In a way, GIS systems are like a sophisticated web browser opening a well-designed page. The user can click on certain options and just one level of information is presented, or several levels may be blended to present a new image.

In a single data base, or a series of linked data bases, a GIS can hold data on aerial images, road maps, landmarks, crop cover, county lines, and so on.

GIS has its roots in computer-aided design software for the aerospace industry. All that does is map points in space and assign them values, right?

Except that while an airplane wing follows a set of mathematical curves, nature is viciously random. A meandering stream would require thousands of points to map it with accuracy and precision.

That made the job of building maps in computers exceptionally expensive. It has become affordable only in the last few years as computer prices fell and power rose, and as programs were developed to take advantage of the years of work with expensive machines that only government agencies could afford in the 1970s and '80s.

GIS has become affordable enough that farmers are moving into the new field of precision agriculture where computers help direct how much fertilizer and water to apply, when to harvest, and other activities.

For archaeologists, GIS can speed the analysis of a site, collating a season's worth of notes, aerial and satellite images, location drawings, surveys, and other data so they can figure out what it all means.

Author: Dave Dooling
Curator: Bryan Walls
NASA Official: John M. Horack