Chapter 15

Out of the glass box

15.1 In Section 15.9, we look at alternative interfaces for users with special needs. How could standard interface design be improved to provide better access to these users?


This depends on the particular needs of the user, but in general the more an interface relies on a single channel (such as the visual channel) for information the more likely it is to be unusable by some people.

Multi-modality and redundancy in the interface will alleviate this problem by providing alternative views of the information and so not excluding a user group with restricted use of the primary channel.

It is more satisfactory to encourage multi-modality as a design principle than to provide special systems or 'add-ons' to cater for extra-ordinary user groups. This can also benefit the average user since it reinforces the information over several channels.

However, this may not be possible in all cases: clearly, for example, a user who has limited control of hands and voice may need special equipment such as the Eyegaze system which will track eye movements. Where possible such specialized equipment should be integrated with standard applications to enable the disabled user to use readily available machines and software in common with other users. This is particularly important in the work environment.

15.2 Data visualization techniques have often increased our comprehension of phenomena: consider the effect that 3D graphics has had on looking at complex models such as those of the atmosphere or the ocean, or in understanding the structure of molecules. What do you consider to be the areas that may benefit most from virtual reality visualization techniques?


This exercise could be expanded to allow students to carry out a brief literature review on the applications of virtual reality techniques. In general they are most promising in areas that cannot be explored in reality, either because it is physically impossible (such as in the manipulation of molecules discussed in Section 15.10.1) or physically dangerous, as in space. Models can be physically manipulated and interacted with using virtual reality methods rather than simply observed. Chemical and medical research, meteorology, oceanography, seismology are all areas that could benefit from such techniques.

15.3 Virtual reality has found a number of applications in the games market. Is this a suitable use of such technology? Discuss the possible benefits and disadvantages of exploiting leading edge technology in a leisure market.


The leisure market is important to the computer industry and, being commercially lucrative, can provide an impetus for development which can then be exploited in other spheres.

If virtual reality takes off in games it will result in the development of cheaper equipment and more robust techniques, since the games customer tends to be young (and not overly rich) but with sophisticated expectations. Indeed, many research projects in universities are currently using equipment developed specifically for games, since the more powerful, general purpose equipment is prohibitively expensive.

Another possible advantage is that it makes the technology familiar and therefore accessible and acceptable.

A possible disadvantage is that the use of this technology in games may trivialize it so that it is not considered as a serious solution to other more weighty problems. However, this seems less likely than the advantages outlined above.

15.4 What are the major achievements of computer vision? What are the major problems that still remain to be solved?


Computer vision is being used in a number of application areas, where the images are used to provide input to the computer: for example, face recognition in security systems, monitoring airports and public areas for suspicious behaviour, analyzing scans and x-rays, particularly to identify objects in packages, analyzing aerial photographs for cartography and military uses. The success of such systems has been limited and most computer vision is still at the research or experimental stage.

There are a number of problems still to overcome. These include coping with variation in images, such as orientation, shading and light changes; dealing with scenes which include partially occluded objects; speed of scene analysis.

Again this exercise provides students with a focus for a brief literature review on the subject. A textbook on computer vision or artificial intelligence is a good place to start.

Worked exercises

The following appears as a worked exercise in Chapter 15:

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