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GPS

GLOBAL POSITIONING SYSTEM (GPS) technology is an accurate method for GIS data input. GPS uses a network of 24 satellites above the earth transmitting signals, and receiving equipment on the ground, to determine geographic location. GPS was developed in the U.S. for the military, and now is used widely for navigation at sea, surveying, vehicle routing, and other uses. Many car manufacturers and rental companies offer GPS technology as an option or as standard equipment in new cars.

As a data input device for GIS map making, a GPS unit can be used to find x,y coordinates for geographic features by simply going to where the feature is and collecting the positional information that is transmitted from the satellites. (Walking over to an Oak Tree in your school yard and sitting down with your portable computer and GPS device).

Many GPS receiving units are extremely portable, and many also record the coordinate information onto disks which can be translated right into a GIS.

Point features can be located and recorded quickly, and line features can also be input with GPS. A map of roads can be created by driving along and collecting the positional information as you go. Another important GPS feature is the ability to record other types of information, (using a keypad on the receiver) such as what the name of the road is that is being recorded. This also translates directly from the GPS receiver to a GIS, making it an "almost" automatic way to create accurate GIS layers.