-- Terms Beginning with a Number --
Term Definition/Description Source
11/10 peg adjustment See peg adjustment. HDBK-850
24-hour satellite See synchronous satellite. HDBK-850
497th Intelligence Group The 497th IG, located at Bolling Air Force Base, Washington, D.C., provides specialized intelligence services to Headquarters United States Air Force (USAF) and other U.S. Air Force units worldwide. The group provides tailored intelligence assessments in support of Air Staff planning and policy formulation: monitoring, analyzing and reporting on hostile action against the United States and its allies. The organization also provides functional management for all Air Force targeting issues and for all U.S. Air Force sensitive compartmented information (SCI) security functions. USAF Web Site
544th Intelligence Group The 544th IG, headquartered at Peterson Air Force Base, Colo., provides intelligence and information to Air Force Space Command (AFSPC). The group was established to provide a single focal point for continental U.S. based operational space issues and to posture the Air Intelligence Agency (AIA) to better support AFSPC and national agencies. USAF Web Site
67th Intelligence Wing The 67th IW, headquartered at Kelly Air Force Base, Texas, manages the Air Intelligence Agency's (AIA) global mission. The wing manages the planning of all-source intelligence, information warfare and security support. It assists United States Air Force (USAF) components in the development of concepts, exercises and employment of AIA forces to support low-intensity conflict, counterdrugs and special operations as AIA's integrated wing. Subordinated to the wing are four intelligence groups located in the continental U.S., Hawaii and Germany. USAF Web Site
-- A --
Term Definition/Description Source
ABAC A nomogram for obtaining the conversion angle to apply when plotting great-circle bearings on a Mercator projection. HDBK-850
abnormal magnetic variation Any anomalous deflection, whose cause is unknown, of the compass needle from the magnetic meridian. HDBK-850
abscissa The horizontal coordinate of a set of rectangular coordinates. Also used in a similar sense in connection with oblique coordinates. Also called total departures; x-coordinate. HDBK-850
absolute accuracy Absolute accuracy is defined as the statistic which gives the uncertainty of a point with respect to the datum required by a product specification. This definition implies that the effects of all error sources, both random and systematic, must be considered. Absolute accuracy is stated in terms of two components, a horizontal compontent and a vertical component. The horizontal absolute accuracy associated witha product is stated as circular error, CE, such that 90 percent of all positions depicted by that product have a horizontal error with magnitude less than CE. Likewise, the absolute vertical accuracy associated with a product is stated as a linear error, LE, such that 90 percent of all elevations depicted by the product have an error with magnitude less than LE. MIL-STD-600001
absolute error Absolute deviation, the value taken without regard to sign, from the corresponding true value. HDBK-850
absolute gravity The acceleration of gravity directly determined by a device that measures time and length. See also gravity. HDBK-850
absolute gravity station A marked point, usually in a laboratory, where the value of absolute gravity has been determined. See also absolute gravity. HDBK-850
absolute orientation The scaling and leveling to ground control (in a photogrammetric instrument) of a relatively oriented stereoscopic model or group of models. See also relative orientation. HDBK-850
absolute parallax See absolute stereoscopic parallax. HDBK-850
absolute positioning Determination of the position of a point with respect to the center of mass of the Earth as defined in the DoD World Geodetic System. HDBK-850
absolute stereoscopic parallax Considering a pair of aerial photographs of equal principal distance, the absolute stereoscopic parallax of a point is the algebraic difference of the distances of the two images from their respective photograph nadirs, measured in a horizontal plane and parallel to the air base. Also called absolute parallax; horizontal parallax; linear parallax; parallax; stereoscopic parallax; x-parallax. HDBK-850
absolute term A term (usually only one) in an equation, which represents a known numerical value and does not contain any unknown or variable elements. HDBK-850
absolute unit Any unit in a system that is based directly upon associated fundamental units of length, mass, and time. See also dynamic number. HDBK-850
absolute value A mathematical quantity taken without regard to its associated plus or minus sign. Used often with residuals. HDBK-850
absolute vector A directed line segment whose end points are measured in absolute units from a point designated as the origin. HDBK-850
absorption Conversion of radiant energy into other forms by passage through or reflection from matter. HDBK-850
abstract data type A combination of basic data types. CEN/TC 287
abstract universe A subset of perceived reality. NOTE - A particular abstract universe is perceived within the context of each geographic information application. ISO/TC 211
abstraction The process of suppressing irrelevant detail to establish a simplified model, or the result of that process. RM-ODP
