M@IN - Accessing Spatial Data Tutorial
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What is a GIS?
A computer system for capturing, managing, integrating, manipulating, analyzing, and displaying data which is spatially referenced to the Earth -- International GIS Dictionary
An information technology which stores, analyzes, and displays both spatial and non-spatial data -- H. Dennison Parker, formerly Publisher, GIS World
Automated tools for the efficient storage, analysis, and presentation of geographic data -- Jack Dangermond, President, Environmental Systems Research Institute
A decision support system involving the integration of spatially referenced data in a problem solving environment -- Dr. David Cowen, University of South Carolina
Several common themes are inherent to each of these definitions.
GIS can also be thought of as a distinct technology made up of the following components: computer hardware; GIS software; users and systems personnel; procedures, standards, and policies; and data.
What Are GIS Applications?
GIS technology supports the use of geographic data in a variety of ways, often called applications.
Map Making - Custom maps, showing selected data layers, can be displayed on the computer or generated as a hard copy product. The user can define the scale and the area to be mapped. Data layers can be added or deleted to fit the user's requirements.
As noted earlier, GIS technology emphasizes analysis rather than map making. Analytical applications in GIS cover a broad range of topics but typically involve the integration of different data layers to solve a problem or answer a question.
Site Selection - Where is the best location for a county landfill, a new restaurant, or a highway by-pass? The GIS user first defines the site selection criteria. For siting a landfill, the criteria may include the geology, soil type, current land use, location of protected lands (parks or wildlife refuges) or environmentally sensitive areas (water supply watersheds), proximity to roads, the cost to purchase the land parcels, etc. The GIS permits the integration and evaluation of the geographic data to identify areas that meet the pre-defined criteria.
Emergency Response Planning - A hurricane is approaching the North Carolina coast. Using GIS, emergency management personnel can evaluate a variety of data layers, including elevation, storm characteristics (strength, speed, direction), land use information, population distribution, and transportation networks to identify the areas that may be inundated by the storm surge, the population that may be affected, and the best evacuation routes.
Network Analysis - How does a school system determine school bus routes and schedules? In North Carolina, administrators use GIS, analyzing factors such as traveling distance, speed limits, student addresses, school locations, and class schedules to select routes that minimize the number of buses and gas costs.
Environmental Applications - What is the potential impact of a proposed new housing or industrial development on a community's drinking water supply? Which forest areas need to be preserved to prevent damage to economically important, recreational trout fishing streams? Is a proposed new drinking water supply located too close to an abandoned waste site? In each of these examples, GIS can be used to integrate and evaluate multiple data layers and attributes and then generate information that enables public officials and resource managers to make more informed decisions.
How Can I Use GIS?
The applications described above represent only a few of the almost unlimited number of applications that GIS technology can support. GIS can also be used to display and analyze existing statistical data. How can you use this powerful tool to:
Identify the areas of western North Carolina where the poverty level exceeds the state average?
Find the trout fishing streams for Macon county?
Define the distribution of students' residences throughout a school district?
Locate the state parks on the coast of North Carolina?
The two indispensable requirements are:
Software and Data
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