HDTenEightyP/NetNews huggingface dataset:
From: daver%sunspot.ssl.Berkeley.EDU@ucbvax.Berkeley.EDU (David Ray)
Subject: Re: TECH:  Alternative Head Trackers
Originator: hlab@milton.u.washington.edu
Organization: University of Washington
Date: Fri, 21 Aug 1992 21:20:35 GMT



In article <1992Aug21.194614.21349@u.washington.edu>
clarke@acme.ucf.edu (Thomas Clarke) writes:

>Does anyone know of (rumors of?) headtracking devices that avoid the 1
>meter cube limitations of Polhemus, Logitech and similar units?
>I am especially interested in systems that don't require a room to be
>specially prepared like the UNC optical system.

You might want to check out the sci.virtual-worlds archives, I believe
the "commercial" section has some info on different head-trackers.
They generally use one of 4 methods -- magnetometer, inertia,
ultrasonics/radio, optical.  The ultrasonics and optical types
physically transmit to a reciever, so the head position is limited to
the signal's range and resolution.  The magnetometer and inertia type
head trackers *in principle* should not be restricted since the
sensing mechanism is self-contained. In general the HMD's that use
these are VERY expensive.

I have been researching and planning to build a "low-cost" HMD that
uses magnetometer or inertial sensing to transmit a mouse-type signal
to a Mac ADB and/or a PC's mouse port. The idea is to just substitute
the HMD for the mouse in order to simplify the interface. If I have
any reasonable success with this I'll post it in this newsgroup.

Somebody (Bernie Roehl?) recently posted about a HMD that they made
from a network of LED's and CCD cameras. It was low cost compared to
commercial products and had really good resolution, less than 1 degree
if I recall. But the sensing mechanism did limit head position.

-dave
From: snoswell@ucs.adelaide.edu.au (Michael Snoswell)
Newsgroups: sci.virtual-worlds
Subject: Re: TECH: Maximum lag time?
Date: 18 Aug 92 07:51:16 GMT
Article-I.D.: u.1992Aug20.180805.9510
Organization: Information Technology Division, The University of Adelaide,
Originator: hlab@milton.u.washington.edu



dstamp@watserv1.uwaterloo.ca (Dave Stampe-Psy+Eng) writes:

>In article <l8j4l1INN4ev@news.bbn.com> pjm@bbn.com (Paul J. Metzger) writes:

>>Many helmet display systems we've seen have a fairly large lag time
>>associated with them with an end result being images that appear to
>>slosh around.
>>
>>Our question for the net is: What is the maximum acceptable lag time
>>from when a position/orientation sensor detects new data to when a
>>computer generated image is displayed, such that the "perceived" lag
>>is negligible?

>I don't have my sources handy, but as I recall anything below 50 mS is
>considered negligable, anything over 250 mS is quite nasty.  500 mS or
>more is almost unusable.

Just to really cause a storm - 

I was involved in a study a number of years back to determine if the
rate of visual data processing was linked in any way to intelligence
(by using some very cleverly designed experiments that measured your
judgement of very short visual [and aural in an associated study]
events)..

It turned out that there is a significant correlation.

The brightest people (IQ about 140 or more) had response/processing
times down around 20 milliseconds. This response time increased slowly
to a broad spread of times for IQs in the 80 - 100 range of 50
milliseconds or more. Of course there were data points that went
against the trend, but the comparison was remarkable in general.

Now as most people in VR are pretty bright.... (ducking for cover)..

cheers
        Michael Snoswell

----------------------------------------------------------------------------
  Michael Snoswell                         snoswell@sirius.ucs.adelaide.edu.au  
  Vision Systems Limited                   +61 8 343 0610 <- note the change
  South Australia                          "Profound and witty quote"
Newsgroups: sci.virtual-worlds
From: healy@nosc.mil (Mike Healy)
Newsgroups: sci.virtual-worlds
Subject: Re: INDUSTRY REPORT: Bolt Beranek and Newman (BBN) Inc.
Date: 17 Aug 92 17:12:13 GMT
Organization: Naval Ocean Systems Center, San Diego
Originator: hlab@milton.u.washington.edu



Not to be an apologist for BBN, but SIMNET has always been graphically
oriented.