acceleration 1. The rate of change of velocity. 2. The act or process of accelerating, or the state of being accelerated. HDBK-850
acceleration of gravity The acceleration of a freely falling body, approximately 9.8m/sec2. HDBK-850
accelerometer 1. A device that measures the rate of change of speed of an object. 2. An instrument, specially designed for carrying in aircraft or missiles, which measures the rate of change in velocity, direction, and/or altitude. HDBK-850
Acceptable Level of Risk {AIS Security} A judicious and carefully considered assessment by the appropriate accrediting authority that the value of the automated information system (AIS) or network unambiguously outweighs the likelihood of potential damage to the security interests of the United States in the event information from the system is compromised, damaged, or destroyed. The severity of the potential damage must be taken into account. The assessment should take into account the value of AIS or network assets, threats, and vulnerabilities, as well as countermeasures and their ability to compensate for vulnerabilities and operational requirements. [DISA/D2] DISA CFS
acceptable quality level The threshold quality level by which data producers determine the acceptance of geospatial data set based on product specification. ISO/TC 211
access The ability of an imaging system to acquire a specific target at the user-specified desired parameters. USIS 95
access cone The field of view (defined by minimum elevation, maximum obliquity and/or maximum slant range) of the imaging platform at a particular instant. USIS 95
access control Process of limiting access to the resources of an IT product only to authorized users, programs, processes, systems, or other IT products. JTA 2.0
access frequency The time between successive accesses to a target. The minimum time between possible collections. USIS 95
access swath An access swath includes all places on the Earth's surface within defined access viewing constraints as the imaging platform moves along. USIS 95
access time lag The amount of time from receipt of an imaging request to the next valid imaging opportunity. USIS 95
Access Transparency A distribution transparency which masks differences in data representation and invocation mechanisms to enable interworking of objects. RM-ODP
accidental error See random error. HDBK-850
accommodation 1. The ability of the human eye to adjust itself to give sharp images of objects of different distances. In stereoscopy, the ability of the human eyes to bring two images into superimposition for stereoscopic viewing. 2. The limits or range within which a stereoplotting instrument is capable of operating. For example, the multiplex can adjust (or accommodate) for small tilts in the projectors ranging from approximately 10 about the x-axis to 20 about the y-axis. HDBK-850
accomplishments to requirements ratio A numeric ratio of accomplishments to requirements that indicates the portion of the requirement that has been satisfied. USIS 95
Account Group {DII COE} A template for establishing a runtime environment context for individual operators. Account groups are typically used to do a high-level segregation of operators into system administrators, security administrators, database administrators, or mission-specific operators. DII COE IRTS
accreditation A formal declaration by the Designated Approving Authority (DAA) that the Automated Information System (AIS) is approved to operate in a particular security mode by using a prescribed set of safeguards. Accreditation is the official management authorization for operation of an AIS and is based on the certification process as well as other management considerations. The accreditation statement affixes security responsibility with the DAA and shows that due care has been taken for security. [DISA/D2] DISA CFS
accreditation The managerial authorization and approval, granted to an ADP system or network to process sensitive data in an operational environment, made on the basis of a certification by designated technical personnel of the extent to which design and implementation of the system meet pre-specified technical requirements, e.g., TCSEC, for achieving adequate data security. Management can accredit a system to operate at a higher/lower level than the risk level recommended (e.g., by the Requirements Guideline) for the certification level of the system. If management accredits the system to operate at a higher level than is appropriate for the certification level, management is accepting the additional risk incurred. JTA 2.0
accreditation body A body that conducts and administers laboratory accreditation and grants accreditation. ISO/TC 211
accredited standards development organization An organization recognized as a standards development organization by ISO, IEC, ITU-T, or recognized as a standards development organization by one of the member bodies of one of these three organizations. IEEE P1003.0
accumulated discrepancy The algebraic sum of the separate discrepancies which occur in the various steps of making a survey or of the computation of a survey. HDBK-850
accumulated divergence (leveling) The algebraic sum of the divergences for the sections of a line of levels, from the beginning of the line to any section end at which it is desired to compute the total divergence. HDBK-850
