Navigation

Author: Dan Searles

Navigation issues appear in two distantly related areas of virtual reality. One is finding your way around in a computer generated virtual world, and the other is finding your way around large data sets or in large information systems. In either case, it is easy for a user to get lost and disoriented, and not know how to proceed. Different systems have different solutions to the navigation problem.

In a virtual world where the user is immersed, it is easy to become lost or confused. Although some virtual worlds are limited, most require you to move around in them to experience more of the world. Virtual worlds may include doors or windows through which the user can pass, exposing new parts of the virtual world. Large worlds can include sign posts or other familiar mechanisms to guide the user around. There may be unique locations which are easy to return to through the use of a gesture or command. Confusion comes from the computer generated nature of the world. Unless the world designer creates extra detail, many positions and views within the virtual world look similar.

Computer generated worlds also have to deal with the boundary problem. The boundary problem exists because virtual worlds are much smaller than the real world, and different designers use different methods to handle it. One may just prevent further movement, while another resets the user's position to the opposite side of the world. A third possibility is to let the user move off into emptiness, letting them find out for themselves that they are lost.

The second major area where navigation is a concern is when attempting to locate specific information in a large information system. A large information system can be as small as a book, or as large as all the information in the world. Planning a search for information over such a vast set of resources can be a daunting task. Real books have a table of contents, indexes, and other navigation aids. Libraries have card catalogs. Electronic versions of books have similar features, but commonly make use of "hyperlinks". Hyperlinks allow the user to jump to another part of the book where related information is located. Electronic media exists in far more forms than books and libraries. There are electronic versions of sound recordings and video data and there are thousands of computer databases and networks of computer resources.

Overviews and Landmarks are two techniques which can help with the navigation problem. Overviews are like a book's table of contents. Subject areas are condensed into short descriptions and hyperlinks can be used to get to the more detailed information. Overviews can be hierarchical and span vast quantities of data. More sophisticated overviews can use graphics techniques to highlight and represent data in a symbolic manner. Landmarks provide familiar reference points to help guide a user. A typical example is to provide a hyperlink to a book's table of contents, index or other significant contents at the bottom of each page. This enables the user to quickly jump to a known location at any time. In a virtual world landmarks provide the same function as landmarks in the real world ie. they trigger memories of actions that have been done before at that location.

Several navigation tools have been developed. On the Internet, tools such as Gopher and Archie can be used to locate specific information. Hundreds of smaller tools have also been developed, such as CYBERMAP [Gloor 91], SaTellite [Tsichritzis 90] and TableView [Carey 90] to address the navigation problem at various levels. But much work remains to be done finding methods to organize and access a world full of information.

Related topics: Library Science.

References

[Tsichritzis 90] Tsichritzis, D. (1990). SaTellite: Hypermedia Navigation by Affinity. Proceedings of the ECHT'90 European Conference on Hypertext. pp 274-287.

[Carey 90] Carey, T., and Hunt, W. (1990). Roles for Tables of Contents as Hypertext Overviews. Proceedings of IFIP INTERACT'90: Human-Computer Interaction. pp 581-586.

[Baudel 93] Baudel, T. and Beaudouin-Lafon, M. (1993 July) CHARADE: Remote Control of Objects using Free-Hand Gestures. Communications of the ACM. 36(7): 28-35.

[Murakami 91] Murakami, K. and Taguchi, H. Gesture recognition using recurrent neural networks. Proceedings of Human Factors in Computing Systems (CHI'91), ACM Press, 1991, pp. 237-242.

[Bolt 84] Bolt, R. The Human Interface. Van Nostrand Reinhold, New York, 1984.