Mike Healy
ETA Technologies
healy@cod.nosc.mil
From: dewind@acsu.buffalo.edu (Padraig)
Newsgroups: sci.virtual-worlds
Subject: Re: TECH: Volumetric Touch Screens
Date: 19 Aug 92 22:35:22 GMT
Article-I.D.: u.1992Aug20.185356.12309
Organization: UB
Originator: hlab@milton.u.washington.edu



jew5001@zeus.tamu.edu (WILLIAMSON, JOHN EDWARD) writes:

>Now that I am feeling cocky, I would like to build another "VR" type
>of interface.  I vaguely remember reading a description of a home brew
>touch screen interface in _Circuit Cellar_ (???)  by Garcia (??) a few
>years ago.  The author included plans for a grid of photo-cells and
>lights mounted in a frame places over the monitor.  When the light
>path was broken, a signal was sent to the computer so that the
>location could be calculated.  I think the author mentioned
>constructing multiple frames to create a type of "volumetric touch
>screen."

>First, would this work in principle?

Yup...I've seen it used in supermarkets.  It allows someone to touch
the screen where an option is written and thus choose where in the
program they want to go...simple supermarkety types of stuff, but it
can have lots of uses if one was creative enough.

  -Padriag

______________________________________________________________________________
Patrick DeWind                            |  dewind@lictor.acsu.buffalo.edu
SUNY at Buffalo                           |  V077PW3W@UBVMS.CC.BUFFALO.EDU
                                          |  ACSOPTD@UBVMS.BITNET
"She's been everybody else's girl...maybe |
 one day she'll be her own."  Tori Amos   |Be afraid!  Be VERY afraid!!!
------------------------------------------------------------------------------
From: Gregg.Lukomski@mixcom.mixcom.com (Gregg.Lukomski)
Newsgroups: sci.virtual-worlds
Subject: TECH: Straylight Photo VR
Date: 17 Aug 92 18:25:47 GMT
Article-I.D.: mixcom.1992Aug17.182547.29371
Organization: Milwaukee Internet Xchange BBS, Milwaukee, WI U.S.A.
Originator: hlab@milton.u.washington.edu



Is anyone using Straylight's 'Photo VR' system on the PC?

I'm interested in opinions about this product in relation to Sense8's
'World Tool Kit' and any other PC package... Including the VREAM
system...

Also, what is the runtime cost for the full development package w/o
Intel's DVI board...?

       ________________________________________________________________
                             "Cyber-MacGyver"
       ________________________________________________________________
        Gregg Lukomski                       gregg.lukomski@mixcom.com
From: dstamp@watserv1.uwaterloo.ca (Dave Stampe-Psy+Eng)
Subject: Re: SCI: Timestamps...
Originator: hlab@milton.u.washington.edu
Organization: University of Waterloo
Date: Sat, 15 Aug 1992 13:52:53 GMT



cdshaw@cs.ualberta.ca (Chris Shaw) writes:

>NTP uses a sophisticated statistical treatment of message transport to
>get an estimate of the what the real time is, coupled with adjustments
>to the computer's clock to slowly edge the computer time in sync with
>global time. The time variance under NTP is much less than what you'd
>get with the obvious "time a packet turnaround" algorithm.
>
>Which isn't to say this problem is solved, just that synchronization
>is less of a problem than burstiness and transport delay, I think.

I agree that burstiness is going to be the big problem.  I'm not sure
that we need millisecond precision, though: 100 mS is probably more
than enough.  If we assume that initial connection is made to a site
that has the network time set, a "ping" every now and then should be
enough (ordinary maeeages could act as the pings).  Timestamps are
needed mostly for marking the start time of objects or sudden jumps:
everything else is relative times.

--------------------------------------------------------------------------
| My life is Hardware,                    |                              | 
| my destiny is Software,                 |         Dave Stampe          |
| my CPU is Wetware...                    |                              | 
| Anybody got a SDB I can borrow?         | dstamp@watserv1.uwaterloo.ca |
__________________________________________________________________________
From: bobp@hal.com (Bob Pendelton)
Newsgroups: sci.virtual-worlds
Subject: Re: TECH: world description
Date: 18 Aug 92 14:22:44 GMT
Organization: HaL Computer Systems, Inc.
Originator: hlab@milton.u.washington.edu



From article <1992Aug17.060156.22278@u.washington.edu>, by
dlwood@mailbox.syr.edu (David L Wood):

> In article <1992Aug10.091948.19421@icf.hrb.com> jtt@icf.hrb.com (Jack
> Taylor) writes:
> 
> [ a bit Ctrl-K'ed ]
> 
>>On startup data exchange
>>------------------------
>>
>
> Yes, each client will download the universe (well, not the whole thing
> :)) and thenceforth all references to the object will be to the
> object's unique object ID.  The router would say: Want dataset for
> obj#:######, and the client will scan their list of obj id's that it
> already has on disk, and then reply: no, or yes.  The object's
> position/orientation and spatial data will be sent regardless.  Unless
> you have a psychic client. :-)

More likely, you get a message that says, obj:#####@x,y,z,... And when
you find out you don't know what ##### is you ask for its
representation.