accumulative error See systematic error. HDBK-850
accuracy 1. The degree of conformity with a standard, or the degree of perfection attained in a measurement. Accuracy relates to the quality of a result, and is distinguished from precision, which relates to the quality of the operation by which the result is obtained and can be repeated. 2. The closeness of the best estimated value obtained by the measurements to the "true" value of the quantity measured. HDBK-850
accuracy The closeness of results of observations, computations or estimates to the true values or the values accepted as being true. NOTE - Often takes the form of a measure of probable error. ISO/TC 211
accuracy The degree to which information on a map or in a digital database matches true or accepted values. Accuracy pertains to the quality of data and the number of errors contained in a dataset or map. In discussing a GIS database, it is possible to consider horizontal and vertical accuracy with respect to geographic position, as well as attribute, conceptual, and logical accuracy. The effect of inaccuracy and error on a GIS solution is the subject of sensitivity analysis. Accuracy, or error, is distinguished from precision , which concerns the level of measurement or detail of data in a database. OpenGIS Guide
accuracy checking The procurement of presumptive evidence of a map's compliance with specified accuracy standards. Accuracy checking generally indicates the relative (rather than the absolute) accuracy of map features. HDBK-850
accuracy evaluation The comparison of the quality of an MC&G product with maintenance criteria to ascertain its adequacy with respect to its intended use. HDBK-850
accuracy method The method used in determining the stated accuracy of a product. The method can range from a system employing highly sophisticated techniques to a highly subjective judgment, and is essential for proper use of the stated accuracy. HDBK-850
accuracy review The comparison of an existing MC&G product against source material or data more accurate than that from which it was produced, for the purpose of determining the accuracy of its horizontal and vertical values. HDBK-850
accuracy testing The procurement of confirmed evidence, on a sampling basis, of a map's compliance with specified accuracy standards. Accuracy testing is designed to indicate both the relative and absolute accuracy of map features. HDBK-850
accurate contour A contour line, the accuracy of which lies within one-half of the basic vertical interval. Also called normal contour. HDBK-850
achromatic color Color that does not elicit hue. HDBK-850
achromatic lens A lens that has been partly corrected for chromatic aberration. Such a lens is usually of a multi-element design to bring green and red light rays to approximately the same point of focus. HDBK-850
acoustic intelligence (ACINT) (DOD, NATO) Intelligence derived from the collection and processing of acoustic phenomena. JPUB 1-02
acoustic intelligence (ACINT) One of several "INTS" that are part of MASINT. Intelligence information derived from analysis of acoustic waves radiated either intentionally or unintentionally by the target into the surrounding medium. USIS 95
acoustic navigation Navigation by means of sound waves whether or not they are within the audible range. Also called sonic navigation. See also Doppler sonar navigation. HDBK-850
acquisition categories {DoD} Part of the DoD 5000.1 program for determining the need for, and funding of, new systems. See also research and development (R&D) categories {DoD}. USIS 95
acquisition executive {DoD} The individual, within the [DoD] and Components, charged with overall acquisition management responsibilities within his or her respective organizations. The Undersecretary of Defense (Acquisition and Technology) is the Defense Acquisition Executive (DAE) responsible for all acquisition matters within the Department of Defense. The Component Acquisition Executives (CAEs) for each of the Components are the Secretaries of the Military Departments or Heads of Agencies with power of redelegation. The CAEs, or designee, are responsible for all acquisition matters within their respective Components. DoDD 5000.1
acquisition phase {DoD} All the tasks and activities needed to bring a program to the next major milestone occur during an acquisition phase. Phases provide a logical means of progressively translating broadly stated mission needs into well defined system-specific requirements and ultimately into operationally effective, suitable, and survivable systems. An example of an acquisition phase is Program Definition and Risk Reduction. DoDD 5000.1
acquisition program {DoD} A directed, funded effort that is designed to provide a new, improved, or continuing weapons system or automated information system (AIS) capability in response to a validated operational need. Acquisition programs are divided into categories, which are established to facilitate decentralized decision-making and execution and compliance with statutory requirements. DoDD 5000.1
actinic light Light which is capable of causing photochemical changes in a sensitized emulsion. HDBK-850
activation Preparing an object to execute an operation. For example, copying the persistent form of methods and stored data into an executable address space to allow execution of the methods on the stored data. CORBA 2.2
