to significant changes in classical man-machine interfaces. It is opening new opportuni-
ties for the implementation of computer technologies.
Devices are traditionally placed in input and output groups.The new tendency is to
combine these into devices allowing both input and output.Touchscreens and HMD's
would be examples.With reference to the various human senses that the human-com-
puter interaction devices exploit, the following different technologies can be defined.
Visual interface technologies
The current focus on the visual communication channel in HCI has not prevented a
significant amount of development in other technologies currently on the market.There
are several broad aims, including increasing screen sizes and resolution, making displays
three-dimensional, and implementing new technological approaches.
One of these approaches aims at very large and very thin displays that will lead to
improvements in portability and enable development of paper-like, pen-based computer
interaction systems very different in feel to today's desktop workstations.This trend dates
back to 1963, when Ivan Sutherland created Sketchpad, an interactive drawing tool which
enabled users to draw points, line segments and arcs on a cathode ray tube with a light-
pen.The device that popularised and brought this type of interface to the public eye was
the Apple Newton MessagePad. More recently, the 3Com PalmPilot, with an even smaller
display than that of the Newton, has become a very popular pen-based platform. Its appli-
cations have very few on-screen controls and the pull down menu at the top of the
screen is normally hidden.The PalmPilot does not recognise normal Latin letters but uses
its own Graffiti character set , entered in a dedicated area of the screen. Its core applica-
tions are the same as the Newton's. Pen-based interfaces have been used in a number of
other computer applications, including word processors, spreadsheets, music editors and
air-traffic control systems.
Another track of work is on devices which give more realistic images and encompass
spatial positioning.They are often described as `three-dimensional' (3D), although not all
devices support 3D visualisation.This report concentrates on two innovative types of
computer visual devices:
- Devices which actually produce an image by themselves (Head-Mounted Displays
and helmets).These contribute to building immersive VE's;
- Glasses which transform the way the user sees the image on a standard monitor
(Liquid Crystal-Shutterglasses).They contribute to the development of semi-immer-
One type of semi-immersive or immersive VE display suitable for the culture environ-
ment is the Computer Automatic Virtual Environment, or CAVE for short. Developed by
the University of Illinois in Chicago, the CAVE consists of up to six large display screens
arranged in a cube. Stereo graphics are projected onto each screen, and multiple users
can stand in the middle of the cube and engage with the VE. If additional head-tracking
technology is provided for one of the users, the perspective will change in sympathy with
the movement of his or her head.
In addition, there are the Chameleon-type displays for VE use.These employ a handheld
display whose position and orientation details are tracked in order to determine what
appears on it. Additionally, the display may enable interaction with what it is showing.
This technology is not as revolutionary in the display type or specifications as in the
combination of tracking, visual output and interaction.