Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!lll-winken!elroy.jpl.nasa.gov!sdd.hp.com!zaphod.mps.ohio-state.edu!rpi!dali.cs.montana.edu!milton!autodesk!danr@uunet.UU.NET From: autodesk!danr@uunet.UU.NET (Dan Rosenfeld) Newsgroups: sci.virtual-worlds Subject: Re: We need a new language Message-ID: <15800@milton.u.washington.edu> Date: 4 Feb 91 22:39:07 GMT References: <15594@milton.u.washington.edu> <15638@milton.u.washington.edu> Sender: hlab@milton.u.washington.edu Lines: 61 Approved: cyberoid@milton.u.washington.edu frerichs@ux1.cso.uiuc.edu (David J Frerichs) writes: >In article <15594@milton.u.washington.edu> pete_leaback@cix.compulink.co.uk (Peter Leaback) writes: >[things wiped out] >>A VR system has to display a frame at 50 or 60 Hz or else one tends to >>get sick. If one standardises the object destription and rendering, each >[things abolished] >Your statement that one tends to get sick at a low frame rate is false >(IMHO). Please forgive my forwardness if you have experienced this sickness >first hand. Low frame rates only make for choppy movement, not flickering. >It just means that the frame stays in the buffer longer. When you are >doing computer animation, you don't just flash a picture and take it >away, you hold a picture up til the next one is ready. High frame rate >means smoother motion, not less flicker (flicker has to do with the display >hardware frequency). >I think that alot of people in the newsgroup have been making statements >that they think sound good at the time but aren't supported by any facts, >not a good practice if we are to get to the root of some of the problems >that face our industry. If you are going to make wide statements about >tech, do your homework, or make sure you say that this is your opinion, >not a solid fact. I believe there IS some evidence that low frame rates can cause nausea in simulation participants. I can't provide any references to support this, but I knew several Psychologists at NASA (Ames) who claimed that flight simulator subjects tended to get nauseous when imagery was presented at too low a rate. The issue, I believe, is not flicker, but rather the temporary inconsistency between sensory systems that low frame rate can cause. Specifically, you tilt your Polhemus-tracked head, or a flight simulator tilts you, and your vestibular system tells your brain that you are oriented a certain way. Unfortunately, your visual system is computing your head's orientation on the basis of imagery which represents your head's "view" 100ms ago. I have no understanding of why this should cause nausea, and I'm not sure whether anyone else does, but it does seem to. BTW, I have tried three VR systems and never experienced any nausea, but these demos never lasted more than ten minutes at a time. Dan Disclaimer; I don't work on the Cyberspace project, and I am not representing their views. ---------------------------------------------------------------- Dan Rosenfeld danr@autodesk.com ( ) "Enjoy life, eat out more often." S.I. Rykoff o) o) moo -- ----------------------------------------------------------------