From: edlantz@aol.com (Edlantz)
Subject: Re: HUMAN-FACTORS: Immersion Studies
Date: 4 Oct 1996 19:55:01 -0400
Organization: America Online, Inc. (1-800-827-6364)


Dr John P. Wann < J.P.Wann@rdg.ac.uk> writes in response to my comments:
<...>
>> Is an HMD the best solution?  Probably not.  A wide FOV
>> projection display such as the Reality Centre will suffice.

>...SIDs are grossly INEFFICIENT in their use of physical space and
>computational resources and can only be justified if their usage is
>very high (e.g. entertainment) or if the novelty value outweighs the
>cost...

John, you left out one other case which is often the driver:
collaborative work environments.  Decisions are usually made in
groups.  A group of engineers in a realtime CAD design review wearing
HMD's are terribly isolated from one another and all have different
points of view.  New participants have to be trained in the proper use
of such a system.  Also, a multi-user system requires multi-HMD's and
multi rendering pipes which quickly exceed the cost of projection
video.

>If a large corporation wants to provide elegant demo's of their
>products, irrespective of cost, then a dedicated large screen-multiple
>projector system may be a worthwhile investment.  If architects and
>clinicians are going to use VR as a routine visualisation aid they are
>not going to have access to such systems.

Keep in mind that commercial SID systems are young and have not yet
been optimized for low cost.  "SimCenters" are emerging which lease
time on these systems making them (potentially) profitable.

>By locking the displays to the users perceptual systems (e.g. HMDs)
>you make a very efficient use of both space and computational
>resources.  Which is why you can generate quite a nice HMD immersive
>display based around a PC for $3,000 and you need in excess of
>$100,000 and a large dedicated space to contemplate a SID.

You are mixing apples (low end HMDs) with oranges (high-end SIDs).
For starters, a $3,000 HMD is probably giving you less than VGA
resolution.  A three-projector SID provides 3M+ pixels.  What if we
modified an inexpensive home projection TV to project onto a wide
curved screen.  As long as the user's head remains stationary, the
resolution would be comparable to the HMD.  Now, if we let the user
relax in their "armchair" and rotate their view with a hand controller
rather than getting up and looking around, we have an inexpensive SID.
Stereoscopic could be added by numerous means.  I call this "Armchair
VR."  Brian Park has a system similar to this (floman@eden.com,
www.flogiston.com).  Is there a demand for systems like this?  I don't
know.

>If you are trying to sell the SID-VR to business then sure you need a
>pretty convincing case (and I haven't heard one yet) that justifies
>how VR will bring "added value" that offsets the capital cost in a
>very short time.  Its much easier to justify investing =A310,000 in
>dual seat HMD syste= m so that companies can monitor their usage and
>put a "toe-in the water" of taking the technology on-board.

They are buying them now.  There are corporations that can save
millions by discovering a single design flaw in an oil rig or chemical
plant before it is built.  SIDs make commercial sense here.
High-resolution displays, unencumbered group viewing, a fully
collaborative environment, low user fatigue, viewer training not
required... frankly, many of these corporations view HMD's as toys or
lab curiosities as far as their applications are concerned.

>As the VR industry moves away from HMDs it will severely limit the
>market-place in which it can operate.

I do not see the industry as a whole moving away from HMDs.  Rather I
see a cost-effective new way to deliver VE content to a larger number
of people.  Both technologies have their pros and cons.  For instance,
imagine a system which allows one or a few users to directly interact
with each other using HMDs while spectators view the live action on a
SID with a commentator's view point.  Could be the sports of the
future!

Ed Lantz
edlantz@aol.com