Virtual Reality


Virtual RealityWhat It Is And How It Works Essay, Research Paper

Imagine being able to point into the sky and fly. Orperhaps walk through space and connect molecules together.These are some of the dreams that have come with theinvention of virtual reality. With the introduction ofcomputers, numerous applications have been enhanced orcreated. The newest technology that is being tapped is thatof artificial reality, or “virtual reality” (VR). WhenMorton Heilig first got a patent for his “SensoramaSimulator” in 1962, he had no idea that 30 years laterpeople would still be trying to simulate reality and thatthey would be doing it so effectively. Jaron Lanier firstcoined the phrase “virtual reality” around 1989, and it hasstuck ever since. Unfortunately, this catchy name hascaused people to dream up incredible uses for thistechnology including using it as a sort of drug. This becameevident when, among other people, Timothy Leary becameinterested in VR. This has also worried some of theresearchers who are trying to create very real applicationsfor medical, space, physical, chemical, and entertainmentuses among other things.

In order to create this alternate reality, however, youneed to find ways to create the illusion of reality with apiece of machinery known as the computer. This is done withseveral computer-user interfaces used to simulate thesenses. Among these, are stereoscopic glasses to make thesimulated world look real, a 3D auditory display to givedepth to sound, sensor lined gloves to simulate tactilefeedback, and head-trackers to follow the orientation of thehead. Since the technology is fairly young, theseinterfaces have not been perfected, making for a somewhatcartoonish simulated reality.

Stereoscopic vision is probably the most importantfeature of VR because in real life, people rely mainly onvision to get places and do things. The eyes areapproximately 6.5 centimeters apart, and allow you to have afull-colour, three-dimensional view of the world.Stereoscopy, in itself, is not a very new idea, but the newtwist is trying to generate completely new images in real-time. In 1933, Sir Charles Wheatstone invented the firststereoscope with the same basic principle being used intoday’s head-mounted displays. Presenting different viewsto each eye gives the illusion of three dimensions. Theglasses that are used today work by using what is called an”electronic shutter”. The lenses of the glasses interleave?se of lenticularlenses. These lenses, known since Herman Ives experimentedwith them in 1930, allow one to take two images, cut theminto thin vertical slices and interleave them in preciseorder (also called multiplexing) and put cylinder shapedlenses in front of them so that when you look into themdirectly, the images correspond with each eye. Thisillusion of depth is based on what is called binocularparallax. Another problem that is solved is that whichoccurs when one turns their head. Nearby objects appear tomove more than distant objects. This is called motionparallax. Lenticular screens can show users the properstereo 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 thusmust be simulated well in order to create artificialreality. Many scientists including Dr. Elizabeth Wenzel, aresearcher at NASA, are convinced the 3D audio will beuseful for scientific visualization and space applicationsin the ways the 3D video is somewhat limited. She has comeup with an interesting use for virtual sound that wouldallow an astronaut to hear the state of their oxygen, orhave an acoustical beacon that directs one to a trouble spoton a satellite. The “Convolvotron” is one such device thatsimulates the location of up to four audio channels with asort of imaginary sphere surrounding the listener. Thisdevice takes into account that each person has specializedauditory signal processing, and personalizes what eachperson hears.

Using a position sensor from Polhemus, another VRresearch company, it is possible to move the position ofsound 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 ofmathematically modelable responses that our ears impose onthe signals they get from the air. In order to develop theHRTF, researchers had to sit people in an anechoic roomsurrounded with 144 different speakers to measure theeffects of hearing precise sounds from every direction byusing tiny microphone probes placed near the eardrums of thelistener. The way in which those microphones distorted thesound from all directions was a specific model of the waythat person’s ears impose a complex signal on incoming soundwaves in order to encode it in their spatial environment.?

appears to be coming from any number of different pointswithin the acoustic sphere.

This portion of a VR system can really enhance the visualand tactile responses. Imagine hearing the sound offootsteps behind you in a dark alley late at night. That ishow important 3D sound really is.

The third important sense that we use in everyday life isthat of touch. There is no way of avoiding the feeling oftouch, and thus this is one of the technologies that isbeing researched upon most feverishly. The two main typesof feedback that are being researched are that of force-reflection feedback and tactile feedback. Force feedbackdevices exert a force against the user when they try to pushsomething in a virtual world that is ‘heavy’. Tactilefeedback is the sensation of feeling an object such as thetexture of sandpaper. Both are equally important in thedevelopment of VR.

