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What is GIS?
by David Smith, UNL Extension Assistant
A Geographic Information System (GIS) is a computer system that is used to construct, record, analyze, manipulate, and display geographic information. Geographic information is simply any data that is geographically referenced or that has known earth coordinates(i.e. Latitude/Longitude, UTM, State Plane). Some definitions of GIS also include the personnel and the specific data used as part of the total GIS.
Features: The power of a GIS is the geographic information, the coordinates of the earth's surface, that allow data to be integrated and combined. Features such as points(e.g. wells, street signs), lines(e.g. roads, rivers) and polygons(e.g. houses, crop fields) can be created in a GIS and coordinated with other databases into one large GIS, and then queries and decisions can be made on the entire GIS or specific elements depending on the desired application.
Attributes: Features are fairly useless unless information or attributes are attached to them. This is the next step and another powerful piece of GIS, making information about specific elements available and easily accessible. Each feature in a GIS has attributes that help define it, and are important to a user of a GIS. For instance, polygon features such as houses could have associated attributes of address, ownership, legal description, and size. This process ties all the information about a certain element of the landscape into a concise format that is easily queried, and just as importantly, easily analyzed and manipulated.
Databases: Databases form the backbone of a GIS. They are the information that is brought together by the software and the people working on a specific project. The data in a GIS consist of layers of information that can then be combined to give an entire picture to a geographic topic or project.
Washington D.C. and Surrounding Area
For example, a city planner wants to examine the best route for a new expressway. The planner, using a GIS, assembles the data layers that would allow them to examine all the possible influences of the project and make the best decision about the expressway. Possible databases they would want to incorporate could be land use, water, zoning, land ownership, pipelines, population, wetlands, topography, and probably many more. The planner can then use this information to analyze possible routes, potential conflicts with existing features, costs, and potential level of use. The outcome then would be a well informed decision based on a number of scenarios and all possible pertinent information.
The potential benefits accrued from using GIS are extensive with a few discussed here. Of course, GIS is reliant on computers, which allows for the automation of all the geographic data, and the use of the software required for much of the conversion, construction, and analysis of data. GIS takes the place of much of the paper, hard-copy, products associated with geographic data, such as maps. Once the data is digitized, the maps and other hard-copy data sources are then in digital form and can be accessed and used from the computer. This allows for many different sources of information to be combined and integrated. Where different maps and data were in various formats or coordinate systems, GIS allows all of this information to be easily used in combination. New geographic features can be constructed and incorporated because of the base geographic data already in the computer.
Just as important as the ease and availability of geographic data is what can be done with the data. The vast majority of a GIS is its construction; assembling and developing the data, attributing, and integrating. Once the construction is complete, the databases can be analyzed and queried for specific purposes. The use of GIS is basically up to the imagination and desire of the individual. An idea that is geographic in nature is most likely feasible with the use of GIS.
Examples of Using GIS
GIS is rapidly increasing in its use and importance in many fields and disciplines. As stated, any geographic phenomenon can be potentially used in a GIS. For instance, GIS has been used extensively in wildlife research to examine topics such as home ranges, habitat use, and nesting sites. Power and utility companies have employed GIS to map and examine power networks, analyze use of their product, and determine the best locations for future structures. Municipalities have used GIS in emergency response situations to determine the best routes for navigating to a certain location. These few examples of the use of GIS are just a small portion of the many applications where GIS is being applied. The use of GIS is expanding all the time, and GIS has been a benefit for a vast number of industries, both public and private.
PHOTO Credit: Vicki Jedlicka
Lincoln's biosolids recycling program is a joint collaboration between the City of Lincoln, Public Works and Utilities Department and University of Nebraska-Lincoln Extension in Lancaster County with assistance from the University of Nebraska Agronomy Department, Lincoln/Lancaster County Health Department and the Natural Resources Conservation Service.
University of Nebraska-Lincoln
in Lancaster County
Barb Ogg or David Smith
Web site: lancaster.unl.edu
444 Cherrycreek Road, Suite A, Lincoln, NE 68528 | 402-441-7180
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