92.03.12
========

From: d3g450@dsom_sup.pnl.gov
Subject: CULTURE: Lawnmower Man - Again.
Date: Thu, 12 Mar 1992 18:33:27 GMT
Organization: Battelle Pacific Northwest Labs, Richland, WA



Hey All...

   I guess I have to go against the flow on this. I really liked the movie,
but I wasn't judging from the acting, the "evil agency" or the silly plot line.
I was more interested in seeing how the movies are portraying the potential
of VR. As a User Interface specialist, getting a glipse at different
technologies and where they may go in 5, 10, 20 years is an interesting
concept. I know, it's only Science fiction, but it did give me some visions
of what VR may be like.

   I figure that in a virtual world, we're dealing with close to 100% interface
issues. Not from a hardware standpoint, but from a software standpoint.
Although I realize that the technology that they were portraying was *way* more
advanced than what is currently available, I don't see why it won't eventually
reach that stage. I'm not talking about the silly mind altering drugs, and
the psychic powers...but the VR worlds they portrayed...

   Maybe I found it interesting because from an interface standpoint it pre-
sents problems beyond what I have previously considered. How do you deal with
navigation and input in VR worlds? How do you deal with presenting relevant
information as opposed to just noise...etc...

   I give it a thumbs up...not from a technical standpoint, but from a fantasy
standpoint. If anything, it did create some awareness for the technology,
which may or may not be beneficial in the long run...

   Has anyone written any books or papers on interface issues? I'd be
interested in finding out more about this technology and what has or has not
been considered yet...

-Marc

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DISCLAIMER: Any opinions are my own...
-----------------------------------------  *************** *** ***************
Marc Pottier                                 ************* **  *************
Battelle Pacific Northwest Laboratories            *******************
                                                      *************
User Interface Design                                     *****
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d3g450%dsom_sup@pnlg.pnl.gov                               *** 
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From: cs_d476@kingston.ac.uk (Leaback P D)
Subject: Re: TECH: of costs and Convolvotrons.
Date: Thu, 12 Mar 1992 19:11:49 GMT
Organization: Kingston Polytechnic



>Here's a reference for a system that did all this with even less:
>no pinnea delay lines, just lowpass filters.  Subjects easily
>"found" a virtual sound source in a large room, to an error of
>15 cm!  Of course, head tracking was used.

I think you are being (unintentionally) slightly misleading. The paper
you give a reference to concerns itself with seeking out a virtual sound
source. Being able to seek a sound source is not a good test of the
ability to simulate localisation cues. For example, varying the volume of
sound presented over a single earphone is sufficient to seek out a
virtual sound source (if coupled with a head tracking device).

I have simulated a filtering process very similar to the one you
described within software and have found that its ability of generating
localisation cues is inferior to even a very small FIR filter. The reason
for this becomes apparent when one analyses what cues are being
presented.

The filter system you describe fails to simulate

        * The frequency dependant interaural time delay function.
        * The frequency dependant head transfer function.
        * The high frequency Pinna filter function.
        * Shoulder bounce.
        * The inverse of the headphone filter function.

A small FIR has a good stab at ALL the localisation cues. I gave up on
the approximation techniques because I came to the conclusion that even
very modest DSP chips can support large enough FIR filters to produce
effects that are more impressive than the approximation techniques could
ever achieve.

However, one advantage of the approximation techniques is that one does
not need access to a Head Related Transfer Function which are not easy to
come by!

Regards,

         Pete Leaback.
         
         .


