From: schraudo%beowulf@ucsd.edu (Nici Schraudolph)
Subject: Re: "Space"
Date: 6 Aug 90 22:38:17 GMT



wex@dali.pws.bull.com (Buckaroo Banzai) writes:

>We can map the properties of objects one-to-one onto dimensions of
>cyberspace.  The dimensions reflect some element of meaning (semantics)
>about the objects; thus, semantic dimensions.  An N-dimensional space of
>these dimensions is a semantic space.  I conceive of cyberspace as a
>semantic space.

Buckaroo's suggestions don't strike me as useful for either visualization,
navigation or manipulation of virtual objects:

To visualize an object in it you have to somehow embed the semantic space in
our plain old 4-D spacetime.  The entire cognitive engineering problem resides
in the design of this embedding, yet you are very vague about it.  Could you
tell us specifically what sort of embedding you had in mind?

Humans have intuitive navigation abilities only for 2-D spaces, and fare very
badly in higher dimensions and alternative geometries.  Ever played "wumpus"?
It's played on a 3-D dodekaeder, and even though that's a comparatively simple
space you usually get lost after a few moves.  Humans can navigate complex
spaces only with the help of cognitive artifacts (maps, paper & pencil, ...),
and using them in VR therefore defeats the whole idea of VR as a user-friendly
interface.

For object manipulation the data structures used should accommodate the most
frequent operations used on the data.  A vast sparse product space (which is
what Buckaroo suggests) strikes me as the LEAST useful organization of data.
Why not use VR implementations of such time-honored computer science data
structures as trees, inverted lists, priority queues, and so on?
--
Nicol N. Schraudolph, C-014                nici%cs@ucsd.edu
University of California, San Diego        nici%cs@ucsd.bitnet
La Jolla, CA 92093-0114                    ...!ucsd!cs!nici