active remote sensing Remote sensing methods that provide their own source of electromagnetic radiation from which to measure returns. Radar is one example. USIS 95
active satellite A satellite which transmits an electromagnetic signal. A satellite with the capability to transmit, repeat, or retransmit electromagnetic information. See also passive satellite. HDBK-850
active thermal emissions See emitted radiance and reflected radiance. USIS 95
active tracking system A satellite tracking system which operates by transmission of signals to and receipt of responses from the satellite. HDBK-850
activity (TAP) A mission function or business process performed by an organizational node. NIMA/AR
activity A single-headed directed acyclic graph of actions, where the occurrence of each action in the graph is made possible by the occurrence of all immediately preceding actions (i.e. by all adjacent actions which are closer to the head). RM-ODP
Activity Hierarchy The activity hierarchy describes the activities associated with specific tasks, the relationship among the activities, and the decomposition of the tasks. C4ISR AF
Activity Model Describes the applicable activities associated with the architecture, the data and/or information exchanged between activities, and the data and/or information exchanged with other activities that are outside the scope of the model. C4ISR AF
activity model {IDEF0} A graphic description of a system or subject that is developed for a specific purpose and from a selected viewpoint. A set of one or more IDEF0 diagrams that depict the functions of a system or subject area with graphics, text and glossary. (FIPS Pub 183, Integration Definition For Function Modeling (IDEF0), December 1993). JTA 2.0
actual error The difference between the true value and the measured value of a physical quantity. HDBK-850
acutance An objective measure of the ability of a photographic system to show a sharp edge between contiguous areas of low and high illuminance. HDBK-850
ad hoc nomination A request for imagery or imagery-derived information for short-term and immediate problems. USIS 95
ad hoc requirement A collection requirement developed on an ad hoc basis and usually having the following characteristics: short-term duration; specific beginning and end dates; current significance not likely to be satisfied through the planned sampling process; and unique imaging considerations. See standing requirement. USIS 95
Ada Ada is a programming language designed to support the construction of long-lived, highly reliable software systems. Ada JPO Web Site
adaptation The faculty of the human eye to adjust its sensitivity to varying intensities of illumination. HDBK-850
adapter Same as object adapter. CORBA 2.2
Adaptive Dynamic Range Adjustment (ADRA) Automatically adjusts contrast and brightness for varying image conditions. USIS 95
additive color mixture Superimposition or other nondestructive combination of light of different chromaticities. HDBK-850
additive color viewer Projector for positive transparencies obtained through multiband photography. Each image is superimposed by use of a different colored light. HDBK-850
additivity of luminance Luminance produced with a mixture of light from several sources is the sum of the luminances produced by the light from lack of the sources acting separately. HDBK-850
address indicator group Used to combine addresses for message/cable traffic. USIS 95
adjacency A topological property which provides relationships between objects which abut or are located in close proximity. Also known as contiguity. HDBK-850
adjoining sheets Adjacent maps to one or all sides and corners of a particular map sheet. HDBK-850
Adjusted Mapping Support Data (AMSD) The post-mission refined version of those parameters used to position collector platforms, sensors, and sensor pointing angles. HDBK-850
adjusted value A value of a quantity derived from observed data by some orderly process which eliminates discrepancies arising from errors in those data. HDBK-850
adjustment 1. (general) The determination and application of corrections to observations, for the purpose of reducing errors or removing internal inconsistencies in derived results. The term may refer either to mathematical procedures or to corrections applied to instruments used in making observations. 2. (leveling) The determination and application of corrections to orthometric differences of elevation or to orthometric elevations, to make the elevation of all bench marks consistent and independent of the circuit closures. 3. (cartography) Placing detail or control stations in their positions relative to other detail or control stations. See also adjustment of observations; angle method of adjustment; balancing a survey; direction method of adjustment; figure adjustment; instrument adjustment; land-line adjustment; least squares; map adjustment. HDBK-850
adjustment of observations The determination and application of corrections corresponding to errors affecting the observations, making the observations consistent among themselves, and coordinating and correlating the derived data. HDBK-850
