Glossary of Planning and Geographic Information Systems (GIS) Terms

Glossary is usually defined as an alphabetical list of technical terms in some specialized field of knowledge. This knowledge base glossary provides a collection of knowledge base documents that define many technical terms. These terms are arranged alphabetically, but you can quickly jump to a specific term by selecting its first letter from the index of the knowledge base glossary below.

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Keyword

Term
Database Management System (Dbms)
A set of computer programs for organizing the information in a database. A DBMS supports the structuring of the database in a standard format and provides tools for data input, verification, storage, retrieval, query, and manipulation.
Datum
A set of parameters and control points used to accurately define the three-dimensional shape of the Earth (e.g., as a spheroid). The datum is the basis for a planar coordinate system. For example, the North American Datum for 1983 (NAD83) is the datum for map projections and coordinates within the United States and throughout North America.
Decibel "A" Weighted (Dba)
A measure of sound levels in average decibels usually over a 24-hour period calculated using a logarithmic average.
Density
The number of dwelling units or persons per acre of land, usually expressed in units per gross acre. * Single-family detached dwellings (range from less than 1 to 6 per acre) on a single lot. * Townhouses (range from 6 to 12 per acre) attached in a row. * Multifamily Apartments (range from 12 to 48 per acre) in one structure.
Developed Tier (As Defined By The 2002 General Plan)
The subarea of the county consisting primarily of inner-county areas that are largely developed. (See also DEVELOPING TIER and RURAL TIER.) See also:  Developing Tier, Rural Tier
Developing Tier (As Defined By The 2002 General Plan)
The largely suburban subarea of the county located primarily in the central portion of the county. (See also DEVELOPING TIER and RURAL TIER.) See also:  Developing Tier, Rural Tier
Development (As Defined In Zoning Ordinance)
Any activity that materially affects the condition or use of dry land, land under water, or any structure.
Digitize
1. To encode geographic features in digital form as x,y coordinates. 2. The process of using a digitizer to encode the locations of geographic features by converting their map positions to a series of x,y coordinates stored in computer files. Pushing a digitizer button records an x,y coordinate. A digitized line is created by recording a series of x,y coordinates.
Dissolve
The process of removing boundaries between adjacent polygons that have the same values for a specified attribute.
Domain
In a database, the set of allowed values for a table column, for example all positive integers.
Downzoning
A popular term for an action that changes a property to a lower density, in effect limiting development to less-intense uses than previously permitted.
Dwelling Unit
A room or group of rooms, occupied or intended for occupancy as separate living quarters.