Assuming that the other guy knows everything and then letting him ask
for definitions is cheaper than constantly asking if you understand.
It also allows the client to throw away definitions any time it likes
and prevents the router from having to keep track of which client has
which definition.

To bad this approach doesn't work with people... ;->

                                Bob P.
-- 
Bob Pendleton             | As an engineer I hate to hear:
bobp@hal.com              |   1) You've earned an "I told you so."
Speaking only for myself. |   2) Our customers don't do that.
                   <<< Odin, after the well of Mimir. >>>
From: dstamp@watserv1.uwaterloo.ca (Dave Stampe-Psy+Eng)
Newsgroups: sci.virtual-worlds
Subject: Re: DESIGN: Doors between virtual worlds
Date: 11 Aug 92 14:34:25 GMT
Organization: University of Waterloo
Originator: hlab@milton.u.washington.edu



autodesk!robertj@uunet.UU.NET (Young Rob Jellinghaus) writes:

>Ah.  This assumes that the "visual representation" of this portal-door
>can in fact be a projected perspective onto another place.  (It can't
>be a static projection, as then it'd just be a painting.  It needs to
>change in perspective as you move around looking into it.)
>
>I was just thinking of what this kind of door would look like, and it
>occurred to me that there is a physical counterpart: a hologram!  A
>hologram is just a physical piece of plastic which reflects light in
>such a way as to create a three-dimensional view of some objects in a
>virtual space.  These "dimensional doors" would be essentially
>cyberspatial holograms, which allow you to teleport to the space on
>the "other side" by walking through them.  (And what's more, they
>could be _moving_ holograms!)

The easiest way to do this is still to make a visual link to the area
you're viewing through the portal.  Then your machine is doing the
work, not someone else's.  The link functions as if an extension was
made to your region-- visible elements of your region become invisible
behind the portal, and objects from the viewed region are put in place
using the desired portal region transform.  THis handles "weird space"
portals nicely as well.  When the portal dies, the objects are removed
from your viewspace.

Option 2 is to set up an additional renderer, make an image of the
region, and copy it into the image.  Possible, but too expensive for
now.  Imagine, for example, that you are using stereoscopic glasses.
The left and right eye views must have their seperate left-and-right
eye views of the world beyond the portal as well.

Any opinions on the render-and-copy versus the visibility link?

--------------------------------------------------------------------------
| My life is Hardware,                    |                              | 
| my destiny is Software,                 |         Dave Stampe          |
| my CPU is Wetware...                    |                              | 
| Anybody got a SDB I can borrow?         | dstamp@watserv1.uwaterloo.ca |
__________________________________________________________________________
From: dlwood@mailbox.syr.edu (David L Wood)
Newsgroups: sci.virtual-worlds
Subject: Re: DESIGN: Doors between virtual worlds
Date: 18 Aug 92 21:07:50 GMT
Organization: Syracuse University, Syracuse, NY
Originator: hlab@milton.u.washington.edu



There seems to be a lot of confusion about Portals, doorways, icons,
and I must admit I'm caught up in it too. :-)

How many different types of "portals" are there?
I can think of two main types:

portals between two places in the same world &
portals between two places in DIFFERENT worlds.

Also, a few variations on structure:

Portals that allow you to "see" the other side & 
portals with a static representation or 
 no rep at all (a geometric point).

What is the portal really? Where is it run?

It could be user created.  The user could define the location the
portal connects to.  The user could define who is allowed to enter.
The user could define it's shape, and whether or not it is a "window"
type of portal, a la hologram.

- problem: How do you keep a rogue user from hurling portals at other
  users, and possibly zapping people to remote locations of cyberspace?

A portal could, instead or in combination with user ownership, be an
extension of the message router.  The router could handle all the
sticky problems of "window" portals having two different scaling
systems for either side, and pass messages only to those users who can
see through the portal.  The router also, no matter WHICH method is
used, must provide a communication path for those users who pass
through a portal into another world.

For portals that are created by users for entrance into another world,
no matter which router that world is located, there will be a delay as
the next world's data is sent to the user.  In the interim, where is
the user?  If the user passes through a worm hole type of portal, a
nice scene of flying down a tunnel would be reassuring, but how do you
reconcile this with a physical location of the user? Where is the
wormhole?

