Geographic Information Systems (GIS) [89] are increasingly being cited as a motivating application for computational geometry research. According to Unit 1 of the NGCGIA Core Curriculum [63], ``a GIS can be seen as a system of hardware, software and procedures designed to support the capture, management, manipulation, analysis, modeling and display of spatially-referenced data for solving complex planning and management problems.''
The key phrase is ``spatially-referenced data.'' A database system that combines data sets of different types from different sources about different features/objects is likely to find that converting data sets into a common form dominates the processing efforts, when it is possible at all. Data that can be assigned a spatial location, however, can be combined by simply displaying data sets simultaneously on a map or computer screen. Add a mechanism to select which data sets to display, and you have a rudimentary GIS.
Many systems have been developed in natural resource management applications-either in connection with remote sensing or from computer-aided design tools-and some have been highly successful in making up-to-date information available for management decisions in a manner that was not possible using a large inventory of paper maps. GIS use in government and marketing applications continues to expand.
Of course, a rudimentary GIS leads to the complaint [81]: ``A GIS is basically a tool that mines data and displays it. It doesn't clean it up, or maintain it, and seldom even looks to see if it's reasonable.'' Computational geometers see their potential contribution here: in providing the algorithms and data structures to support analysis of geometric data. A forthcoming special issue of Algorithmica, editted by J. Snoeyink, will focus on the interface between computational geometry and GIS.