GIS — page 2 of 6

GIS terms

101. coverage units The units (e.g., feet, meters, inches) of the coordinate system in which a coverage is stored.
102. cross-tile indexing A method used to index features that cross tile boundaries. Features that cross tile boundaries are stored as one or more features in each tile instead of…
103. Cultural and Society The characteristics of societies and cultures. For example, resources describing natural settlements, anthropology, archaeology, traditional beliefs…
104. cursor A graphic pointer used with a mouse to point to a location on a terminal screen.
105. Cycle In alternating current, the current goes from zero potential or voltage to a maximum in one direction, back to zero, and then to a maximum potential or…
106. dangle length Minimum length allowed for dangling arcs during the CLEAN process. CLEAN removes dangling arcs that are shorter than the dangle length.
107. dangling arc An arc having the same polygon on both its left and right sides and having at least one node that does not connect to any other arc.
108. dangling node The endpoint of a dangling arcnot connected to another arc.
109. Data Access Language (DAL) (DAL) Apple's former standard to allow applications to communicate with relational databases. DAL is middleware on a network.
110. data access security Measures taken to control system users' ability to view or modify data. These measures can include logical views of data and explicit access rights by…
111. Data Base Management System (DBMS) (DBMS) Software that manages, manipulates and retrieves data in a database.
112. data conversion The translation of data from one format to another. ARC/INFO supports data conversion from many geographic data formats such as DLG, TIGER, DXF, and DEM.
113. Data definition language (DDL) (DDL) SQL statements that can be used either interactively or within programming language source code to define databases and their components.
114. data dictionary A catalog of all data held in a database, or a list of items giving data names and structures. Also referred to as DD/D for data dictionary/directory.
115. Data Exchange Format (DXF) (DXF) A format for storing vector data in ASCII or binary files. Used by AutoCAD and other CAD software for data interchange.
116. Data Formats The organization of information for display, storage or printing. Data is maintained in certain common formats so that it can be used by various programs…
117. Data Integrity The state that exists when computerized data is the same as that in the source documents and has not been exposed to accidental or malicious alteration or…
118. Data manipulation language (DML) (DML) SQL statements that can be used either interactively or within programming language source code to access and retrieve data stored in a database…
119. data model The result of the conceptual design process. A generalized, user-defined view of the data related to applications.
120. data set A named or defined collection of data. See also Production Data Set and Privilege Data Set.
121. data type The type of information that one field can store, for example, text, rich text, numbers, keywords, and time.
122. database In electronic records a database is a set of data elements consisting of at least one file, or of a group of integrated files, usually stored in one…
123. database design The formal process of analyzing facts about the real world into a structured database model.
124. DATABASE directory The same as the Library Reference workspace. It is the system directory that LIBRARIAN uses to manage information about a map library.
125. Database integrator (DBI) (DBI) ARC/INFO software's link to relational database management systems (RDBMS). DBI enables ARC/INFO users to access existing commercial databases and take…
126. database lock Locking is a mechanism by which database systems can prevent conflicting access to data when multiple users are making requests to the data.
127. database management system (DBMS) (DBMS) A software system used to access and retrieve data stored in a database.
128. datum Any level surface taken as a plane of reference from which to measure elevations.
129. DC GIS Refers to all the hardware, software, and databases that provide the central GIS functionality for the District of Columbia government.
130. Demand Form PCT/IPEA/401, filed with an International Preliminary Examining Authority, demanding that an international application shall be the subject of an…
131. Demographic Related to the vital statistics of human populations (size, density, growth, distribution, etc.) and the effect of these on social and economic conditions.
132. denormalization The process of restructuring a normalized data model to accommodate operational constraints or system limitations.
133. densify A process of adding vertices to an arc at specified distances, without altering the arc's shape. Compare with spline and grain tolerance.
134. descriptive data Tabular data describing the characteristics of geographic features. Can include numbers, text, images, and CAD drawings about features.
135. destination In spatial interaction, the location of the end of a trip. For example, a shop or an office where a consumer or a worker is going.
136. Detailed Metadata This metadata satisfies the requirements of the Federal Geographic Data Committee (FGDC), as augmented by additional elements defined by ESRI.
137. Differential Global Positioning System (DGPS) (DGPS) A positioning procedure that uses two receivers, a rover at an unknown location and a base station at a known, fixed location.
138. Digital Elevation Model (DEM) (DEM) A digital representation of a continuous variable over a two- dimensional surface by a regular array of z values referenced to a common datum.
139. Digital Geographic Information Exchange Standard (DIGEST) (DIGEST) produced under authority of NATO's Digital Geographic Information Working Group.
140. Digital Geospatial Metadata (DGM) (DGM) DGM was approved in June 1994 by the Federal Geographic Data Committee (FGDC). DGM describes the specifications for the content, quality, condition, and…
141. Digital Line Graph (DLG) (DLG) Digital Line Graph files from the U.S. Geological Survey (USGS), including data from the base map categories such as transportation, hydrography…
142. digital map library A series of directories and subdirectories designed to uniformly organize a collection of spatial data.
143. Digital Terrain Model (DTM) (DTM) See digital elevation model.
144. digitize The process of converting an analog value into a digital (numeric) representation.
145. digitizer Device that converts analog information into a digital format; for flat graphic material, such as maps, a digitizer can either be flatbed or scanning.
146. digitizing See digitize.
