Towards the global GIS

This paper outlines the concept of a 'global GIS,' and defines various aspects of its development, as well as various options and decisions that must be made. The emphasis is on the advantages and disadvantages of maintaining a global topological structure, and whether topology should be generated 'on the fly' in response to a specific query. We first define what we mean by 'space' in this context, followed by a description of topological structures and how we may use them in the context of graph traversal problems. We then describe some appropriate data structures. After mentioning some of the real-world problems associated with polygon construction problems, we touch on how graphs may represent change over time. A global topological structure is then proposed which resolves some of the problems mentioned. This is based on incremental graph updating methods. Some unresolved problems associated with using global topological structures are then discussed, especially those associated with queries, such as polygon overlay, that generate a new local topological structure. We conclude with some preliminary rules, and suggest further work.Department of Land Surveying and Geo-Informatic