Glossary of GIS Terms - This is a short primer list, not all-encompassing

• Aspect - the viewing direction from or to an object, such as the southern aspect or view from a scenic overlook, and what would be seen from that aspect
• Attribute - any information related to a feature on a map; attributes for a wetland might be the classification (PEM), the area, perhaps related wildlife sightings - this will vary with the user and the project
• Coverage - used much the same as data layer; an example of a coverage is the road information or NWI information for any given area; may also be called a theme
• Digitize - to computerize (automate) mapped data by tracing it with a cursor (mouse) on a tablet equipped with an electronic grid for use in a GIS system
• Geo-referenced Data (geospatial) - mapped data tied to real-world geographic coordinates such as latitude and longitude
• GIS - geographic information system - a computerized system for linking and analyzing map data and related tabular data base information
• Grid Data - a type of GIS data consisting a rows and columns of square 'cells' or pixels, generally used for analysis purposes; each cell will have a value or classification assigned to it
• Data Layer - one piece of information in a geographic data base such as NWI - see coverage too
• Map Scale - a ratio of the units measured on the ground to each unit measured on the map; small scale = little detail, large area, small value of ratio such as 1:250,000); large scale = much detail, small area, large value of ratio such as 1:24,000)
• Metadata - data about data; if the data is the equivalent of a word in the dictionary, the metadata is the definition and history of the word
• Non-spatial Attribute - information related to an items that has no geographic information associated with it (e.g. the cost of a land parcel)
• Point - a feature on a map such as a nest that is a point location with no real area (acreage) involved
• Polygon - a mapped feature such as a wetland with curved or straight edges and area; used in vector coverages
• Raster - a type of data using grid cells rather than polygons; used especially for analysis, rather than display
• Spatial data - data that has a geographic relationship, or that can be mapped; may or may not be geo-referenced
• Vector - a type of data using polygons, points, and lines; gives a very realistic display or map , but not good for extensive modeling due to problems of exactly matching layers of data

For additional information regarding this Web page, contact Deb Southworth Green, in the Division of Information Resources and Technology Management, at Deb_Green@fws.gov

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Keywords=GIS, data, glossary
Last Modified January 02, 2001 12:08 PM