A portal could also be conceived as an object running some linked
code.  This code would allow for access privileges to be placed on the
portal, and the object itself could take any form or shape needed.
The only problem here, is how to keep yourself from being swallowed by
someone else's portal?

I think this sums up most of the confusion that I see, (err,
experience) about portals.

+-----------------------------+-----------------------------------------+
| dlwood@mailbox.syr.edu      | Gigs and gigs of NiCad memory, bummer.. |
| Cybernaut, with a thought.  | Why buy the leading brand; 90% hate it. |
+-----------------------------+-----------------------------------------+
Newsgroups: sci.virtual-worlds
From: griff@ccwf.cc.utexas.edu (yo'man)
Subject: TECH: 3d audio
Originator: hlab@milton.u.washington.edu
Organization: The University of Texas at Austin, Austin TX
Date: Mon, 17 Aug 1992 22:05:18 GMT



Does anyone know of any sources for 3d audio information?  We're in
the market for a convolvotron like system, and need some technical
information on it - we have DSP boards around here ourselves and are
considering using them.  Any help would be greatly appreciated.

Andrew Wheeler
Applied Research Laboratories
University of Texas at Austin
 
[MODERATOR'S NOTE:  Check the FAQ in the archives.  This information is
in there:

        milton.u.washington.edu    /public/virtual-worlds/...

                                                        - Bob Jacobson]
From: harald@efads1.tuwien.ac.at (Harald Stadlbauer)
Newsgroups: sci.virtual-worlds
Subject: SCI: Feedback in gloves?
Date: 12 Aug 92 13:03:59 GMT
Organization: Technical University Vienna, INFA
Originator: hlab@milton.u.washington.edu



I am interested in research in feeding back any kind of information in
the gloves (some kind of feeling etc.).  Is there any research work
known on this topic?

       Harald Stadlbauer

-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
Harald Stadlbauer, Institute of Flexible Automation, Technical University of 
                   Vienna, Gusshausstr. 27-29, A-1040 Vienna, AUSTRIA
                   e-mail: harald@efads1.tuwien.ac.at
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
Newsgroups: sci.math
From: choy@skorpio.usask.ca
Subject: Organization for search
Organization: University of Saskatchewan, Saskatoon, Canada
Date: Fri, 21 Aug 1992 21:55:38 GMT


The information in libraries is so massive that I cannot read all
of it. However, the information is so incomplete and deep that I
may take me a long time to determine its existence or utility.
Can we place the information in a computer to allow fast search
and a chance to catch up on the pleasures of life? Is anyone doing
this?

Henry Choy
choy@cs.usask.ca
From: jcbhrb@nic.cerf.net (Jacob Hirbawi)
Newsgroups: sci.math
Subject: Walsh Functions
Date: 13 Aug 92 22:28:21 GMT
Organization: CERFnet

Inc sci.math <Bsxv48.Ko7.2@cs.cmu.edu>
Chung Kang Tsen <tsen+@EDRC.CMU.EDU> writes:

 > Can someone give me a brief description of what Walsh Functions are,
 > some of it's applications and also good references to the subject?
 >
 > I am studying applications of Walsh functions in Genetic Algorithms, but
 > I want to know if there are other areas that use (and how they use)
 > it, so I can have a better view of the overall picture.

Walsh functions are nicely described in "Transmission of Information by 
Orthogonal Functions" by Henning F. Harmouth (QA 404.5.H36, 1969).
Especially interesting is the analogy between these functions and 
the more familiar harmonic functions and between "frequency" and "sequency".

Along these lines you may think of the finite Walsh functions and transforms
as being related to the finite abelian group C(2) x ... x C(2) (n times) of 
order 2^n the same way the finite Fourier coefficients and transform are 
related to the group C(2^n) -- in both cases the coefficients are the group 
characters and the transform is character decomposition.

As far as applications, there was someone working here who had an almost
unhealthy fascination with these things -- he was working on non-sinusoidal
radar and went to great lengths to explain what you can do with them. Too bad
he left the company, otherwise I would have asked him to give me the details
one more time! 

