A Few Notes on Virtual Reality

1. A Few Notes on Virtual Reality Glenn G. ChappellCHAPPELLG@member.ams.org U. of Alaska Fairbanks CS 381 Lecture Notes Friday, October 17, 2003

2. Notes on VR:Presence • 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. CS 381

3. Notes on VR:How Do We Create “Presence”? • Immersion • Fill the user’s 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 user’s head or eyes, so that we can draw the scene from the correct point of view. • Multisensory Output • Engage as many of the user’s 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”. CS 381

4. Notes on VR:VR 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 don’t trip over things. • Disadvantages  • Cost. • Portability. • Stereoscopic display requires fancy hardware. CS 381

5. Notes on VR:VR Display Types [2/2] • Head-Mounted Display (HMD) • Put one display right in front of each eye, and a tracker somewhere on the user’s 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, HMD’s are the future of VR. However, truly usable HMD’s are not available (yet). When they are, VR can finally go mass-market. CS 381

6. Notes on VR:Other 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! CS 381

7. The remainder of the class meeting was taken up by demonstrations of VR research projects, primarily: • BLUIsculpt (VR sculpting application) • Experimental sound generation CS 381