147. directed network A network in which each arc has an associated direction of flow. Direction of flow can be determined by arc direction (e.g.
148. Directory A simulated file folder or container used to organize files and directories in a hierarchical or tree-like structure.
149. discrete data Geographic features containing boundaries: point, line or area boundaries.
150. disk The visible surface of the sun (or any heavenly body) projected against the sky.
151. diskette An inexpensive, low-capacity storage medium, usually measuring 3.5 inches in diameter, often referred to as a floppy disk.
152. dissolve To enter into a solution.
153. distance-decay function In spatial interaction, the mathematical representation of the effect of distance on the accessibility and number of interactions between locations.
154. Domain A sub-network of servers and computers within a LAN. Domain information is useful when restoring backup tapes, particularly of email.
155. double precision Refers to a high level of coordinate accuracy based on the possible number of significant digits that can be stored for each coordinate.
156. downstream The region extending in a 3' direction from a gene.
157. drape A perspective or panoramic rendering of two-dimensional features superimposed on a surface.
158. Dynamic Data Exchange (DDE) (DDE) An IAC protocol developed by Microsoft for Windows-based applications. DDE allows one application to send messages to, and get information from, other…
159. dynamic segmentation The process of computing the locations of events on linear features at run time based on event tables for which distance measures are available.
160. Earth Observation Satellite (EOS) (EOS) An effort to study the earth as a system while tracking long-term changes on a global scale.
161. edge matching An editing procedure to ensure that all features that cross adjacent map sheets have the same edge locations.
162. edit To correct errors within, or modify, a computer file, a geographic data set, or a tabular file containing attribute data.
163. Education Formal education information. For example, schools, universities, colleges, and related activities.
164. Elevation A drawing of a face of a building with all the features shown, as if in a single vertical plane
165. embedded SQL SQL statements that are embedded in a host language program.
166. entity A legally recognized organization.
167. entity relationship diagram A graphical representation of the entities and the relationships between them. Entity relationship diagrams are a useful medium to achieve a common…
168. Environment All the natural and living things around us. The earth, air, weather, plants, and animals all make up our environment.
169. equation item An arithmetic expression used in place of an itemname in an ARC/INFO command. For example, to list feature areas, a user could specify LIST AREA; to list…
170. Equator The parallel of reference 0 north or south.
171. Ethernet A common way of networking PCs to create a LAN.
172. event In LotusScript, an action or occurrence to which an application responds. That action can be a user-generated one, such as a mouse click; a…
173. event source This is a name assigned by the user to reference a DBMS table containing event data for use with the dynamic segmentation commands.
174. extended character set Extended character sets support languages which require 8-bit characters or double-byte characters, such as Chinese and French.
175. external file INFO stores data in files within a database. However, database information can be stored in files outside of the database.
176. external polygon See universe polygon.
177. Facility and Structure Manmade construction. For example, resources describing buildings, fences, and related items.
178. feature attribute table A table used to store attribute information for a specific coverage feature class. ARC/INFO maintains the first several items of these tables.
179. feature class A collection of geographic features with the same geometry type (such as point, line or polygon), the same attributes, and the same spatial reference.
180. feature selection by attribute See logical selection.
181. Feature-ID Synonymous term for Cover-ID and User-ID.
182. Federal Geodetic Control Committee (FGCC) (FGCC) a standards committee concerned with accuracy levels in geodetic control. Within the United States, coordinate control is based on the National Geodetic…
183. Federal Information Processing Standards (FIPS) (FIPS) FIPS deals with a wide range of computer system components including the components of most GISs: hardware, storage media, data files, codes, interfaces…
184. Fiber Distributed Data Interface (FDDI) (FDDI) A media access (transmission) control-level protocol with token-ring architecture, a communication bandwidth of 100 Mbps and supported on a fiber network…
185. field Field A region of space at each point of which a given physical or mathematical quantity has some definite value.
186. field data collector An electronic device that collects and stores observation information from survey instruments.
187. Field Research The gathering and research of information at the physical location; as opposed to research or information gathering in the office.
188. file To place a paper in the official custody of the clerk of court/court administrator to enter into the files or records of a case.
189. file transfer Moving named files from one computer or network to another
190. font A logical set of related patterns representing text characters or point symbols. Courier, Helvetica and Times are three types of font.
191. foreign key One or more table attributes that can uniquely identify a record in another table. A foreign key is the primary key of another table.
192. Format The internal structure of a file, which defines the way it is stored and used. Specific applications may define unique formats for their data (i.e.
193. forms interface A graphic user interface characterized by user-controlled movement of a cursor from one data field to another. Contrast to command line interface.
194. from-node Of an arc's two endpoints, the one first digitized.
195. functional surface A surface representation which stores a single z value (as opposed to multiple z values) for any given x,y location.
196. fuzzy tolerance The fuzzy tolerance is an extremely small distance used to resolve inexact intersection locations due to limited arithmetic precision of computers.
197. Gazetteer A geographical dictionary, an important reference for information about places and place-names and associated spatial location
198. GBF/DIME For the 1980 census, the U.S. Census Bureau produced Geographic Base Files (GBF) and Dual Independent Map Encoding (DIME) files, containing census…
199. generalization In general, reducing the number of points used to represent a line. In ARC/INFO, the process of removing vertices from arcs according to a specified…
200. geocode Geocode refers to the combination of applicable codes for the metropolitan area, state, county and census tract.