Currently, the most successful development in force-reflective feedback is that of the Argonne RemoteManipulator (ARM). It consists of a group of articulatedjoints, encoiled by long bunches of electrical cables. TheARM allows for six degrees of movement (position andorientation) to give a true feel of movement. Suspendedfrom the ceiling and connected by a wire to the computer,this machine grants a user the power to reach out andmanipulate 3D objects that are not real. As is the case atthe University of North Carolina, it is possible to “dockmolecules” using VR. Simulating molecular forces andtranslating them into physical forces allows the ARM to pushback at the user if he tries to dock the moleculesincorrectly.

Tactile feedback is just as important as force feedbackin 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 evenfingertip piezoelectric vibrotactile actuators. The lattermethod uses tiny crystals that vibrate when an electriccurrent stimulates them. This design has not really takenoff however, but the other two methods are being moreactively researched. According to a report called “TactileSensing in Humans and Robots,” distortions inside the skinscause mechanosensitive nerve terminals to respond withelectrical impulses. Each impulse is approximately 50 to100mV in magnitude and 1 ms in duration. However, thefrequency of the impulses (up to a maximum of 500/s) depends? which affect pressure in the skin are allbasically the same, but can convey a message over and overto give the feeling of pressure. Therefore, in order tohave any kind of tactile response system, there must be afrequency of about 500 Hz in order to simulate the tactileaccuracy of the human.Right now however, the gloves being used are used asinput devices. One such device is that called theDataGlove. This well-fitting glove has bundles of opticfibers attached at the knuckles and joints. Light is passedthrough these optic fibers at one end of the glove. When afinger is bent, the fibers also bend, and the amount oflight that is allowed through the fiber can be converted todetermine the location at which the user is. The type ofglove that is wanted is one that can be used as an input andoutput device. Jim Hennequin has worked on an “Air Muscle”that inflates and deflates parts of a glove to allow thefeeling of various kinds of pressure. Unfortunately at thistime, the feel it creates is somewhat crude. The companyTiNi is exploring the possibility of using “shape memoryalloys” to create tactile response devices. TiNi uses analloy called nitinol as the basis for a small grid of whatlook like ballpoint-pen tips. Nitinol can take the shape ofwhatever it is cast in, and can be reshaped. Then when itis electrically stimulated, the alloy it can return to itsoriginal cast shape. The hope is that in the future some ofthese techniques will be used to form a complete body suitthat can simulate tactile sensation.

Being able to determine where in the virtual world meansyou need to have orientation and position trackers to followthe movements of the head and other parts of the body thatare interfacing with the computer. Many companies havedeveloped successful methods of allowing six degrees offreedom including Polhemus Research, and Shooting StarTechnology. Six degrees of freedom refers to a combinationcartesian coordinate system and an orientation system withrotation angles called roll, pitch and yaw. The ADL-1 fromShooting Star is a sophisticated and inexpensive (relativeto other trackers) 6D tracking system which is mounted onthe head, and converts position and orientation informationinto a readable form for the computer. The machinecalculates head/object position by the use of a lightweight,multiply-jointed arm. Sensors mounted on this arm measurethe angles of the joints. The computer-based control unituses these angles to compute position-orientationinformation so that the user can manipulate a virtual world.The joint angle transducers use conductive plasticpotentiometers and ball bearings so that this machine isheavy duty. Time-lag is eliminated by the direct-readingtransducers and high speed microprocessor, allowing for amaximum update rate of approximately 300?n nearbymetals which causes the metals to become electromagnetswhich distort the measurements. The Ascension Bird uses asteady DC magnetic filed which does not create an eddycurrent. The update rate of the Bird is 100measurements/second. However, the Bird has a small lag ofabout 1/60th of a second which is noticeable.

Researchers have also thought about supporting the othersenses such as taste and smell, but have decided that it isunfeasible to do. Smell would be possible, and wouldenhance reality, but there is a certain problem with thefact that there is only a limited spectrum of smells thatcould be simulated. Taste is basically a disgusting premisefrom most standpoints. It might be useful for entertainmentpurposes, but has almost no purpose for researchers ordevelopers. For one thing, people would have to put somekind of receptors in their mouths and it would be veryunsanitary. Thus, the main senses that are relied on in avirtual reality are sight, touch, and hearing.

