, he had no idea that 30 years
later people would still be trying to simulate reality
and that they would be doing it so effectively.
Jaron Lanier first coined the phrase "virtual reality"
around 1989, and it has stuck ever since.
Unfortunately, this catchy name has caused people
to dream up incredible uses for this technology
including using it as a sort of drug. This became
evident when, among other people, Timothy Leary
became interested in VR. This has also worried
some of the researchers who are trying to create
very real applications for medical, space, physical,
chemical, and entertainment uses among other
things. In order to create this alternate reality,
however, you need to find ways to create the
illusion of reality with a piece of machinery known
as the computer. This is done with several
computer-user interfaces used to simulate the
senses. Among these, are stereoscopic glasses to
make the simulated world look real, a 3D auditory
display to give depth to sound, sensor lined gloves
to simulate tactile feedback, and head-trackers to
follow the orientation of the head. Since the
technology is fairly young, these interfaces have
not been perfected, making for a somewhat
cartoonish simulated reality. Stereoscopic vision is
probably the most important feature of VR
because in real life, people rely mainly on vision to
get places and do things. The eyes are
approximately 6.5 centimeters apart, and allow
you to have a full-colour, three-dimensional view
of the world. Stereoscopy, in itself, is not a very
new idea, but the new twist is trying to generate
completely new images in real- time. In 1933, Sir
Charles Wheatstone invented the first stereoscope
with the same basic principle being used in today's
head-mounted displays. Presenting different views
to each eye gives the illusion of three dimensions.
The glasses that are used today work by using
what is called an "electronic shutter". The lenses of
the glasses interleave the left-eye and right-eye
views every thirtieth of a second. The shutters
selectively block and admit views of the screen in
sync with the interleaving, allowing the proper
views to go into each eye. The problem with this
method though is that you have to wear special
glasses. Most VR researchers use complicated
headsets, but it is possible to create stereoscopic
three-dimensional images without them. One such
way is through the use of lenticular lenses. These
lenses, known since Herman Ives experimented
with them in 1930, allow one to take two images,
cut them into thin vertical slices and interleave
them in precise order (also called multiplexing) and
put cylinder shaped lenses in front of them so that
when you look into them directly, the images
correspond with each eye. This illusion of depth is
based on what is called binocular parallax.
Another problem that is solved is that which
occurs when one turns their head. Nearby objects
appear to move more than distant objects. This is
called motion parallax. Lenticular screens can
show users the proper stereo images when moving
their heads well when a head- motion sensor is
used to adjust the effect. Sound is another
important part of daily life, and thus must be
simulated well in order to create artificial reality.
Many scientists including Dr. Elizabeth Wenzel, a
researcher at NASA, are convinced the 3D audio
will be useful for scientific visualization and space
applications in the ways the 3D video is somewhat
limited. She has come up with an interesting use
for virtual sound that would allow an astronaut to
hear the state of their oxygen, or have an
acoustical beacon that directs one to a trouble
spot on a satellite. The "Convolvotron" is one such
device that simulates the location of up to four
audio channels with a sort of imaginary sphere
surrounding the listener. This device takes into
account that each person has specialized auditory
signal processing, and personalizes what each
person hears. Using a position sensor from
Polhemus, another VR research company, it is
possible to move the position of sound by simply
moving a small cube around in your hand. The key
to the Convolvotron is something called the
"Head- Related Transfer Function (HRTF)",
which is a set of mathematically modelable
responses that our ears impose on the signals they
get from the air. In order to develop the HRTF,
researchers had to sit people in an anechoic room
surrounded with 144 different speakers to
measure the effects of hearing precise sounds from
every direction by using tiny microphone probes
placed near the eardrums of the listener. The way
in which those microphones distorted the sound
from all directions was a specific model of the way
that person's ears impose a complex signal on
incoming sound waves in order to encode it in
their spatial environment. The map of the results is
then converted to numbers and a computer
performs about 300 million operations per second
(MIPS) to create a numerical model based on the
HRTF which makes it possible to reconfigure any
sound source so that it appears to be coming from
any number of different points within the acoustic
sphere. This portion of a VR system can really
enhance the visual and tactile responses. Imagine
hearing the sound of footsteps behind you in a
dark alley late at night. That is how important 3D
sound really is. The third important sense that we
use in everyday life is that of touch. There is no
way of avoiding the feeling of touch, and thus this
is one of the technologies that is being researched
upon most feverishly. The two main types of
feedback that are being researched are that of
force- reflection feedback and tactile feedback.
