From: almond@statsci.com (Russell G. Almond)
Subject: Animation and 3-D (Re: Anyone using stereo 3-D?)
Organization: Statistical Sciences, Inc., Seattle, WA USA
Date: Wed, 16 Sep 1992 02:01:29 GMT

In article <1992Sep15.030259.5923@zip.eecs.umich.edu> schuette@quip.eecs.umich.edu (R. Wade Schuette) writes:

   Wade Schuette Writes:

   Just curious about who in the world is doing what with low-end
   stereoscopic 3-D on amiga's or PC's or Mac's or Suns or whatever's
   low-end for you.  (like, using Sega glasses, not StereoGraphics
   CrystalEyes or a pair of microscopic Televisions attached to ... ) .

You don't need stereo pairs if the animation is good enough, the
motion is sufficient to give you the illusion of depth.  This has been
known in the Statistics world for some time, and a lot of the work on
rotating point clouds is to allow us to look at 3-D data on 2-D
screens.  (In answer to the original post, there is currently a lot of
Statistics software out there which does this.  Xgobi, I believe is in
the public domain.  MacSpin is a classic example, and StatSci's S-PLUS
has those features.)

There is an interesting story about rotation and stereo pairs.  An
early version of PRIM-H supported both rotation and stereo, on a
relatively high end system.  We did a classic experiment where we took
a 3-D normal point cloud (equal variances, no covariance) and removed
a "ball" consisting of about 20% of the points from the center of the
distribution.  Any 2-D projection would look approximately normal, and
neither rotation nor stereo alone was sufficient to show the problem,
however, both rotation and stereo pairs would.

We later ported the program to an Apollo workstation without the
stereo stuff.  We decided to build a movie based on our work called
"Visual Aspects of 3-D Data Graphics:  A Movie" (Almond, Huber,
Ramos, Roseman and Thoma: Peter Huber produced it; I directed and
photographed).  For this purpose we produced a special animation
version of PRIM-H which would allow us to:  (1) input commands we
normally imputted through mouse and key interaction using a simple
script language (I needed to write a macro preprocessor for the script
language), (2) Would "click" a camera shutter through a serial line
which was hooked up to a "blue box" animation/time-lapse controller
which drove the camera through a sound sync motor.  An interesting
feature of this settup was that we could use essentially time lapse
photography.  I used 8 second exposures to get good color saturation
(with a high T-stop) and the computer would click the shutter after
the image was drawn.  Thus, even though it took half a night to shoot
100' of film, we could show it back at 24 frames per second.

While the narration explained the "experiment" with the normal
distribution, the movie displayed it; telling people how they really
couldn't see the effect.  At the higher speed of 24 frames per second
and with correspondingly smaller increments for the rotation (we were
getting about 6/frames per second off of the 1983 hardware) the
audience could all see it quite clearly!

BTW, the trickiest portion of the whole enterprise was lining up the
animation with the verbal clues in the narration.  In order to do
this, I first ran some test talk throughs of the narration, to get
timing marks for the animation.  I then twiddled the animation script
so that it would match the queues.  Finally, I had to have the
narrator match the verbal queues with the video test print when we
recorded the sound track.  A real trick.  After the first movie we
learned to avoid phrases like "We color the affected points yellow,
NOW"  for phrases like "We color the affected points yellow;" that
gave us more margin for error.

Does anybody have any experience trying similar tricks in some kind of
hypermedia environment?  I've been thinking that a perfect on-line
tutorial would have the computer running through some script
demonstrating the functionality while a recorded narration described
what the program was doing.  Can this be done?  Has anybody tried it?


			Russell Almond			   
Statistical Sciences, Inc.		U. Washington
1700 Westlake Ave., N Suite 500		Statistics, GN-22
Seattle, WA  98109			Seattle, WA  98195
(206) 283-8802				
almond@statsci.com			almond@stat.washington.edu




Newsgroups: comp.graphics.animation