Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!eos!eugene
From: eugene@eos.UUCP (Eugene Miya)
Newsgroups: comp.graphics
Subject: Re: 4D Visualization (If you think you do it, you probably don't)
Message-ID: <6174@eos.UUCP>
Date: 10 Feb 90 00:25:42 GMT
References: <99@emtek.UUCP> <16033@well.sf.ca.us> <6162@eos.UUCP> <487@enuxha.eas.asu.edu>
Reply-To: eugene@eos.UUCP (Eugene Miya)
Organization: NASA Ames Research Center, Calif.
Lines: 71

In article <487@enuxha.eas.asu.edu> hollasch@enuxha.eas.asu.edu (Steve R. Hollasch) writes:
>In article <6162@eos.UUCP>, eugene@eos.UUCP (Eugene Miya) writes:
>What's the point?  With the 3D object you can gain insight into
>clearance, structure and so on.  More importantly (for me at least),
>you can spot trends, maximum regions, minimum regions, and the like.
>Heck, if you go backpacking, you don't disregard your topo map because
>it's not the true 3D object, do you?

I didn't say that.  You can spot some trends, but your comment about
manipulation is the key.  You see a maximum, but display in science
requires frames of reference, what is the max value, not just that it exists.
You want value(max), or value(max), or |value(max)-value(min)|.
And I certainly don't disregard topos especially those I drew.

The problem with trends is the following: you can't simply predict
something on the basis of solely using imagery.  Given a ball at starting
point A and ending point B, plot intermediate locations.  You must
assume something.  Some naive artists will linearly interpolate,
fine rolling on a flat surface.  But suppose A is higher than B.
Gravity changes non-linearly in position.  You probably know the
beautiful strobe photos (visualization) of Harold Edgerton,
who recently died.  I thought about writing an obituary for him.
Muybridge who did the first photographic motion studies drew incredible flak
from artists who thought they knew the way to portrary animals and people
in motion.  (He has a biography published by the UCa which shows how
drawing changed.)
Bottom line, you have to have additional information to predict or
understanding trends.

>    So, you project an image of the globe to the screen, and you now
>have before you a virtual 3D globe.  Provide for user manipulation of
>this globe, and very soon (s)he'll be able to estimate relative sizes,
>distances, and the like.  This is a good example of "bumping-up" a
>dimension to gain insight into the actual data.

My only comment is that the estimation is very bad.  I would want the
image software equivalent of a scale or ruler.  Again more quantative
info which visualization systems don't have but CAD systems do.

>    I'm sure you've seen the dataglove & visual helmet combination
>pioneered by NASA as a means to model "real space".  Why can't this as
>effective as walking around to a globe and rotating it?  Or would our
>2D retinas hold us up?  =)

Yes, Scott and Mike's lab is just over in another building.
This brings and important issue: using the real world to work with
images.  On a screen I can hold a ruler/scale up.  No good its a
rendering of a 3-D object (right?).  Can't do it easily with stereo systems.
You have your virtual globe in the middle of the room, what mechanism
can one place a the tape measure in my pocket to measure distance?

>    Eyes can be deceived quite easily, but they one of the best ways
>that humans have to rapidly and intuitively grasp many of the
>properties of objects, and to quickly isolate interesting regions.  I
>will choose visual information over tactile or aural information (are
>you thinking of another method of perception?) almost every time.

Sure.  No one will disagree, but that's why we have microscopes, telescope,
lenses, Gieger counters, and whole slews of scientific instruments.
Bottom line: visualization just does not go far enough.

Anyways basically good points.

Another gross generalization from

--eugene miya, NASA Ames Research Center, eugene@aurora.arc.nasa.gov
  resident cynic at the Rock of Ages Home for Retired Hackers:
  "You trust the `reply' command with all those different mailers out there?"
  "If my mail does not reach you, please accept my apology."
  {ncar,decwrl,hplabs,uunet}!ames!eugene
  Do you expect anything BUT generalizations on the net?