GIS

GIS terms

1. "Digital Chart of the World" (DCW) (DCW) The first 1:1,000,000-scale digital basemap of the world. The DCW contains topologically based vector data digitized from the U.S.
2. ACCESS directory The system directory that LIBRARIAN uses to store the files that manage access to the library.
3. access rights The privileges accorded a user for reading, writing, deleting, updating and executing files on a disk.
4. accessibility An aggregate measure of how reachable locations are from a given location. The ACCESSIBILITY command computes values for accessibility as a function of…
5. accuracy, absolute The accuracy of a map in representing the geographic location of an object relative to its true location on the surface of the Earth.
6. accuracy, relative The accuracy of a map in representing the geographic location of an object relative to the locations of other objects.
7. Address Alias A place name which is associated with an address. Address Aliases include buildings names, historical monuments, educational facilities, and more.
8. Address Anomaly An address whose location is illogical. The address does not follow the standard rules of Washington, DC's addressing grid system.
9. address matching A mechanism for relating two files using address as the relate item. Geographic coordinates and attributes can be transferred from one address to the…
10. Address Point A map point over the location of an address. Multiple address points may exist within a lot.
11. Administrative and Other Boundaries Manmade legal boundary descriptions for the purpose of governance and management.
12. Advisory Neighborhood Commissions (ANC) (ANC) Bodies of local government in Washington DC. There are 37 ANCs. They consider a wide range of policies and programs affecting neighborhoods, including…
13. Aerial Photography The taking of photographs from the air with a camera mounted on an aircraft.
14. 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…
15. Air Rights Lots Air right lots are established by real property tax administration to reflect a party's right to construct an improvement above an existing area of land…
16. Allocation (1) An authorization by a designated official of a DoD component making funds available within a prescribed amount to an operating agency for the purpose…
17. American National Standards Institute (ANSI) (ANSI) A national coordinator of voluntary standards activities, and an approval organization and clearinghouse for consensus standards in the United States.
18. American Standard Code for Information Interchange (ASCII) (ASCII) A set of codes for representing alphanumeric information (e.g., a byte with a value of 77 represents a capital M).
19. Analysis A process in which anything complex is separated into simple or less complex parts.
20. annotation Adding pertinent information such as gene coded for, amino acid sequence, or other commentary to the database entry of raw sequence of DNA bases.
21. Application Program Interface (API) (API) An API is a set of system calls or routines for application programs to access services from operating systems or other programs.
22. Appropriations Refers to the process of divvying out water right allotments and beneficial uses within a water management district.
23. arc (1) Advanced Research Center, US Army, Huntsville, AL. (2) Atlantic Research Corporation.
24. Arc Attribute Table (AAT) (AAT) A table containing attributes for arc coverage features. In addition to user-defined attributes, the AAT contains the from and to nodes, the left and…
25. Arc Code (ACODE) file (ACODE) An INFO data file storing arc attributes for coverages created from TIGER, DIME, IGDS and Etak files. ACODE stands for 'Arc CODE'.
26. Arc Digitizing System (ADS) (ADS) A simple digitizing and editing system used to add arcs and label points to a coverage. A command at the Arc: prompt that starts an ADS session.
27. ARC Macro Language (AML) (AML) A high-level algorithmic language for generating end-user applications. Features include the ability to create on-screen menus, use and assign variables…
28. ARC Standard Raster Graphic (ASRG) (ASRG) Raster graphic data transformed to the Equal ARC-second Raster Chart/Map (ARC) Projection System. See SRG.
29. arc-node topology The topological data structure ARC/INFO uses to represent connectivity between arcs and nodes.
30. archive A copy of data (any information stored on a computer) on a computer drive, or on a portion of a drive, maintained for historical reference.
31. ArcStorm ArcStorm (ArcStorageManager) is a data storage facility and transaction manager for ARC/INFO data.
32. ArcStorm database An ArcStorm database is a collection of libraries, layers, INFO tables and external DBMS tables.
33. ArcTools ArcTools is a collection of ARC/INFO productivity tools implemented through an AML-based (ARC Macro Language) graphical user interface.
34. Area Must have legally defined geographical boundaries, and may be of any size, except that the site must be a subset of the U.S.
35. aspect The compass direction toward which a slope faces, measured in degrees from North in a clockwise direction.
36. attractiveness The property or properties of a location that create an incentive for trips to be made to that location.
37. attribute An attribute is a characteristic of data that sets it apart from other data, such as location, length, or type.
38. attribute data Characteristic or descriptive information about a geographic feature (points, lines, or areas) stored in either tabular format or relational format.
39. attribute table / DBMS table An INFO or other tabular file containing rows and columns. In ARC/INFO, attribute tables are associated with a class of geographic features, such as wells…
40. Automated Mapping and Facilities Management (AM/FM) (AM/FM) The management of mapping and facilities management using integrated computer software.
41. Azimuth A direction in terms of a 360° compass. North is at 0°, east is at 90°, south is at 180°, and west is at 270°.
42. Backup To create a copy of data as a precaution against the loss or damage of the original data.
43. band One layer of a multispectral image representing data values for a specific range of the electromagnetic spectrum of reflected light or heat (e.g.
44. band separate An image format that stores each band of data collected by multispectral satellite scanning instruments in a separate file.
45. Bandwidth The amount of information or data that can be sent over a network connection in a given period of time.
46. base map A map containing geographic features used for location reference. Roads, for example, are commonly found on base maps.
47. base table A table that is physically stored in the database. Compare with view.
48. Basemap The necessary GIS layers properly symbolized to create a common looking digital map of the District of Columbia.
49. Baud Rate The number of times per second a communications channel changes the carrier signal it sends on a phone line.
50. Binary large object (BLOB) (BLOB) The data type of a column in an RDBMS table which can store large image or textual data as attributes.
