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What is GIS?

GIS is a computer program for storing, retrieving, analyzing, and displaying data. It combines two kinds of information or databases. GIS stands for Geographic Information System.

One is geographically referenced information: latitude & longitude coordinates, spatial or location information, "where things are".

The second is attribute or descriptive information: characteristics or qualities of that place, "what things are like". Attribute data could be census information (e.g., population, housing), natural resources (e.g., trees, soil types), infrastructure (e.g., buildings, roads) or events (e.g., # of accidents).

When the geographic and attribute information are layered or put together, GIS creates a map to show you what the place is like: where accidents occur in your community, where teenagers live in your state, etc.

What layers of information you combine depends on your purpose — you need different information to find the best location for a new soccer field than you do to analyze the environmental damage from a tornado. You may use existing data (e.g., census), or create your own (e.g., walk around your neighborhood and use GPS to record the location of every oak tree). The information is computerized (scan, keyboard entry) and stored until you request that it be mapped in the way you define.

 

What is GPS?

GPS is a navigational system that can accurately locate your position anytime, anywhere, and regardless of weather on Earth. Developed by the United States Department of Defense, it uses 24 satellites orbiting the earth at altitudes of approximately 11,000 miles to transmit data.

The handheld GPS receiver processes data from several satellites to "triangulate" the receiver's exact location, using latitude and longitude. Uncorrected positions determined from GPS satellite signals produce accuracies in the range of 50 to 100 meters. When using a technique called "differential correction", users can get positions accurate to within 5 meters or less.

GPS has a number of important applications such as search and rescue missions, helping pilots avoid collisions, and accurate application of farm fertilizers and other chemicals. Recreational uses include a navigational tool for orienteering, hiking, hot air ballooning, boating and many other activities. GPS provides any point on earth with a unique address (its precise location).

An important 4-H use of the GPS receiver is to identify or mark the precise location of things or events in their community that are important for your project or program, and then enter location information (e.g., of pine tree, car accident that resulted in 3 deaths, where nitrogen in the stream exceeds a certain level, etc.).

GPS tells us where while GIS tells us what. Together, they help us locate, organize, and map our communities.