HUMAN-COMPUTER INTERACTION SECOND EDITION
Dix, Finlay, Abowd and Beale

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Chapter 13 Groupware 13.3.4 Virtual collaborative environments Page 475

Given the virtual environment is within a computer, it makes sense to allow participants to bring other computer-based artefacts into the virtual environment. However, many of these are not themselves 3D objects, but simple text or diagrams. It is possible to map these onto flat virtual surfaces within the 3D virtual world (or even have virtual computer screens!). However, text is especially difficult to read when rendered in perspective and so some environments take advantage of the fact that this is a virtual world to present such surfaces face on to all participants. However, now we have a world the appearance of which is participant dependent.

Chapter 13 Groupware 13.3.4 Virtual collaborative environments Page 475

The video wall allows people from remote locations to meet. In a sense it extends the normal physical space of the participants as they can see the remote room, but the image rendered is a real physical space, albeit on a video screen.

Chapter 13 Groupware 13.3.4 Virtual collaborative environments Page 475

The Nottingham Internet Foyer merges these two worlds. In a real physical foyer at Nottingham University there is a large video screen. However, what you see when you look at it is not a room in a remote building (as with a video wall), but a fixed view of a virtual space. The virtual space that is seen is itself a collaborative virtual environment, a sort of virtual foyer, which participants can enter over the Internet using either desktop or immersive VR systems. The embodiments of the electronic participants are visible to those at the real foyer. However, in addition, the video image of the real foyer is also projected onto a surface in the virtual foyer. Thus the physical foyer and the virtual foyer are linked by a virtual video wall! the real foyer the electronic foyer -->

Chapter 13 Groupware 13.4.2 Meeting rooms Page 477

There are about half a dozen such rooms at present catering for groups of between four and 30 participants. These include Xerox PARC's CoLab [227], Project Nick [24] and Capture Lab [151]. The general layout consists of a large screen, regarded as an electronic whiteboard, at one end of the room, with chairs and tables arranged so that all the participants can see the screen. This leads to a U- or C-shaped arrangement around the screen, and in the biggest room even several tiers of seating. In addition, all the participants have their own terminals, which may be recessed into the tabletop to reduce their visual effect. Figure 13.6 shows a computer-supported meeting using NLS, a very early groupware system [82]. Obviously changes in display technology have made the displays less obtrusive, but the basic principle remains.

Chapter 13 Groupware 13.4.2 Meeting rooms Page 478

Such systems will support various forms of working including private use of the terminals and subgroup working on a teleconferencing or email basis. However, the characteristic mode of operation is where all the participants' screens and the central screen show the same image. This is termed WYSIWIS ('what you see is what I see'). The screen then takes the form of an electronic whiteboard, similar to a simple graphics drawing package, on which the participants can all write. One advantage of such an arrangement over a normal whiteboard is the ease with which data can be moved to and from the participants' normal computer files. As more work is prepared on-line this will increase in importance. Also the electronic whiteboard has some advantages over the real thing. Whereas on a real whiteboard you can only write and rub out, on the electronic version you can move items around just as you would with a drawing tool, and, of course, you can get a printout of the results rather than just hoping the cleaners do not wipe it all off.

Chapter 13 Groupware 13.4.2 Meeting rooms Page 479

The simplest policy to implement is to use locking, similar to that described previously. When a participant, say Jane, wants to write to the screen she presses a key, or clicks on an on-screen button to request the floor. If no one else has the floor, she may go ahead and type on the screen, or if it supports graphics draw a diagram. When she has finished, she relinquishes the floor, using some other key or mouse selection. However, if some other participant, say Sam, already has the floor when Jane requests it, she must wait until Sam relinquishes the floor. There will be some sort of status indicator to say who has the floor at any moment, so Jane can ask Sam to relinquish, just as you might ask for the pen to write on a whiteboard.

Chapter 13 Groupware 13.4.2 Meeting rooms Page 479

A conceptually simpler idea is to let everyone write to the screen at the same time -- just as people may use several pens to write on a whiteboard at the same time. This sounds like a recipe for chaos, with people forever writing on top of one another. However, with reasonably small groups there is little problem. Try going to the whiteboard as someone is writing on it, and writing on top of what they write. It is possible, but it does not make you many friends. Similarly in the electronic version, as soon as two people begin to write on the same part of the screen they say 'oops!' and start to write elsewhere.

Chapter 13 Groupware 13.4.2 Meeting rooms Page 479

The various forms of locking constitute a software protocol for floor control. The way that people negotiate for screen space in the free-for-all situation is a social protocol. The reason that this is possible is because the participants are in the same room and are able to talk to one another.

Chapter 13 Groupware 13.4.2 Meeting rooms Page 479

If there is only one floor holder, then the screens can all show the floor holder's cursor. However, as soon as several participants are active at once, it is less clear what to do. One option is to display all the users' cursors. These may be accompanied by the user's name so that you can tell who is entering what. With large numbers of participants this can become distracting, and it is costly in terms of network traffic. The alternative is to show none of the cursors. If the participants are talking as they write, it is usually obvious who is writing what. In addition, during brainstorming phases, anonymity is an advantage -- people are more likely to put up an 'off-the-wall' suggestion, thus stimulating more ideas and discussion.

Chapter 13 Groupware 13.4.2 Meeting rooms Page 479

If you are using a real whiteboard, you may go up to a diagram on the board and say 'I think that should go there'. As you say the words 'that' and 'there', you point at the relevant parts of the diagram. This is called deictic reference or simply deixis. If the participants' cursors are invisible to one another, then this form of pointing is impossible. Indeed, in such a meeting, even where the cursors are visible, the participants may momentarily forget and point at their own screen. Obviously the participant can get up and point at the shared screen as you would at a whiteboard, but that is rather intrusive and precludes writing at the same time. To allow this deictic reference a group pointer may be supplied. This is an icon visible on all the screens, perhaps in the form of a pointing finger. Any participant can pick it up with his own mouse and use it to gesture on the screen. The control of the group pointer poses similar problems to those of floor control. However, the most lenient locking policies work well since the use of the pointer is usually synchronized with speaking, and thus it is easy to avoid and resolve conflicts.

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