Force feedback devices exert a force against the
user when they try to push something in a virtual
world that is 'heavy'. Tactile feedback is the
sensation of feeling an object such as the texture of
sandpaper. Both are equally important in the
development of VR. Currently, the most
successful development in force- reflective
feedback is that of the Argonne Remote
Manipulator (ARM). It consists of a group of
articulated joints, encoiled by long bunches of
electrical cables. The ARM allows for six degrees
of movement (position and orientation) to give a
true feel of movement. Suspended from the ceiling
and connected by a wire to the computer, this
machine grants a user the power to reach out and
manipulate 3D objects that are not real. As is the
case at the University of North Carolina, it is
possible to "dock molecules" using VR. Simulating
molecular forces and translating them into physical
forces allows the ARM to push back at the user if
he tries to dock the molecules incorrectly. Tactile
feedback is just as important as force feedback in
allowing the user to "feel" computer-generated
objects. There are several methods for providing
tactile feedback. Some of these include inflating air
bladders in a glove, arrays of tiny pins moved by
shape memory wires, and even fingertip
piezoelectric vibrotactile actuators. The latter
method uses tiny crystals that vibrate when an
electric current stimulates them. This design has
not really taken off however, but the other two
methods are being more actively researched.
According to a report called "Tactile Sensing in
Humans and Robots," distortions inside the skins
cause mechanosensitive nerve terminals to
respond with electrical impulses. Each impulse is
approximately 50 to 100mV in magnitude and 1
ms in duration. However, the frequency of the
impulses (up to a maximum of 500/s) depends on
the intensity of the combination of the stresses in
the area near the receptor which is responsive. In
other words, the sensors which affect pressure in
the skin are all basically the same, but can convey
a message over and over to give the feeling of
pressure. Therefore, in order to have any kind of
tactile response system, there must be a frequency
of about 500 Hz in order to simulate the tactile
accuracy of the human. Right now however, the
gloves being used are used as input devices. One
such device is that called the DataGlove. This
well-fitting glove has bundles of optic fibers
attached at the knuckles and joints. Light is passed
through these optic fibers at one end of the glove.
When a finger is bent, the fibers also bend, and the
amount of light that is allowed through the fiber
can be converted to determine the location at
which the user is. The type of glove that is wanted
is one that can be used as an input and output
device. Jim Hennequin has worked on an "Air
Muscle" that inflates and deflates parts of a glove
to allow the feeling of various kinds of pressure.
Unfortunately at this time, the feel it creates is
somewhat crude. The company TiNi is exploring
the possibility of using "shape memory alloys" to
create tactile response devices. TiNi uses an alloy
called nitinol as the basis for a small grid of what
look like ballpoint-pen tips. Nitinol can take the
shape of whatever it is cast in, and can be
reshaped. Then when it is electrically stimulated,
the alloy it can return to its original cast shape. The
hope is that in the future some of these techniques
will be used to form a complete body suit that can
simulate tactile sensation. Being able to determine
where in the virtual world means you need to have
orientation and position trackers to follow the
movements of the head and other parts of the
body that are interfacing with the computer. Many
companies have developed successful methods of
allowing six degrees of freedom including
Polhemus Research, and Shooting Star
Technology. Six degrees of freedom refers to a
combination cartesian coordinate system and an
orientation system with rotation angles called roll,
pitch and yaw. The ADL-1 from Shooting Star is
a sophisticated and inexpensive (relative to other
trackers) 6D tracking system which is mounted on
the head, and converts position and orientation
information into a readable form for the computer.
The machine calculates head/object position by
the use of a lightweight, multiply-jointed arm.
