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GIS Glossary

aerial triangulation – The process of developing a network of horizontal and vertical position from a group of known positions using measurements taken from aerial photographs and mathematical computations.

attribute data – Characteristic or descriptive information about a geographic feature (points, lines, or areas) stored in either tabular format or relational format.

base map – A map containing geographic features, used typically for locational reference and for overlaying specific, discipline data.

coordinate system – A system to measure horizontal and vertical distances so that a geographic feature true position can be established in relation to an accepted public reference system such as State Plane or Universal Transverse Mercator (UTM) coordinate systems.

data formats – The specific patterns into which data are systematically arranged for use by a computer or specific software. There are both proprietary data formats and public-domain data formats.

Geographic Information System (GIS) – An organized collection of hardware, software, data, and personnel designed to input, analyze and display geographically referenced information.

GeoTIFF – A binary digital image format commonly used by GIS software that is characterized by reference information embedded in the file header as opposed to an external file.

Global Positioning System (GPS) – A satellite-based system for recording positional information and other data about a geographic feature. Ground positions are calculated by using signals from satellites orbiting the Earth.

ground control – Physical points on the ground whose positions are known with respect to some horizontal coordinate system and/or vertical datum. When identifiable on both the ground and an aerial photograph, ground control can be used to establish the true position of the aerial photograph.

hydrography – Geographic features that represent streams, lakes, reservoirs, rivers, and other drainage features.