From: wrc@mbay.net (william r. cockayne) Subject: Re: TECH: Networked VR under 100ms? Date: Thu, 12 Sep 1996 01:15:54 -0700 Message-ID: Organization: Monterey Bay Internet, Monterey, CA > : Looking through a number of papers on networked VR (Macedonia for eg) > : I find the recurring quote that says the minimum latency for networking > : in VR should be less than 100ms. Of course no body explains why or from > : what results they gathered this statistic. > : Does anyone have a definitive reference with an explanation. > > I think this figure comes from the DIS spec. The latency that can be > tolerated within a VR system is dependent upon the techniques used to > manage simulation computation and data and, of course, the target > application. For example, an "interactive" visualisation may be able > to tolerate greater latency than a flight simulator. This number actually has nothing to do with technical limitations; it is classically the human threshold for noticing change (ie, discrepancies). If something occurs below the 100 ms limit, the human will not notice. If something takes longer than 100 ms to occur, then the use may notice a discrepancy. If you check the papers you mention (ie, NPS ones) they should mention why they use the 100 ms number; they may not. I would love to give you some references right now, but the books I want are at work and the books I have with me don't actually reference where this number comes from. I seem to remember that Card & Newell provide a good explanation of this idea. bill wrc@mbay.net (william r. cockayne)