From: jleigh@bert.eecs.uic.edu (Jason Leigh)
Subject: Re: TECH: Networked VR under 100ms?
Date: 13 Sep 1996 13:14:58 GMT
Message-ID: <51bmoj$dah@news.eecs.uic.edu>
Organization: University of Illinois at Chicago



william r. cockayne (wrc@mbay.net) wrote:


: 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.

Thanks,

I am aware of Card & Newell's work that explains this but keeping the
lag caused by update due to graphics and lag caused by the network
separate, lets say one could have a high graphical update rate of say
60fps but have a network delay of say 1s before the data is
transmitted (I encountered this delay once while at NCSA). Then as
long as the data stream is constant after that, the viewer would never
really know the delay existed unless there were some frame of
reference to compare it with (e.g. an audio cue that comes before the
visual cue).  I think the 100ms sited in NPS refers to the lag
mentioned by Card & Newel where an intermittent delay of > 100ms will
cause in a break in the continuous animation of the object. That would
be the reason to use dead-reckoning.

In any case I got a reply from Mike Macedonia (thank you Mike).

Regards,
Jason

--


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Jason Leigh
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