Geographic Information System/Global Positioning System (GIS/GPS)

Geographic Information Systems

The earliest forms of GIS were developed in response to several apparently disparate requirements. First, measurement of properties such as area or length from paper maps had always been notoriously tedious, slow, [Page 317]and inaccurate when performed by hand, whereas computerization offered speed and precision. Second, manual editing during the mapmaking process could benefit from computerization, just as editing of text had done. Third, researchers studying transportation were drawn to the advantages of computerization to handle the diverse types of geographic information needed in planning. Finally, statistical agencies in many countries were quick to adopt computerization because of its advantages in handling and aggregating large volumes of geographically referenced data. By the late 1970s, the scale economies of addressing all of these applications with a single technology had become clear, and a GIS software industry began to develop.

The Internet had a dramatic effect on GIS, beginning with the release of the first browsers in 1992. At first, applications emphasized top-down dissemination of data, and many governments invested in digital libraries of GIS data. Metadata standards were promulgated and widely adopted, supporting the search and discovery of data meeting user-defined needs. One of the first of these was the Alexandria Digital Library at the University of California, Santa Barbara, developed beginning in 1993 as an online mechanism for accessing the extensive holdings of the university's map library. Today, many such repositories of geographic information exist, and some have reached petabyte (1,000 terabytes) scale. Today the concept has evolved into the geoportal, a single point of entry to the holdings of many participating digital libraries. The U.S. government's Geospatial One-Stop is typical of this genre.

While data download by sophisticated users dominated early applications of the Internet, by 2000 it was clear that server-side applications would reach a much broader user base. In this mode, data remain at the server and are processed by a remote user using the server's software. Such services offer a limited functionality compared to client-side GIS but address common applications. An early example is Mapquest, a service based on a database of streets and roads that allows users to find addresses and display them in map form and to obtain driving directions between two such addresses. These functions are now available in a variety of forms and accessible through a range of mobile devices. In 2005 Google Earth and Google Maps gave many users their first experiences of the power of GIS to manage and display geographic information and to execute simple functions. Moreover, the publication of the application programming interfaces (APIs) of these services allowed users to develop their own advanced applications.

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