Electronic Maps Get Data Specific Via Geographic Information Systems, Computers Can Track Patterns and Trends for Planners

Article excerpt

EVERY work day, police officer Michael Byers takes eight colored pencils and draws on a map of Durham, N.C.

He is tracking major crimes. If the procedure seems a little archaic ("something right out of caveman," Officer Byers laughs), the idea makes sense. Each crime has its color. By pinpointing when and where the crimes occurred, officer Byers hopes to spot patterns and trends.

Add the power of a computer (as Durham soon will) and the process becomes a geographic information system or GIS.

Mike Watson, chief appraiser of the Bell County (Texas) Tax Appraisal District, knows what GIS can do. For years, his office used big paper maps to track property ownership and value. When the county installed a GIS system a few years ago, he and his colleagues were surprised to discover land they never knew existed before. Some plots had been overlooked and gone untaxed for years. Meanwhile, the appraisers found that other plots fully described and collecting delinquent taxes didn't exist at all.

GIS is a simple idea.

"You have used GIS all your life," says Richard Pabst, manager of GIS solutions for IBM's Mid-Atlantic area. For example, some-one wanting a tennis racket might look up sporting goods in the Yellow Pages, find a store's address, then use a map to find how to get there.

That's GIS, Mr. Pabst says. "You took some information and an objective and tied them to together."

A computer usually does this by digitizing a paper map or aerial photo (turning it into a series of dots, lines, and spaces that the computer can display). Each dot, line, or space is linked to pieces of information stored in the computer. So, a dot might represent the number of people living at that coordinate, their age, or their income. A line on a road map might be tied to data identifying it as a paved road, a superhighway, or Interstate I-70.

A paper map might show some of these details. GIS allows people to play with all the variables and ask sophisticated questions. For example: Show all the places in California where most of the residents are at least 50 years old, earn between $35,000 and $50,000, and have bought a car in the last 18 months.

GIS computer systems have been around for more than 20 years. In the early '70s, utilities began using the technology to track maintenance and react to problems on its power lines. Those early systems required expensive mainframe computers and software. As hardware and software costs have come down, more businesses are looking at GIS for all sorts of uses.

In a large room of an IBM facility here in Raleigh, N.C., company officials show how one of their IBM PS/2 desktop machines might handle a retail store marketing decision.

The screen displays the location of a store and all its competitors in the area. The retailers wonder whether they should move to a new location. …