administrative map (JCS) A map on which is graphically recorded information pertaining to administrative matters, such as supply and evacuation installations, personnel installations, medical facilities, collecting points for stragglers and prisoners of war, train bivouacs, service and maintenance areas, main supply roads, traffic circulation, boundaries, and other details necessary to show the administrative situation. See also map. HDBK-850
Adopted Non-Government Standard A non-Government standard that has been accepted for use by the DOD and is listed in the DOD Index of Specifications and Standards (DODISS). (DOD 4120.3-M) DISA CFS
Adopting Activity The activity responsible for the adoption of a non-Government standard. [DOD 4120.3-M] DISA CFS
Advanced Along-Track Scanning Radiometer (AATSR) An imaging radiometer which provides precise measurements of sea surface temperatures. Applications are being developed for land monitoring. Data are collected continuously in four infra-red (IR) channels and four visible channels. Various viewing directions are available. The AATSR is on-board the European Polar Platform. CCRS Glossary
Advanced Applications Development Cell An organization, located in the National Exploitation Laboratory, dedicated to validating MASINT techniques. CIO [now part of NIMA], Central MASINT Office, each System Program Office and NPIC [now part of NIMA] have permanent seats on the Steering Group. Every organization that supplies a member of the AADC staff has a seat on the Steering Group as long as that organization supplies a person to the effort. USIS 95
Advanced Civil Earth Remote Sensing System A National Oceanic and Atmospheric Administration satellite. USIS 95
Advanced Imagery Requirements and Exploitation System (AIRES) Life Extension (ALE) A replacement for the Advanced Imagery Requirements and Exploitation System (AIRES). Provides imagery research support, and imagery indexing. ALE will be a Defense Intelligence Agency (DIA) system and will be available over the Secure Internet Protocol Router Network (SIPRNET). USIS 95
Advanced Interoperability {DII COE} A level of interoperability characterized by shared data between applications, including shared data displays, and information exchange through a common data model. This level provides for sharing of information in a distributed, but localized environment, and for sharing of applications. DII COE IRTS
Advanced Research Projects Agency Network (ARPANET) A communications network developed as part of a research and development project to connect scientists sponsored by ARPA. USIS 95
Advanced Spaceborne Thermal Emission and Reflection Radiometer A joint NASA/Japan 15- to 90-meter resolution satellite for imaging land and clouds for climatology, hydrology, biology and geology. Funded by the Ministry of International Trade and Industry for the Geological Survey of Japan. USIS 95
Advanced Synthetic Aperture Radar System-2 A high-resolution, day/night, all-weather synthetic aperture radar flown aboard the U-2R. USIS 95
Advanced Tactical Air Reconnaissance System (ATARS) An advanced integrated reconnaissance suite. A joint Air Force, U.S. Navy, USMC project. The Joint Service Imagery Processing System (JSIPS) is the ground processing system and together with ATARS makes up the Follow-On Tactical Air Reconnaissance system (FOTARS). USIS 95
Advanced Very High Resolution Radiometer (AVHRR) A five band scanning radiometer that operates in the visible, near-infrared, and thermal-infrared regions with low spatial resolution (1 kilometer). AVHRR was designed as a meteorological sensor to image both cloud cover and ocean phenomena. Terrestrial applications include tropical forest monitoring, fire risk assessment and biophysical parameter estimation. Data is down linked in real-time, line-of-sight mode and is stored for down link over remote stations. AVHRR provides daily world-wide coverage. USIS 95
Advanced Visible and Near-infrared Radiometer A Japanese sensor containing three visible and a single near-infrared band complemented by a panchromatic visible band with 8-meter resolution. Will be on the Advanced Earth Observation Satellite (ADEOS). USIS 95
Advanced Weapons and Systems Data Base (AWSDB) A NIMA relational data base used to assess and consolidate the MC&G product requirements for fielded, new, and emerging DoD weapons and systems. HDBK-850
aerial camera A camera specifically designed for use from an airborne station. HDBK-850
aerial cartographic photography See mapping photography. HDBK-850
aerial film Specially designed roll film supplied in many lengths and widths, with various emulsion types for use in aerial cameras. HDBK-850
aerial film speed (AFS) A measure of speed for aerial film which replaces the formerly used aerial exposure index. It is defined as 3/2E, where E is the exposure in meter-candle-seconds at the point on the characteristic curve where the density is 0.3 above base plus fog density on black-and-white film. HDBK-850
aerial imagery Any remotely-sensed nonphotographic image taken from the air (as opposed to space). HDBK-850
Aerial Imagery Reconnaissance Tracking and Plotting System (AIRTAPS) The AIRTAPS is an exportable PC based system that gives members of the counternarcotics community the capability to manage aerial collection against counternarcotics targets worldwide. The system supports the display of mission and target data over a geographical (map) display. AIRTAPS
