Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!ucsd!sdcsvax!ucsdhub!hp-sdd!ncr-sd!ncrcae!hubcap!pixar!loren
From: pixar!loren@ucbvax.Berkeley.EDU (Loren Carpenter)
Newsgroups: comp.parallel
Subject: Re: Seeing 4 dimensions experiment?
Message-ID: <5075@hubcap.clemson.edu>
Date: 11 Apr 89 21:13:24 GMT
Sender: fpst@hubcap.clemson.edu
Lines: 41
Approved: parallel@hubcap.clemson.edu

In article <5050@hubcap.clemson.edu> cam@edai.edinburgh.ac.uk (Chris Malcolm) writes:
>I have heard a rumour that someone implemented a 4-dimensional
>modelling system, which permitted the construction of 4D solids, and
>viewing them (2D projections) on a video screen, on sufficienlty fast
>machinery that users could use joysticks or whatever to navigate around
>(shift the point of view as though moving) in a 4D world. The story
>goes that about half of the people subjected to this exploratory
>experience would exclaim, after less than an hour, "I see it! I can see
>4 dimensions!"
>-- 
>Chris Malcolm    cam@uk.ac.ed.edai   031 667 1011 x2550
>Department of Artificial Intelligence, Edinburgh University
>5 Forrest Hill, Edinburgh, EH1 2QL, UK		


Back in 1969-70 when I was working for Boeing in Seattle, we had 2
CDC 6600's (2-8 Mflop, 60-bit words).  I had been wanting to visualize
4D shapes for some time.  A friend in the systems group told me about
a "graphics" program he had written that would plot dots on the
operator's console (2 512x512 resolution stroke character displays) using
the "period" (.) character.  Well, there were 2 consoles on each 
machine; the one used for tape staging was free on weekends.  So,
the program I eventually wrote generated several 4D shapes: hypercube,
hypersphere, 4-simplex (analog of tetrahedron), and the 3 flavors of
4D torus analogs.  Shapes were modelled with about 2000 uniformly
distributed dots.  Controls included 4D windowing (slice of +- W), 
rotation in a plane defined by any pair of axes, 3D-2D perspective,
translation along any axis, and a few others.  All controls had a
duration or velocity parameter (this was a keyboard, remember).
Depending on the number of visible dots, the frame rate varied from
about 12 to over 50 frames/second.

Anyway, after playing with this for a couple of weekends, I reached
the point where I could predict exactly what I would see before
I typed any command.  I'm not sure if this counts as 4D visualization,
but it was certainly 4D "understanding".  Someday I intend to do this
again with a system that displays surfaces in real time.


				Loren Carpenter
				...ucbvax!pixar!loren