Jacob Hirbawi
JcbHrb@CERF.net
Newsgroups: sci.math
From: torkel@sics.se (Torkel Franzen)
Subject: Re: You know, the integers (was: Re: Stupid question about FLT)
Organization: Swedish Institute of Computer Science, Kista
	<1992Aug11.190119.23518@ariel.ec.usf.edu>
	<1992Aug16.172642.13398@sics.se> <1992Aug17.171716.2553@fid.morgan.com>
Date: Mon, 17 Aug 1992 19:04:44 GMT

In article <1992Aug17.171716.2553@fid.morgan.com> sethb@fid.morgan.com 
(Seth Breidbart) writes:

   >Q: What do you mean by "and so on"?

  Your questions apply equally to an explanation of what is meant by "PA",
which was the point of my comments.
Newsgroups: sci.math
From: scavo@cie.uoregon.edu (Tom Scavo)
Newsgroups: sci.math
Subject: functional equation
Summary: Does  f^2 = f'  have a real solution?
Date: 18 Aug 92 17:57:57 GMT
Article-I.D.: nntp.1992Aug18.175757.10216
Organization: University of Oregon Campus Information Exchange

Someone recently brought up the functional equation

     f^2 = f'

where  f^2  is taken to be the second iterate of  f .
I found a solution in the literature (Babbage, 1816)
of the form  f(z) = a z^b , but I'm still wondering 
if a real solution exists.

I'll summarize any significant response, of course. 

Thanks.
-- 
Tom Scavo
scavo@cie.uoregon.edu
From: dmagagno@mcs.drexel.edu (David Magagnosc)
Newsgroups: sci.math
Subject: Re: Still another problem.
Date: 14 Aug 92 14:21:49 GMT
Organization: Drexel University

In article <1992Aug12.075304.28486@newssrv.edvz.univie.ac.at> pm@katz.cc.univie.ac.at (Peter Marksteiner) writes:
>Bill Taylor writes:
>
>
>>Prove that
>>
>>               n     n     n    n
>>     1  /     2     3     4    5        \  
>>     - |  1 + -- +  --  + -- + -- +....  | 
>>     e  \     1!    2!    3!   4!       /   
>>
>>  is an integer for all positive integer n.
>
>Define a differential operator D = (d/dx x), i.e. multiply by x and
>differentiate.  Apply this operator n times to exp(x). It is easy to see 
>that the result is exp(x) times a polynomial in x with integer coefficients. 
>By expanding exp(x) in powers of x we see that it is also equal to
>
>            n       n        n       n
>           2       3   2    4   3   5   4      
>       1 + -- x +  -- x   + -- x  + -- x  +.... 
>           1!      2!       3!      4!      
>
>Now take x=1, and the result follows. 
>
>             Peter Marksteiner
>             Vienna University Computer Center
>             pm@katz.cc.univie.ac.at

This is a very nice proof, but I will say that I am a little surprised
that no one has posted the (correct) value.  Since it follows very
easily from this approach, permit me to summarize.

Let

	D^(n)(exp(x)) = p_n(x) exp(x)

define the polynomials p_n(x).  Then p_n(x) is the sum of terms

	S(n,i+1) x^i

where S(n,i) are the Stirling numbers of the second kind, equal
to the number of partitions of an n element set into i (nonempty)
subsets.  Setting  x = 1,  we see that the desired value is the
number of ways of partitioning an  n+1  element set into any number
of subsets.  The sequence begins  1, 2, 5, 15, 52, ...

To verify the form of the p_n(x), we may construct a recurrence
relation using the operator D and compare it to the known relation
for S(n,i).  Alternatively, we may explicitly determine the
coefficient of  x^m / m!  in the product  q_n(x) exp(x), where
q_n(x) is the polynomial with the Stirling coefficients (and we
want to see that p_n = q_n).  This coefficient is the sum of terms

	(m+1)! S(n+1,i+1) / (m-i)! (m+1)

each of which is the number of functions from an  n+1  element set
to an  m+1  element set with the size of the range equal to  i+1,
divided by  m+1.  Summing, this is then total number of functions
from an  n+1  element set to an  m+1  element set, divided by  m+1,
or
	(m+1)^(n+1) / (m+1) = (m+1)^n

Since this agrees with the coefficients in the original,  q_n = p_n,
and the result follows.


While we're at it, prove that the following sum is always an
integer:

	 n    n    n    n
	1    2    3    4
	-- + -- + -- + -- + ...
	 1    2    3    4
	2    2    2    2

and find reasonable generalizations.

D. Magagnosc
-- 
496620796F752063616E207265616420746869732C20796F752063616E206265636F6D65206120
636F6D70757465722070726F6772616D6D657220616E6420676574206120676F6F64206A6F622E
Newsgroups: sci.math,sci.physics