Sensors mounted on this arm measure the angles
of the joints. The computer-based control unit
uses these angles to compute position-orientation
information so that the user can manipulate a
virtual world. The joint angle transducers use
conductive plastic potentiometers and ball
bearings so that this machine is heavy duty.
Time-lag is eliminated by the direct-reading
transducers and high speed microprocessor,
allowing for a maximum update rate of
approximately 300 measurements/second.
Another system developed by Ascension
Technology does basically the same thing as the
ADL-1, but the sensor is in the form of a small
cube which can fit in the users hand or in a
computer mouse specially developed to encase it.
The Ascension Bird is the first system that
generates and senses DC magnetic fields. The
Ascension Bird first measures the earth's magnetic
field and then the steady magnetic field generated
by the transmitter. The earth's field is then
subtracted from the total, which allows one to
yield true position and orientation measurements.
The existing electromagnetic systems transmit a
rapidly varying AC field. As this field varies, eddy
currents are induced in nearby metals which
causes the metals to become electromagnets
which distort the measurements. The Ascension
Bird uses a steady DC magnetic filed which does
not create an eddy current. The update rate of the
Bird is 100 measurements/second. However, the
Bird has a small lag of about 1/60th of a second
which is noticeable. Researchers have also thought
about supporting the other senses such as taste
and smell, but have decided that it is unfeasible to
do. Smell would be possible, and would enhance
reality, but there is a certain problem with the fact
that there is only a limited spectrum of smells that
could be simulated. Taste is basically a disgusting
premise from most standpoints. It might be useful
for entertainment purposes, but has almost no
purpose for researchers or developers. For one
thing, people would have to put some kind of
receptors in their mouths and it would be very
unsanitary. Thus, the main senses that are relied on
in a virtual reality are sight, touch, and hearing.
Applications of Virtual Reality Virtual Reality has
promise for nearly every industry ranging from
architecture and design to movies and
entertainment, but the real industry to gain from
this technology is science, in general. The money
that can be saved examining the feasibility of
experiments in an artificial world before they are
done could be great, and the money saved on
energy used to operate such things as wind tunnels
quite large. The best example of how VR can help
science is that of the "molecular docking"
experiments being done in Chapel Hill, North
Carolina. Scientists at the University of North
Carolina have developed a system that simulated
the bonding of molecules. But instead of using
complicated formulas to determine bonding
energy, or illegible stick drawings, the potential
chemist can don a high-tech head-mounted
display, attach themselves to an artificial arm from
the ceiling and actually push the molecules together
to determine whether or not they can be
connected. The chemical bonding process takes
on a sort of puzzle-like quality, in which even
children could learn to form bonds using a trial and
error method. Architectural designers have also
found that VR can be useful in visualizing what
their buildings will look like when they are put
together. Often, using a 2D diagram to represent a
3D home is confusing, and the people that fund
large projects would like to be able to see what
they are paying for before it is constructed. An
example which is fascinating would be that of
designing an elementary school. Designers could
walk in the school from a child's perspective to
gain insight on how high that water fountain is, or
how narrow the halls are. Product designers could
also use VR in similar ways to test their products.
NASA and other aerospace facilities are
concentrating research on such things as human
factors engineering, virtual prototyping of buildings
and military devices, aerodynamic analysis, flight
simulation, 3D data visualization, satellite position
fixing, and planetary exploration simulations. Such
things as virtual wind tunnels have been in
development for a couple years and could save
money and energy for aerospace companies.
Medical researchers have been using VR
techniques to synthesize diagnostic images of a
patient's body to do "predictive" modeling of
radiation treatment using images created by
ultrasound, magnetic resonance imaging, and X-
ray. A radiation therapist in a virtual would could
view and expose a tumour at any angle and then
model specific doses and configurations of
radiation beams to aim at the tumour more
effectively. Since radiation destroys human tissue
easily, there is no allowance for error. Also,
doctors could use "virtual cadavers" to practice
rare operations which are tough to perform. This is
an excellent use because one could perform the
operation over and over without the worry of
hurting any human life. However, this sort of
practice may have it's limitations because of the
fact that it is only a virtual world. As well, at this
time, the computer-user interfaces are not well
enough developed and it is estimated that it will
take 5 to 10 years to develop this technology. In
Japan, a company called Matsushita Electric
World Ltd. is using VR to sell their products. They
employ a VPL Research head-mounted display
linked to a high-powered computer to help
prospective customers design their own kitchens.
