Geographic information systems: How a World Wide Web presence can improve their availability

Geographic information systems (GIS) are increasingly being used for effective accessibility to spatial data. A GIS comprises much more than the mere storage of data: spatial data of the earth is being manipulated to create new information, perform complex spatial analyses, and generate maps and reports. An automated GIS system consists of an integrated digital database containing information about geographic features (points, lines and areas); the hardware, software and people used in the analysis of the features (geographic coordinate data); and a description of features (attribute data). It also provides the ability to query manipulate and analyse the data. However, certain problems exist in the way access is gained to geographic data. Currently geographic data sets (e.g. maps) are scattered across South Africa and the world, with no standardised method of accessing them. Data needed by a specific GIS system must be 'ordered' or downloaded from a remote site. No centralised index to existing geographic data exists. The results from a specific GIS analysis are not necessarily directly available to others. When downloading and thus duplicating a set of complex data from an external site, with the purpose of further manipulation, the copy gradually becomes less current when compared to the original data set. In this paper it is argued that most of these problems can be addressed effectively by making GIS data and information available via the Internet's World Wide Web. By creating hypertext links between different GIS sites, data sets could be shared between sites: a type of online atlas system with a task-oriented user interface geared towards map creation and fact extraction could be developed. A number of experimental interfaces between GIS application software and the Web have already been developed: these and other approaches are discussed.