
	The Willamette Galley A Bi-Monthly Newsletter Volume 4, Issue 3, July 2001

GIS for Technical Writers

By Judy Jewell

It's easy to define GIS with a quick throwaway line, "oh, you know, it's fancy computer mapping." But just as technical writing is more than the easily blown off, "oh, computer manuals and stuff," a GIS, or geographical information system, is more than just a fancy map.

Old-fashioned paper maps are based on visual measurements. For instance, when you draw a map of how to get from the freeway to your house (does anybody still draw these maps?), you're relying on your visual memory of that route. Cartographers have traditionally used more sophisticated ways of measuring distances and elevations, but traditional maps are basically generated in the same precisely artistic way as they were when Lewis and Clark mapped their route 200 years ago.

What makes GIS So Cool?

A GIS-produced map has databases at its core. Layer upon layer of data determines the look of the map. One layer may contain information about roads, with another focusing on rivers, and a third showing contour lines or buildings. Each data point corresponds to a precise physical location. Moreover, access to the underlying databases is just a click away from the onscreen map. (For instance, you can pull up a tax lot map and click to see how much your next-door neighbors paid for their house.)

Whenever there's data, there exists a primal human urge to manipulate it, and smart data manipulation is what makes desktop GIS such a powerful tool for businesses, environmental scientists, public health analysts, and urban planners. By querying the database (sort of like doing a Boolean search), a GIS user is able to refine the look of a map, and look for spatially based relationships.

A Public Health Study

In one ongoing Massachusetts study, addresses of 2,600 Cape Cod women with breast cancer were geocoded (linked to specific map coordinates) and combined with various land-use databases. One layer of data focused on areas of past and present heavy pesticide use, including areas that are now residential but where pesticides were used in the past. Another database identified areas where groundwater used for drinking may have been contaminated by septic tanks.

In this study, GIS factored in multiple variables such as specific qualities of the possible pollution source, distance and direction of the source from the subject's residence, and whether there were intervening factors, such as a forested area, that may have reduced a subject's exposure to a source. At this point in the study, it does not appear that the Cape-wide excess of breast cancer can be explained by the local military reservation, radar station, or nuclear power plant. Other environmental factors are still being studied, with particular emphasis on small areas with a markedly increased incidence of breast cancer.

What's In It For You

Maybe, as a technical writer, you'd like to enhance your documents with a few classy maps. GIS-produced maps can make tremendous graphics for any technical document that has to do with place or spatial relationships. And while most government agencies and environmental engineering firms have in-house GIS experts, a very basic knowledge of GIS will get you an inordinate amount of respect from these folks.

One software company, ESRI, dominates the GIS world. Their desktop GIS program, ArcView, is just arcane enough that it helps to take a class to learn its ins and outs. Portland Community College's geography department offers an introductory class twice a year (the summer class is a week-long intensive), but online classes from ESRI are much handier and quite reasonably priced.

For more information, including good GIS links, visit www.esri.com. For details on the Cape Cod breast cancer study, see www.silentspring.org.

Judy Jewell is currently updating Lonely Planet Pacific Northwest. Lonely Planet recently switched their mapping from AutoCad to ArcView, and Judy found that by just saying the word "geocode" she became the chief cartographer's new best friend. She can be reached at jajewell@home.com.