GEOGRAPHIC INFORMATION SYSTEMS
A GUIDE TO TERMINOLOGY
BASE MAP: A map containing a variety of features used for locational reference. Base maps typically
include streets, topography, boundaries and waterways, but can be customized to a client’s specific
needs.
CAD: Computer-aided design. An automated system used for drafting and design purposes.
(Also CADD: Computer-aided design drawing.)
COGO: Abbreviation of the term “coordinate geometry.”
DATA SET: A named collection of logically related data items arranged in a prescribed manner.
DATABASE: A logical collection of files managed as a unit.
DATABASE DEVELOPMENT: Procedures used in creating mapping modules and tiles. Examples include
data preparation, data input, processing and automation.
DIGITIZE: The process of tracing hard copy documents on a tablet to capture linework and locations of
map features in digital (computerized) form.
GEOGRAPHIC DATA: The locations and descriptions of geographic features, such as mountains or
waterways. Geographic data is the composite of spatial and descriptive data.
GEOGRAPHIC INFORMATION SYSTEM (GIS): An organized collection of computer hardware, software,
documentation and trained personnel designed to provide maximum utilization of the geographic data
pertaining to a specific region. Data can be stored, updated, manipulated, analyzed and displayed.
GEOREFERENCE: The placement of either raster or vector data into a referenced coordinate system. This
makes it possible to integrate the data from multiple data sets developed under the same coordinate
system, overlaying the different information for customized, composite purposes.
GRID: One of many data structures commonly used to represent map features. Data cells of equal size
are arranged in rows and columns. This structure is commonly used to store image data. (Also called
“raster.”)
LAYER: A logical set of thematic data, such as soils, land use, roads or waterways. One layer can be
placed atop another in various combinations in order to customize the view of an entire geographic area.
MODEL: A set of rules and procedures for conducting spatial analysis to derive new information to aid in
problem solving or planning. Models can include a combination of logical expressions, analytical
procedures and criteria in order to simulate a process, predict an outcome or characterize a
phenomenon.
MODULE: Standardized, non-overlapping geographic areas usually defined by base maps.
POLYGON: A polygon contains a label point inside its boundary and describes the geographic feature it
represents.
RASTER: One of many data structures commonly used to represent map features. Data cells of equal
size are arranged in rows and columns. This structure is commonly used to store image data. (Also
called “grid.”)
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A F F I L I A T E S
Remington, Vernick & Vena  Remington, Vernick & Walberg  Remington, Vernick & Beach  Remington, Vernick & Arango
GEOGRAPHIC INFORMATION SYSTEMS
A GUIDE TO TERMINOLOGY
SCANNING: The process of producing digital (computerized) images from hard copy format, via use of a
scanner.
SPATIAL DATA: Information regarding the location, shape and relationships among various geographic
features.
TAG: To create a unique identifier for each parcel represented in a GIS application. This will enable the
GIS to link with external tabular data.
TILE: The spatial unit by which geographic data is organized, subdivided and stored. A tile can be a
regular, geometric shape (such as a map sheet), or an irregular area, such as a regional boundary.
TOPOLOGY: The spatial relationship between adjacent or connecting coverage features. Can be used for
determining adjacency, containment or proximity of features in the data set.
VECTOR: A coordinate-based data structure commonly used to represent map features. Attributes are
associated with each individual feature, as opposed to a raster structure, which associates attributes
with a grid cell.
R E M I N G T O N
&
V E R N I C K
E N G I N E E R S
a n d
A F F I L I A T E S
Remington, Vernick & Vena  Remington, Vernick & Walberg  Remington, Vernick & Beach  Remington, Vernick & Arango