Geographic Information Systems
Geographic Information Systems (GIS) are designed to store, manipulate and display data relating to locations on Earth's surface. Common applications are land inventories, the census, urban planning, environmental and resource management, marketing, and so on, where the data banks contain locational references such as a county, the boundaries of land parcels, the limits of tree species, the position of road intersections, etc. Equivalent terms for such information are "spatial" and "geo-coded" data. GIS employs computer technology because computers are quick and efficient in processing and manipulating large quantities of data. GIS systems need these capabilities to handle the vast quantities of information they contain. Smaller systems are frequently used in marketing, locational analysis, education, etc.
Canada has been a pioneer in the development of GIS. The Canada Geographic Information System (CGIS), initiated in 1963 by the Agriculture Rehabilitation and Development Agency, was the first operational land resource GIS. GIS is now operating under Environment Canada. Another early system was the Geographically Referenced Data Retrieval System of Statistics Canada, started around 1965. Several Canadian universities were pioneers in the creation of GIS techniques and prototype systems. Many of the concepts and methods developed for these systems are now routinely incorporated into new systems. Also, the development of commercial products has been very strong in Canada.
Large GIS are predominantly operated by federal and provincial agencies, but there is a growing number of mid-size applications of GIS in urban planning, forest and petroleum industries, utilities, conservation, and Native affairs. It is predicted that the usage of GIS will continue to expand.
Key issues in GIS are geometric dimension, topological relationship, data structures and databases, spatial analysis and cartographic display. Geometry provides the basic indexing structure for the data. Usually, latitude and longitude or their derivatives are being employed. Topology concerns itself with the relationship between geographic features.
GIS contain some of the largest databases available and it is therefore important to identify efficient data structures. On the other hand, these structures ought to replicate human perceptions of spatial structures as much as possible to make analysis and presentation more elegant. The most effective analysis is often visual analysis and the computer's flexibility is a very powerful help here. GIS users also have a range of statistical and other quantitative tools at their disposal.
See also Computer-Assisted Mapping.