Geography Related Terms and Definitions


SCDHEC Shared and Integrated Geographic Information System
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Terms: A-F  
Address Matching  
The process by which a GIS point layer is generated by calculating a geographic coordinate by comparing an address located in a table to an address in a line layer containing address information. A location is assigned a coordinate based on rules and standards and accuracy of the address information.
Buffer Zones
An area that is created around a feature at a specified distance away from that feature.
Cartography
The art, science, and technology to spatially represent a phenomena through map making.
Choropleth Map
A thematic map that represents a geographic area that is assigned a distinctive color or shade based on an assigned value for that geographical phenomenon. Values are grouped into classes. Maps should use between 4 to 6 classes. Also referred to as an area or shaded map.
Coverage
A coverage is a vector GIS layer for ESRI ArcInfo software that stores the geographic location and attribute information for a geographic feature. The associated tables are stored as a directory with a corresponding ‘info’ directory.
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Terms: G-K  
Geocoding
See Address Matching.
Geographic Information Systems (GIS)
GIS is comprised of software, hardware, people, and procedures to generate, view, and manipulate information that is geographic in nature.
Global Positioning System (GPS)
Intranet
A network that links computers internally in an organization and is separate from the outside world.
Internet
A network that links computers world-wide.
IP Address
(Internet Protocol Address) A numeric address assigned to a machine enabling it to be located on the Internet.
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Terms: L-R  
Layer
A geograpihc feature that has been grouped into one idividual data level either by topic or geographic characteristics and represented as either a point, a line or an area which is registered to a common geographic coordinate system. (Also refered to as the Thematic Layers or GIS Layer
Map Algebra
The application of simple operators on thematic layer(s) or attribute(s) that results in a new layer based on the formula applied. Some operations include: arithmetic ( +, -, /, * ), boolean (and, not, or, and/or,true, false), relational (<, <=, <>, =, >, and >=) , logarithm, power, and trigonometric.
MrSid
A file format developed by Lizardtech that uses a high compression ratio to reduce "tiff" file size to improve load and view time when using images (for more information refer to LizardTech). Exit SCDHEC
Proportional Symbol Map
A thematic map that uses points to represent a phenomena found in a geographic area that is sized based on a value.
Raster
The representation of a geographic feature by a series of uniform cells organized into rows and columns and assigning a real-world value to each cell to depict an attribute (typically square). Size of the cell varies depending on scale (example: 100m x 100m).
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Terms: S-Z  
Shapefile
A shapefile is a vector GIS layer for ESRI ArcView software that stores geographic location and attribute information about a feature. It is comprised of three required files: .shp (file that stores the geometry), .shx (file that stores the index of the feature geometry) , and .dbf (file that stores the attribute information). A shapefile can also include the following files with a layer but are not required: .sbn, .fbn, .ain, .prj, and .xml. All associated files should remain together.
Vector
The representation of a geographic feature by using points, lines, or areas (polygons).
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References:
Bernhardsen, Tor. 1992. Geographic Information Systems. Biak IT: Arendal, Norway. ISBN 82-991928-3-8.

Dent, Borden D. 1993. Cartography Thematic Map Design, 3rd. Edition. Wm. C. Brown Publishers:Dubuque, Iowa. ISBN 0-697-13589-6.

ESRI. 2000. ArcView version 3.2. Environmental Systems Research Institute, Inc.: Readlands, California.


For more information contact Jeannie Eidson