Geographic Information Systems (GIS): Mapping the Territory
What is GIS?
A recent Los Angeles Times article spotlights the need for GIS technicians (see Gottlieb in the bibliography). An undergraduate class at Hunter College in New York City presents their class GIS projects. A public librarian in Washington State and one in Missouri speak enthusiastically about GIS in their local communities, and the tools it offers to patrons. But what is GIS, and what can public libraries do with it?
GIS stands for Geographic Information Systems. While the map is not the territory, as Borges wrote, GIS permits a much more complete mapping of a particular place or event by layering both spatial and tabular data in the same image.
A Geographic Information System comprises data, software, hardware, and human methodology to allow problem solving to proceed in an almost entirely new way, by the visual inclusion of spatial data in the analysis of problems. GIS enables an overlay of information to trace maps, use patterns, demographics, transit lines, soil levels, or other data in a way that combines information and displays it graphically to facilitate decision making. Maps can be layered with business and demographic information to produce sophisticated patterns of land use, consumer growth or decline, traffic patterns, and so on.
George Soete in his Transforming Libraries document on GIS (written for the Association of Research Libraries) provides a lucid example of what can be done with GIS: by layering in GIS format information on city bus lines, below-poverty-line incomes, and public health clinics, one can graphically illustrate and analyze the need for more clinics or the importance of adding bus routes.
Other examples of how GIS data can be used range from the correlation of clusters of illness with possible environmental hazards to the mapping of potential café locations with pedestrian traffic.
Much of the data used in GIS is not new, but in new formats: maps that are digitized, census data that is machine-readable, tables that are computer-produced. What’s so exciting about GIS is that these kinds of information can be layered to produce a multidimensional construct that was very difficult, if not impossible, to create before. GIS allows a great flexibility in the application of spatial and numerical data and enables each to illumine the other.
The Environmental Systems Research Institute, Inc. (ESRI) produces a large family of GIS products (ArcView) and maintains a Web site that describes GIS, how it functions, and what it does. ESRI describes GIS in this way: “A GIS stores information about the world as a collection of thematic layers that can be linked together by geography.”
How does GIS work?
GIS can run on a variety of hardware, from desktops to servers. Software includes a database management system, a graphical user interface, and tools to manipulate, analyze, and visualize geographic information. The most important part of a GIS is the data. Spatial and tabular data are the matrix from which GIS illustrates the answers to queries and can model possible answers. Geographic data can be stored as “vector” or “raster” models (for a technical description of these terms, see ESRI’s site). Baldly simplified, “vector” describes points, lines, and features as a collection of x,y coordinates; “raster” images model continuously varying features like soil types or costs. GIS systems handle both vector and raster models.
GIS data comes from many sources, most notably the federal government with its push to provide census and many other kinds of information in machine-readable form. GIS output is visual, and some of the sites linked to in this Tech Note provide images of GIS output.
Public Libraries and GIS
Academic libraries have been offering GIS for at least the past decade. Public libraries are beginning to, in some cases sparked by grants, like one given by ESRI to San Bernardino County Library in California, a project just beginning. Other public libraries have offered GIS for some time, as we will see in Missouri and in Washington State.
GIS is not cheap, and its use requires a fairly intensive learning curve. The librarians we spoke to, however, were most enthusiastic in their promotion of GIS services, which they felt offered a key information source to their users, one that will prove as indispensable as internet access.
Anna Sylvan is the manager of GIS for the St Charles City-County Library District in O’Fallon, Missouri. St. Charles has been offering such services since 1994, when Sylvan came to the job. Her primary customers have been local businesses seeking to expand, and new businesses seeking to target specific consumers for their product or services. Others search for more personal reasons: an Asian-American family looked for school districts with large Asian-American populations in the county so their children would not be isolated.
Sylvan stressed that GIS is not intuitive: one needs training to manipulate the data. She takes appointments to train people in its use, and says that they respond favorably. Like many librarians, Sylvan rose to the challenge of a new technology in which she had no previous background or knowledge.
At Seattle Public Library, GIS librarian Joan Johnson says the use of GIS ranges from teens doing term papers to nonprofits working on grants to elder couples researching their own property. Her focus is on service and collection development, making sure the data sets are current, and that lots of manuals provide backup. Johnson not only trains users in GIS, but goes herself to regular training in the technology. In Seattle, every department in the city uses GIS, and the city supports training for all staff who are using it.
She says that her time (GIS takes up about 50 percent of her professional time) is spent not only in training patrons to use GIS, but also in promoting the GIS services the library provides. Her library is a government documents repository, and she notes that 80 percent of government information has a spatial component. With its focus on city of Seattle data, Johnson sees a key role for the library in providing GIS data for Seattle’s neighborhood community councils. Data includes housing values, demographics, census information, and so on.
She draws a parallel between GIS and internet training, which grew naturally out of the need to provide an increasingly necessary information service to users initially unfamiliar with the technology. Johnson trains users one-on-one, in sessions up to an hour at a time, in using ArcView, ESRI’s widely used software.
GIS is costly in terms of both funding and resources. The rewards for information access are great, however. It provides a tool that simply did not exist before, and public libraries now have the means to place it in their patrons’ hands.
Bibliography
Soete, George J. Geographic Information Systems. February 1997. SPEC Kit 219. Association of Research Libraries. 40p. Entire text, with links, is on the Web. An excellent introduction to GIS.
Environmental Systems Research Institute, Inc., maker of widely used GIS software. Very clear explanations and very nicely designed.
“Current Literature on Geographic Information Systems and Libraries” is a bibliography by Cathy Moulder, curator, Lloyd Reeds Map Collection, McMaster University Library, Hamilton, Ontario. Last updated in April 2000, it includes links where possible and covers the past decade thoroughly. While obviously weighted toward academic collections, there’s a lot of useful background for anyone interested in GIS.
A Guide to GIS Resources on the Internet. Last updated in Feb 1998. Lots of links to sites, tutorials, projects, and bibliographies.
Census Tiger 1995 Data. TIGER is Topologically Integrated Geographic Encoding and Referencing, a digital database of geographic features, such as roads, railroads, rivers, lakes, political boundaries, census statistical boundaries, etc. covering the entire United States. Last updated Feb 1999.
New York State’s GIS Related Sites. Huge list of links to GIS sites across the country. Last updated Jan 2000.
Mike’s GIS on the net home page. Mike’s a geographer in Ottawa, and his page is a rich source of GIS links with an emphasis on Canadian sources.
GISMO Geographic Information Systems and Mapping Operations. GISMO is New York Metropolitan Area’s largest GIS users group, with over 400 members from city, state and federal agencies, non-profit organizations and the private sector. Their Web site contains a list of members, information about local activities, and a link to their discussion list archives.
There are many geography and GIS-related online discussion groups. A general one is GIS-L.
A Yahoo! search on 4/26/00 yielded software sites for 83 GIS, ten for geospatial metadata.
Two articles discussing GIS applications: Gottlieb, Jeff. “Computers put new job field on the map: a marriage of technology and cartography has college campuses scrambling to accommodate the opportunities in geographic information systems” in the Los Angeles Times Education section, B2, February 23, 2000. The title says it all.
Pine, John C. and James H. Diaz. “Environmental health screening with GIS: Creating a community environmental health profile” in Journal of Environmental Health, April 2000. p9–15. A long but fascinating article on using GIS to find if there is an association between concentrations of poverty and health outcomes.
Prepared by GraceAnne A. DeCandido for the Public Library Association, May 2000. ladyhawk@well.com
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