When I first came to Israel, in the early ’70’s, my wife and I settled on a kibbutz in the Northern Galillee. I worked in the field crops branch, operating tractors and various tilling equipment. The manager of field crops, being well organized and fresh out of agronomist training, wanted to improve the record keeping: what jobs were completed, when, and where. Instead of tables of columnar data with dates, jobs, and names of each field, I came up with a scheme of overlaying clear plastic sheets on a survey map of the fields, and drawing on the sheets with colored markers when each tilling job was completed. This exercise pre-dated modern GIS software by about 15 years
Little did I realize that decades later I’d be sitting at a glowing monitor, doing similar exercises. The colored markers gave way to a mouse, and the cellophane sheets became computer files. But the driving motivation is the same.
GIS, like optical illusions, can reveal information that is “right in front of your eyes” but not immediately visible. By overlaying different spatial data layers, we discover new relations. Using GIS techniques to superimpose disparate information, we scratch away the camouflage, and expose new surfaces.