Jeffery S. Allen
The Global Positioning System (GPS) is a new tool recently added to the growing hardware and software utilities which comprise computer mapping. This chapter will include an explanation of GPS, how it is currently being used, some examples of use in Central America, and suggestions for training and implementation for natural resource management in developing tropical countries.
Accuracy of positional information for navigation and positioning has been something that mappers have persistently pursued over the ages. Some historical maps are almost comical in their presentation and oversimplification of spatial details. However, many historical maps are amazing works of cartography and impressive in their relative accuracy. Previous chapters have compared and contrasted traditional cartography and the use of GIS. One of the issues discussed related to adding information into a digital cartographic database. The most common avenue of entering this data has been the digitizer tablet or table. While entering data in this fashion has improved the efficiency of mapmaking enormously, the utilization of GPS takes digitizing to a new level.
The GPS technology which has emerged recently in the digital mapping community uses satellites for navigation and location finding. It is revolutionizing spatial data capture and could potentially be the most important remote sensing tool since the aerial photograph. This technology has been developed by the Department of Defense (DOD) to support military navigation and timing needs at a cost of approximately $8–10 billion (Leick 1995). The GPS is a constellation of twenty-four satellites (named Navigation Satellite Timing and Ranging, or NAVSTAR) orbiting the earth which became fully operational on December 8, 1993. Each satellite continuously transmits precise time and position (latitude, longitude, and altitude) information. It was initially implemented to give the