aerial mosaic See mosaic, definition 1. HDBK-850
aerial photogrammetry The use of aerial photographs in the science of photogrammetry. HDBK-850
aerial photograph Any photograph taken from the air. Also called air photograph. HDBK-850
aerial photographic reconnaissance The obtaining of information by aerial photography-divided into three types: (1) strategic photographic reconnaissance; (2) tactical photographic reconnaissance; and (3) survey/cartographic photography, which is aerial photography taken for survey/cartographic purposes and to survey/cartographic standards of accuracy. HDBK-850
aerial photography The art, science, or process of taking aerial photographs. See also mapping photography; reconnaissance photography. HDBK-850
aerial platform A term referring to the support of an aerial camera at the air station. HDBK-850
aerial reconnaissance The collection of information by visual, electronic, photographic, or other means from the air. HDBK-850
aerial survey A survey utilizing photographic, electronic, or other data obtained from an airborne station. HDBK-850
aerial triangulation See phototriangulation. HDBK-850
aerodetic (JCS) Of or pertaining to, or determined by aerodesy. HDBK-850
aeroleveling As applied to model orientation during phototriangulation, barometric height measurements of the camera air stations which have been recorded during the photographic mission are used to present the Bz values during the orientation of the successive models on the stereoplotting instrument. Only differences in altitude are required and these are provided by the statoscope. See also orientation, definition 7. HDBK-850
aerometeorograph An instrument that records the pressure and temperature of the air, the amount of moisture in the air, and the rate of motion of the wind. HDBK-850
aeronautical chart (JCS) A specialized representation of mapped features of the Earth, or some part of it, produced to show selected terrain, cultural, and hydrographic features, and supplemental information required for air navigation, pilotage, or for planning air operations. Also called navigation chart. HDBK-850
Aeronautical Data Maintenance (ADM) A production element of NIMA's DPS which involves the processes of collecting, compiling, and updating. See also Digital Production System (DPS). HDBK-850
aeronautical information overprint (JCS) Additional information which is printed or stamped on a map or chart for the specific purpose of air navigation. HDBK-850
aeronautical pilotage chart An aeronautical chart designed primarily for air navigation. HDBK-850
aeronautical planning chart An aeronautical chart of small scale designed to satisfy long-range air navigation and mission planning requirements. HDBK-850
aeropause (JCS) Region in which functional effects of the atmosphere on man and aircraft cease to exist. HDBK-850
aerospace (JCS) Of, or pertaining to, the Earth's envelope of atmosphere and the space above it; two separate entities considered as a single realm for activity in launching, guidance, and control of vehicles which will travel in both entities. HDBK-850
aerotriangulation See phototriangulation. HDBK-850
Affected Account Group(s) {DII COE} The account group(s) to which a segment applies. Functionality provided by the installed segment will normally appear to the operator as new menu items or icons in the affected account group(s). DII COE IRTS
affine deformation One in which the scale along one axis or reference plane is different from the scale along the other axis or plane. HDBK-850
affine transformation A transformation in which straight lines remain straight and parallel lines parallel. Angles may undergo changes and differential scale changes may be introduced. HDBK-850
Afloat Planning System Supports Tomahawk mission data planning for Tomahawk land-attack missiles (TLAM). USIS 95
age of diurnal inequality The time interval between the maximum semimonthly north or south declination of the Moon and the time that the maximum effect of the declination upon the range of tide or speed of the tidal current occurs. Also called age of diurnal tide; diurnal age. HDBK-850
age of diurnal tide See age of diurnal inequality. HDBK-850
age of parallax inequality The time interval between the perigee of the Moon and the maximum effect of the parallax (distance of the Moon) upon the range of tide or speed of tidal current. Also called parallax age. HDBK-850
age of phase inequality The time interval between the new or full Moon and the maximum effect of these phases upon the range of tide or speed of tidal current. Also called age of tide; phase age. HDBK-850
age of the Moon The elapsed time, usually expressed in days, since the last new Moon. HDBK-850
age of tide See age of phase inequality. HDBK-850
agent An activity which acts for, and by authority of, the Preparing Activity or Adopting Activity in the preparation of standardization documents, item reduction studies, engineering practice studies, and the administration of Qualified Products Lists (QPLs) and Qualified Materials Lists (QMLs). The Preparing Activity retains responsibility and approval authority for the work accomplished. (DOD 4120.3-M) DISA CFS
agent A kind of intermediary service which acts on behalf of another service (service provider or requester) according to rules established upon its invocation. Also known as an "intelligent agent." OpenGIS Guide
