wex@dali.pws.bull.com (Buckaroo Banzai) (08/18/90)
In article <BRUCEC.90Aug10152147@phoebus.phoebus.labs.tek.com> brucec%phoebus.phoebus.labs.tek.com@RELAY.CS.NET (Bruce Cohen;;50-662;LP=A;) writes:
Problem being: if you didn't know you would want this information before
the project started, do you have the tools to to extract it?
Indeed. That is one of the reasons I sought a completely-general theory.
At MCC we saw any number of tools fail for reasons including a too-limited
ability to display the information they contained. In general, it takes a
lot of work to put information into the system and people want to be well-
rewarded for the time and effort they've put in.
Conversely, you can have systems which are extremely flexible and general
and fail because no one puts in enough useful information. That's more a
sociological problem (though important to solve).
Agreed, but that still doesn't address navigation, which is the nastiest of
all the problems in my opinion. The whole reason for spatial metaphors is
to allow users to apply their highly-evolved spatial perception and
visualization systems to the navigation problem. These systems, though,
are evolved to handle relatively circumscribed local areas, which may be
somewhat, though not arbitrarily, cluttered (like the space in the branches
of a temperate zone forest?). They break down in high-dimensional, large
hyper-volume spaces. We don't as yet know what aids can help this, or how
to optimally filter the perceptions of such spaces for easy navigation.
True. The key is to *not* navigate in semantic space. That's too slow,
cumbersome, and prone to error. There are reasons for doing it at times;
they have to do with the merger between navigation and editing (another
complex topic in itself).
This, by the way, is the common error made by hypertext systems. They have
the user navigate in the same space as the hypergraph is laid out, often
restricting one to node-to-node travel. Highly inefficient and bewildering.
The current best choice seems to be to "project" (in some sense not
necessarily related to projective geometry) the navigation space onto
some less complex space the user can handle, and provide disambiguation for
the inevitable overloaded volumes. I think you need to consider this up
front when investigating the spatial qualities of a cyberspace. No matter
how interesting a space may be from the viewpoint of abstract organization,
if users can't find their way through the maze, it's not a useful space.
True, but if you can step out of the maze entirely and get an "overview"
then navigation becomes much easier. Benedikt hinted at this same idea in
his presentation at the cyberspace conference - his slides were highly
artistic and conveyed as much of the "feel" as you can get from a static
shot. I hope they will be reproduced in the book (but since they were
color, they may be too expensive).
The other key to navigation is to leave behind the methodology of linear
movement. This is *very* hard, since that's how we move every minute of
every day. But if we can learn to do things like teleport, use landmarks
and so on, navigation becomes possible (if not yet easy).
If the desired qualities of a space are
determined by the objects within it, then it follows that different
collections of objects should reside in different kinds of space. Maybe
what we are calling cyberspace is just an anteroom filled with doors and
rabbitholes into these spaces ...
You're on the verge of discovering waypoints. Doors and rabbitholes are
indeed the way to go. However, please remember that what I am describing is
a theory that may be embodied in many different ways in different
implementations.
[I said:]
There are lots of issues here, such as: what about ordering? what kinds
of dimensions should there be? what about properties that are not
confined to a single object, but are the result of object-interaction
(such as the property earlier-version-of, an important concept in
software engineering).
[and got the reply"]
Yes, please, I'd like to hear your thinking on all these issues.
You don't ask for much, do you? OK, here's a quickie: I think that ordering
is of two kinds: theoretical and practical. The theory of numbers tells us
that the number one comes before the number two and so on. However, only a
test of the processes in a queue can tell us that process one is before
process two. You have to somehow let people know which kind of ordering
they're seeing.
I think there are several kinds of dimensions, more or less along the same
lines as Will Bricken laid out in the posting that started all this.
I think relational properties need to be represented, and are best done with
extra-object annotations (such as arrows or lines between objects).
I think there's lots more to say, but I haven't a lot of time. Sorry 'bout
that.
--
--Alan Wexelblat phone: (508)294-7485
Bull Worldwide Information Systems internet: wex@pws.bull.com
"Politics is Comedy plus Pretense."brucec%phoebus.phoebus.labs.tek.com@RELAY.CS.NET (Bruce Cohen) (08/19/90)
In article <WEX.90Aug17182647@dali.pws.bull.com> wex@dali.pws.bull.com (Buckaroo Banzai) writes: > > True. The key is to *not* navigate in semantic space. That's too slow, > cumbersome, and prone to error. There are reasons for doing it at times; > they have to do with the merger between navigation and editing (another > complex topic in itself). > > This, by the way, is the common error made by hypertext systems. They have > the user navigate in the same space as the hypergraph is laid out, often > restricting one to node-to-node travel. Highly inefficient and bewildering. I suspect that the realization of this error is what is driving all the work in overlaying existing graphs with trails and scripted tours. In the large-scale kinds of cyberspace people keep talking about, I think the only solution is intelligent "guide" programs, which can build up a navigation space with a suitable topology to match what a user needs at any given time. > > True, but if you can step out of the maze entirely and get an "overview" > then navigation becomes much easier. Well, yes, but this isn't the panacea a lot of people think it is (you can tell I've had this discussion before). We tend to think of an overview like a map, which shows all the important spatial relationships down to some minimum scale. This doesn't work well for high dimensional continuous spaces or highly connected non-continuous spaces. Overviews in high dimensions tend to be more like document outlines than maps. > The other key to navigation is to leave behind the methodology of linear > movement. This is *very* hard, since that's how we move every minute of > every day. But if we can learn to do things like teleport, use landmarks > and so on, navigation becomes possible (if not yet easy). The user still needs to have some sort of mental model of where she's going to go when she teleports, or steps through a trapdoor to the next level down. People can accept nonlinear movement, but they still need a map of some sort that they can internalize at some level of detail. The key point of all this discussion, which I doubt very much we disagree on, is that it's very important to consider the cognitive and sensory capability of the person inhabiting the virtual world when designing it. Developing a taxonomy of design or implementation spaces for these worlds is a useful project, but we can't let that be the end of our thinking about the use and variety of space in Virtual reality. The real-world 8-) virtual reality designer is going to have to deal with (at least) two kinds of space, the world design space and the user navigation space, and the mapping(s) between them. > > You don't ask for much, do you? OK, here's a quickie: I think that ordering > is of two kinds: theoretical and practical. The theory of numbers tells us > that the number one comes before the number two and so on. However, only a > test of the processes in a queue can tell us that process one is before > process two. You have to somehow let people know which kind of ordering > they're seeing. Good point. And that ordering is likely not static. The upshot of that is that the landscape you're trying to navigate through is probably changing on several different time scales; some of those changes are local to your current locality and on a time scale at least as fast as or faster than your own movements. The map keeps changing, inpart due to your own actions, but only in part. > > I think relational properties need to be represented, and are best done with > extra-object annotations (such as arrows or lines between objects). > I agree. We can learn an awful lot from the way such annotations are handled in thematic maps which try to merge several different kinds of information. I woudl like to see more people in the hypertext/vr area studying the way physical and thematic maps are designed; there's a lot of useful prior art there. -- --------------------------------------------------------------------------- NOTE: USE THIS ADDRESS TO REPLY, REPLY-TO IN HEADER MAY BE BROKEN! Bruce Cohen, Computer Research Lab email: brucec@tekcrl.labs.tek.com Tektronix Laboratories, Tektronix, Inc. phone: (503)627-5241 M/S 50-662, P.O. Box 500, Beaverton, OR 97077