Being able to see what your kitchen will look like
before you actually refurnish could help you save
from costly mistakes in the future. The
entertainment industry stands to gain a lot from
VR. With the video game revolution of bigger and
better games coming out all the time, this could be
the biggest breakthrough ever. It would be
fantastic to have sword fights which actually feel
real. As well, virtual movies (also called vroomies)
are being developed with allow the viewer to
interact with the characters in the movie. Universal
Studios among others is developing a virtual reality
amusement park which will incorporate these
games and vroomies. As it stands, almost every
industry has something to gain from VR and in the
years to comes, it appears that the possibilities are
endless. The Future of Virtual Reality In the
coming years, as more research is done we are
bound to see VR become as mainstay in our
homes and at work. As the computers become
faster, they will be able to create more realistic
graphic images to simulate reality better. As well,
new interfaces will be developed which will
simulate force and tactile feedback more
effectively to enhance artificial reality that much
more. This is the birth of a new technology and it
will be interesting to see how it develops in the
years to come. However, it may take longer than
people think for it to come into the mainstream.
Millions of dollars in research must be done, and
only select industries can afford to pay for this.
Hopefully, it will be sooner than later though. It is
very possible that in the future we will be
communicating with virtual phones. Nippon
Telephone and Telegraph (NTT) in Japan is
developing a system which will allow one person
to see a 3D image of the other using VR
techniques. In the future, it is conceivable that
businessmen may hold conferences in a virtual
meeting hall when they are actually at each ends of
the world. NTT is developing a new method of
telephone transmission using fiber optics which will
allow for much larger amounts of information to be
passed through the phone lines. This system is
called the Integrated Services Digital Network
(ISDN) which will help allow VR to be used in
conjunction with other communication methods.
Right now, it is very expensive to purchase, with
the head-mounted display costing anywhere from
about $20,000 to $1,000,000 for NASA's Super
Cockpit. In the future, VR will be available to the
end-user at home for under $1000 and will be of
better quality than that being developed today.
The support for it will be about as good as it is
currently for plain computers, and it is possible
that VR could become a very useful teaching tool.
Sources of Information Books and Periodicals
Benningfield, Damond. "The Virtues of Virtual
Reality." Star Date, July/Aug. 1991, pp. 14-15.
Burrill, William. "Virtual Reality." Toronto Star, 13
July 1991, pp. J1-3. Brill, Louis M. "Facing
Interface Issues." Computer Graphics World,
April 1992, pp. 48-58. Daviss, Bennett. "Grand
Illusions." Discover, June 1990, pp. 36-41.
Emmett, Arielle. "Down to Earth: Practical
Applications of Virtual Reality Find Commercial
Uses." Computer Graphics World, March 1992,
pp. 46-54. Peterson, Ivars. "Recipes for Artificial
Realities." Science News, 24 Nov. 1990, pp.
328-329. Peterson, Ivars. "Looking-Glass
Worlds." Science News, 4 Jan 1992, pp. 8-15.
Porter, Stephen. "Virtual Reality." Computer
Graphics World, March 1992, pp. 42-43.
Rheingold, Howard. Virtual Reality. Toronto:
Summit Books, 1991. Tisdale, Sallie. "It's Been
Real." Esquire, April 1991, pp. 36-40. Various.
Virtual Reality Special Report. San Francisco:
Meckler Publishing, 1992. Companies Contacted:
Ascension Technology Corp. P.O Box 527
Burlington, VT 05402 (802)655-7879 Polhemus
Inc. P.O Box 560 Colchester, VT 05446
(802)655-3159 Shooting Star Technology 1921
Holdom Ave. Burnaby, BC V5B 3W4
(604)298-8574 Virtual Technologies P.O. Box
5984 Stanford, CA 94309 (415)599-2331 VPL
Research Inc. 656 Bair Island Rd. Third Floor
Redwood City, CA 94063 (415)361-1710