agglomeration A generalization process that groups two or more proximate features to form a single feature. HDBK-850
aggregate domain Combinations of more primitive objects into aggregations. NOTE - Collections all combinations of more primitive objects into aggregations. Thus, they also define mechanisms for creating domains from existing domains. For example, elements from two numeric domains (or one repeated one) can be combined into ordered pairs (2-tuple) forming another domain. ISO/TC 211
Aggregate Level Simulation Protocol (ALSP) A family of simulation interface protocols and supporting infrastructure software that permit the integration of distinct simulations and war games. Combined, the interface protocols and software enable large-scale, distributed simulations and war games of different domains to interact at the combat object and event level. The most widely known example of an ALSP confederation is the Joint/Service Training Confederation (CBS, AWSIM, JECEWSI, RESA, MTWS, TACSIM, CSSTSS) that has provided the backbone to many large, distributed, simulation-supported exercises. Other examples of ALSP confederations include confederations of analytical models that have been formed to support U.S. Air Force, U.S. Army, and U.S. TRANSCOM studies. (DoD 5000.59-P, "Modeling and Simulation Master Plan," October 1995, authorized by DoD Directive 5000.59, January 4, 1994) JTA 2.0
Aggregate Segment {DII COE} A collection of segments grouped together, installed, deleted, and managed as a single unit. Aggregates are a convenient way for grouping segments that need to be developed and managed separately, but which must be presented to an operator as a single collection of functions. DII COE IRTS
aggregated attribute A collection of attributes. CEN/TC 287
aggregation The combining of data collected at point locations or smaller statistical units into larger units. HDBK-850
aggregation mode A generalization process that performs any of the following: (1) groups two or more points to form a single point; (2) groups two or more points to form a single line; (3) groups two or more points to form a single area; (4) groups two or more lines to form a single line; (5) groups two or more lines to form a single area. USIS 95
aggregation operations The process of bringing together many distinct parts or categories of data into one grouping, usually as a composite display. HDBK-850
aggregation relationship Subtype of feature relationship describing a complex object as a composition of other features. ISO/TC 211
agonic line (JCS) A line drawn on a map or chart joining points of zero magnetic declination for a specified year date. In nautical and aeronautical navigation, the term magnetic variation is used instead of magnetic declination. HDBK-850
aiming line See line of sight, definition 2; line of collimation. HDBK-850
Aimpoint Graphic Reference cards built for aircrew use that contain reference data for radar fix points, including imagery of the fix points. USIS 95
Air Almanac A joint publication of the United States Naval Observatory and Her Majesty's Nautical Almanac Office. It covers a 6-month period. It contains tabulated values of the Greenwich hour angle and declination of selected celestial bodies, plus additional celestial data used in navigation. HDBK-850
air base 1. (photogrammetry) The line joining two air stations, or the length of that line. 2. The distance, at the scale of the stereoscopic model, between adjacent perspective centers as reconstructed in the plotting instrument. See also air station. HDBK-850
Air Combat Command (ACC) The mission of the ACC is to provide air combat forces to America's Unified Combatant Commands. ACC operates fighter, bomber, reconnaissance, battle-management, rescue and theater airlift aircraft, as well as command, control, communications and intelligence systems. ACC is headquartered at Langley AFB, VA. ACC Web Site
air coordinates See rectangular space coordinates. HDBK-850
air defense identification zone Airspace of defined dimensions within which the ready identification, location, and control of airborne vehicles are required. USIS 95
Air Education and Training Command (AETC) The AETC recruits, accesses, commissions, trains and educates Air Force enlisted and officer personnel; provides basicmilitary training, initial and advanced operations training, flying training, and professional military and degree-granting professional education; and conducts joint, medical service, readiness and Air Force security assistance training. The AETC is headquartered at Randolph AFB, TX. AETC Web Site
Air Facilities Graphic Successor to the Air and Seaplane Stations of the World (ASSOTW). USIS 95
Air Force Agency for Modeling and Simulation (AFAMS) The AFAMS's mission is to support implementation and use of the Joint Synthetic Battlespace by: implementing AF/DoD M&S policy and standards; managing, coordinating, and integrating major AF M&S programs and initiatives; supporting corporate Air Force M&S operations; and promoting and supporting technology improvements. The AFAMS is located in Orlando, FL. AFAMS Web Site