51. Bit A bit ( B inary dig IT ) is the smallest unit of computer data. A bit consists of either 0 or 1. There are eight bits in a byte.
52. BND The file in a coverage or grid which contains the coverage extent.
53. Boolean expression A type of expression that reduces to a true or false (logical) condition. A Boolean expression contains logical expressions (e.g.
54. border arcs The arcs that create the outer edge boundary of a polygon coverage. In LIBRARIAN, the tile boundary arcs that split a polygon coverage into tiles.
55. breakline A linear feature that defines and controls the surface behavior of a tin in terms of smoothness and continuity.
56. buffer A zone of a specified distance around coverage features. Both constant- and variable-width buffers can be generated for a set of coverage features based…
57. Bug A problem with computer software or hardware that causes it to malfunction or crash.
58. Business and Economic Development Economic activities or employment. For example, resources describing labor, revenue, commerce, industry, and specialized incentive areas.
59. byte Eight bits. A byte is a collection of bits used by computers to represent a character (i.e., "a", "1", or "&").
60. CAD drawing The digital equivalent of a drawing, figure or schematic created using a CAD system. For example, a drawing file or DWG file in AutoCAD.
61. cadastre Public record of the extent, value and ownership of land within a district for purposes of taxation.
62. Calibration the set of operations which establish, under specified conditions, the relationship between values indicated by a measuring instrument or measuring…
63. Capacity Your ability to make your mortgage payments on time. This depends on your income and income stability (job history and security), your assets and savings…
64. Cartesian Coordinate System A two-dimensional, planar coordinate system in which x measures horizontal distance and y measures vertical distance.
65. Cell The fundamental level of structural organization in complex organisms. Eukaryotic cells contain a nucleus (with chromosome s) and cytoplasm with the…
66. Center Generally speaking, the vertical axis of a tropical cyclone, usually defined by the location of minimum wind or minimum pressure.
67. character See: trait.
68. checkin Checkin is the act of returning ArcStorm data which was previously checked out for update purposes.
69. checkout Checkout is the act of taking selected data out of an ArcStorm database into a local coverage for editing purposes.
70. Citrix The server system that allows District employees to use applications such as ArcGIS and Pictometry software via the Intranet.
71. Client/Server An architecture whereby a computer system consists of one or more server computers and numerous client computers (workstations).
72. clip The spatial extraction of those features from one coverage that reside entirely within a boundary defined by features in another coverage (called the clip…
73. Column A vertical, cylindrical support. In classical design it is composed of a base (except in the Greek Doric order), a long, gradually tapered shaft, and a…
74. Comité Consultatif Internationale de Télégraphique et Téléphonique (Consultative Committee on International Telephone and Telegraph) (CCITT) CCITT is a technical committee of the International Telecommunications Union, a United Nations organization in Geneva.
75. command For command-oriented functions, the authorization required to perform command operations. 55
76. command line interface (CLI) (CLI) A software product that allows the user to type in commands at a prompt. Contrast to forms interface.
77. commit To send a person to prison, asylum or reformatory by a court order.
78. Compact Disk-Read Only Memory (CD-ROM) (CD-ROM) CD-ROM is an optical media. A CD-ROM 5.25-inch disk can hold about 650 megabytes of information.
79. Computer Aided Design (CAD) (CAD) An automated system for the design, drafting, and display of graphically oriented information.
80. Computer Graphics Metafile (CGM) (CGM) A graphic image exchange standard, ANSI: x3.122-1986, ISO: 8632-1986, for graphic output file format.
81. Computer-Aided Software Engineering (CASE) (CASE) CASE tools are defined programming rules for applying engineering principles, methods, techniques, and concepts.
82. concurrency management A database management process for maintaining consistency of the data while supporting simultaneous access by more than one user.
83. conditional operator A symbol or keyword specifying how to compare values. Conditional operators are used to query a database.
84. conflation A set of functions and procedures that aligns the arcs of one coverage with those of another and then transfers the attributes of one to the other.
85. connectivity The topological identification of connected arcs by recording the from- and to-node for each arc. Arcs that share a common node are connected.
86. constraints Limits imposed on a model. For example, in an interaction model, specifying that the number of trips generated from an origin to all destinations cannot…
87. Content Standards for Spatial Metadata (CSSM) (CSSM) A document produced by the Federal Geographic Data Committee (FGDC) that describes spatial metadata.
88. contiguity The topological identification of adjacent polygons by recording the left and right polygons of each arc. See also polygon-arc topology.
89. continuous data A surface for which each location has a specified or derivable value. Typically represented by a tin or lattice (e.g., surface elevation).
90. Contour A line of constant elevation.
91. contour interval The difference in surface values between contours.
92. contour line An imaginary line joining points of equal elevation.
93. Control Points Horizontal and Vertical: Small monuments securely embedded in the surface of the dam. Any movement of the monument indicates a movement in the dam itself.
94. coordinate A set of numbers that designate location in a given reference system, such as x,y in a planar coordinate system or an x,y,z in a three-dimensional…
95. COordinate GeOmetry (COGO) (COGO) Land surveyors use COGO functions to enter survey data, to calculate precise locations and boundaries, to define curves, and so on.
96. coordinate system A reference system used to measure horizontal and vertical distances on a planimetric map.
97. cover Natural or manmade objects on the bottom of lakes, rivers, or impoundments, especially those that influence fish behavior.
98. Cover-ID An integer identifier, assigned by the user, to relate geographic features and corresponding attribute data.
99. coverage The scope of protection provided by an insurance contract which includes any of the listed benefits in an insurance policy.
100. coverage extent The coordinates defining the minimum bounding rectangle (i.e., xmin,ymin and xmax,ymax) of a coverage or grid.