Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!uakari.primate.wisc.edu!dali.cs.montana.edu!milton!brucec%phoebus.phoebus.labs.tek.com@RELAY.CS.NET From: brucec%phoebus.phoebus.labs.tek.com@RELAY.CS.NET (Bruce Cohen) Newsgroups: sci.virtual-worlds Subject: Re: Semantic space, "round 2" Message-ID: Date: 18 Aug 90 19:04:12 GMT References: <9007250107.AA01311@hitl.vrnet.washington.edu> Sender: hlab@milton.u.washington.edu Organization: Tektronix Inc. Lines: 82 Approved: hitl@hardy.u.washington.edu In-Reply-To: wex@dali.pws.bull.com's message of 17 Aug 90 22:26:47 GMT In article 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