Monster Media 1993 #2/Image.iso/magazine/aum005.zip/FILE6.005

Text File | 1993-07-16 | 21KB | 375 lines

            Virtual Reality - What it is and How it Works

        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.