Applications of Virtual RealityVirtual Reality has promise for nearly every industryranging from architecture and design to movies andentertainment, but the real industry to gain from thistechnology is science, in general. The money that can besaved examining the feasibility of experiments in anartificial world before they are done could be great, andthe money saved on energy used to operate such things aswind tunnels quite large.

The best example of how VR can help science is that ofthe “molecular docking” experiments being done in ChapelHill, North Carolina. Scientists at the University of NorthCarolina have developed a system that simulated the bondingof molecules. But instead of using complicated formulas todetermine bonding energy, or illegible stick drawings, thepotential chemist can don a high-tech head-mounted display,attach themselves to an artificial arm from the ceiling and?’sperspective to gain insight on how high that water fountainis, or how narrow the halls are. Product designers couldalso use VR in similar ways to test their products.NASA and other aerospace facilities are concentratingresearch on such things as human factors engineering,virtual prototyping of buildings and military devices,aerodynamic analysis, flight simulation, 3D datavisualization, satellite position fixing, and planetaryexploration simulations. Such things as virtual windtunnels have been in development for a couple years andcould save money and energy for aerospace companies.

Medical researchers have been using VR techniques tosynthesize diagnostic images of a patient’s body to do”predictive” modeling of radiation treatment using imagescreated by ultrasound, magnetic resonance imaging, and X-ray. A radiation therapist in a virtual would could viewand expose a tumour at any angle and then model specificdoses and configurations of radiation beams to aim at thetumour more effectively. Since radiation destroys humantissue easily, there is no allowance for error.Also, doctors could use “virtual cadavers” to practicerare operations which are tough to perform. This is anexcellent use because one could perform the operation overand over without the worry of hurting any human life.However, this sort of practice may have it’s limitationsbecause of the fact that it is only a virtual world. Aswell, at this time, the computer-user interfaces are notwell enough developed and it is estimated that it will take5 to 10 years to develop this technology.

In Japan, a company called Matsushita Electric World using VR to sell their products. They employ a VPLResearch head-mounted display linked to a high-poweredcomputer to help prospective customers design their ownkitchens. Being able to see what your kitchen will looklike before you actually refurnish could help you save fromcostly mistakes in the future.

The entertainment industry stands to gain a lot from VR.?rs that thepossibilities are endless.

The Future of Virtual RealityIn the coming years, as more research is done we arebound to see VR become as mainstay in our homes and at work.As the computers become faster, they will be able to createmore realistic graphic images to simulate reality better.As well, new interfaces will be developed which willsimulate force and tactile feedback more effectively toenhance artificial reality that much more. This is thebirth of a new technology and it will be interesting to seehow it develops in the years to come. However, it may takelonger than people think for it to come into the mainstream.Millions of dollars in research must be done, and onlyselect industries can afford to pay for this. Hopefully, itwill be sooner than later though.

It is very possible that in the future we will becommunicating with virtual phones. Nippon Telephone andTelegraph (NTT) in Japan is developing a system which willallow one person to see a 3D image of the other using VRtechniques. In the future, it is conceivable thatbusinessmen may hold conferences in a virtual meeting hallwhen they are actually at each ends of the world. NTT isdeveloping a new method of telephone transmission usingfiber optics which will allow for much larger amounts ofinformation to be passed through the phone lines. Thissystem is called the Integrated Services Digital Network(ISDN) which will help allow VR to be used in conjunctionwith other communication methods.

Right now, it is very expensive to purchase, with thehead-mounted display costing anywhere from about $20,000 to$1,000,000 for NASA’s Super Cockpit. In the future, VR willbe available to the end-user at home for under $1000 andwill be of better quality than that being developed today.The support for it will be about as good as it is currentlyfor plain computers, and it is possible that VR could becomea very useful teaching tool.

?Discover, June 1990,pp. 36-41.

Emmett, Arielle. “Down to Earth: Practical Applications ofVirtual 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 GraphicsWorld, March 1992, pp. 42-43.?2.

Companies Contacted:

Ascension Technology Corp.P.O Box 527Burlington, VT 05402(802)655-7879

Polhemus Inc.P.O Box 560Colchester, VT 05446(802)655-3159

Shooting Star Technology1921 Holdom Ave.

Burnaby, BC V5B 3W4(604)298-8574

Virtual TechnologiesP.O. Box 5984Stanford, CA 94309(415)599-2331

VPL Research Inc.656 Bair Island Rd. Third FloorRedwood City, CA 94063(415)361-1710

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