A Few Notes on Virtual Reality

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A Few Notes on Virtual Reality

• Glenn G. ChappellCHAPPELLG_at_member.ams.org
• U. of Alaska Fairbanks
• CS 381 Lecture Notes
• Friday, October 17, 2003

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Notes on VRPresence

• A typical 2½-D GUI simulates a desktop.
• Users look at pictures of objects reminiscent of
  overlapping sheets of paper.
• Typical 3-D interfaces give the user a picture of
  a 3-D world.
• Games, etc.
• In virtual reality (VR), we want to give users
  the sense that they are inside a
  computer-generated world.
• In VR this is called the sense of presence.

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Notes on VRHow Do We Create Presence?

• Immersion
• Fill the users vision with CG, so that very
  little of the real world can be seen.
• Stereoscopic Perspective
• Produce different perspective views for each eye,
  giving the illusion of depth.
• Head/Eye Tracking
• Track the position orientation of the users
  head or eyes, so that we can draw the scene from
  the correct point of view.
• Multisensory Output
• Engage as many of the users senses as we can, in
  a coordinated, realistic, 3-D manner.
• Plausible Interaction
• Allow the user to interact with the scene, in as
  direct a manner as possible, in a way that feels
  right.

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Notes on VRVR Display Types 1/2

• Two flavors of VR displays Theater
  Head-Mounted.
• Theater
• This is what we have.
• Most modern theater-type VR displays are based on
  the CAVE.
• CAVE CAVE Automatic Virtual Environment.
• See also Plato (The Republic, Book 7).
• Developed at the Electronic Visualization
  Laboratory, at the U. of Illinois Chicago, in
  1992.
• Advantages ?
• Allows for multiple simultaneous users (in a
  limited sense).
• Allows immersion, but can still see the real
  world if you want.
• So you dont trip over things.
• Disadvantages ?
• Cost.
• Portability.
• Stereoscopic display requires fancy hardware.

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Notes on VRVR Display Types 2/2

• Head-Mounted Display (HMD)
• Put one display right in front of each eye, and a
  tracker somewhere on the users head.
• Advantages ?
• Cost.
• Size.
• Disadvantages ?
• Heavy stuff to wear on your head.
• Physical hazards (tripping, etc.).
• Latency problems! ???
• Latency time to update the display.
• What happens when you move your head and the
  display update is slow? Contrast this with
  theater-type VR.
• In my opinion, HMDs are the future of VR.
  However, truly usable HMDs are not available
  (yet). When they are, VR can finally go
  mass-market.

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Notes on VROther Stuff

• We know how to handle sight and hearing. But what
  about
• Balance
• Tilt the theater. Simple, but bulky expensive.
  Done in flight simulators.
• Touch
• Haptic interfaces are those that involve touch.
• Possible on a small scale (desktop?), but not a
  large scale (Discovery Lab).
• Smell? Taste???
• Forget it (for now).
• Augmented Reality
• Real world CG additions.
• HMD without the tripping problem?
• The Focus Problem
• In VR displays, near far objects are drawn on
  the same screen.
• Objects appear to be at varying distances, but
  the eye always focuses at the same distance.
• Result headaches.
• Go solve this problem!

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• The remainder of the class meeting was taken up
  by demonstrations of VR research projects,
  primarily
• BLUIsculpt (VR sculpting application)
• Experimental sound generation