Air Force Communications Agency (AFCA) AFCA's mission is to help the Air Force maintain information superiority by ensuring communications and information systems used by the warfighter are integrated and interoperable. The agency develops technical standards, visionary architectures, and imaginative solutions that meet customer needs and expectations. The AFCA is located at Scott AFB, IL. AFCA Web Site
Air Force Global Weather Central (AFGWC) The AFGWC was realigned into the Air Force Weather Agency (AFWA) on October 15, 1997. AFWA Web Site
Air Force Information Warfare Center (AFIWC) The AFIWC was activated on Sept. 10, 1993. Formerly the Air Force Electronic Warfare Center (AFEWC), AFIWC was established by combining the securities functions of the Air Force Cryptologic Support Center with the functions performed by AFEWC. The center is the focal point for development and application of information dominance in future warfare. It provides commanders with products and services to wage command and control warfare. The center is charged with protecting friendly command and control capability including United States Air Force (USAF) computer security. It is the primary source of electronic warfare and command, control and communications countermeasure analysis and advice for the Air Force. It also maintains a massive data base of electronic combat-related information that is used throughout the Department of Defense. The data assists air component commanders in making electronic combat decisions. AFIWC performs analyses to support planning, developing and testing using the latest electronic warfare equipment. The center also supports the electronic combat acquisition process, from development of statements of need through final testing by providing specialized analysis to Air Force major commands and the Air Staff. USAF Web Site
Air Force Materiel Command (AFMC) Through integrated management of research, development, test acquisition, and support, AFMC advances and uses technology to acquire and sustain superior systems in partnership with its customers and suppliers. AFMC performs continuous product and process improvement throughout the life cycle. As an integral part of the Air Force War Fighting Team, AFMC contributes to affordable combat superiority, readiness, and sustainability. AFMC is headquartered at Wright-Patterson AFB, OH. AFMC Web Site
Air Force Mission Support System A program to broaden automated support to mission planning and execution; mission planning systems are to connect with C3I at unit, wing, and theater levels. USIS 95
Air Force Research Laboratory (AFRL) The mission of the AFRL is to lead the discovery, development, and transition of affordable, integrated technologies for U.S. air and space forces. The AFRL is headquartered at Wright-Patterson AFB, OH. AFRL Web Site
Air Force satellite communications System provides UHF channeled, low-data-rate service primarily to support strategic and theater nuclear capabilities. System has no dedicated satellites, but rather uses relay packages and other systems. USIS 95
Air Force Space Command (AFSPC) The mission of the AFSPC is to defend the United States of America through the control and exploitation of space by making space exploitation reliable and routine for the warfighter by continuously improving the command's ability to provide and support combat forces. AFSPC is the Air Force component of the USSPACECOM. AFSPC is headquartered at Peterson AFB, CO. AFSPC Web site
Air Force Special Operations Command (AFSOC) AFSOC is the Air Force component of U.S. Special Operations Command (USSOCOM). The command is committed to continual improvement to provide Air Force special operations forces for worldwide deployment and assignment to regional unified commands to conduct: Unconventional warfare; Direct action; Special reconnaissance; Counter-proliferation; Foreign Internal Defense; Information Operations; Psychological operations; Civil Affairs; and Combating terrorism. AFSOC is headquartered at Hurlburt Field, FL. AFSOC Web Site
Air Force special operations detachment A squadron-size headquarters, that could be a composite organization of different Air Force special operations assets. The detachment is normally subordinate to an Air Force special operations component, joint special operations task force, or joint task force, depending upon size and duration of the operation. USIS 95
Air Force special operations element An element-size Air Force special operations headquarters. It is normally subordinate to an Air Force special operations command or detachment, depending on size and duration of the operation. USIS 95
Air Force special operations forces Those active and reserve component Air Force forces designated by the Secretary of Defense that are specifically organized, trained, and equipped to conduct and support special operations. USIS 95
Air Force Technical Applications Center (AFTAC) Located at Patrick AFB, Florida. Operates and maintains the U.S. Atomic Energy Detection System, a worldwide system of sensors that detect explosions underground, underwater, in the atmosphere, and in space. Determines if the explosions are nuclear in origin and reports them to national command authorities. AFTAC Web Site
Air Force Weather Agency (AFWA) On October 15, 1997, the Air Weather Service (AWS) Field Operating Agency (FOA) was redesignated as the Air Force Weather Agency (AFWA) FOA. This action realigned Headquarters AWS (HQ AWS), Scott AFB, IL, and the Air Force Global Weather Center (AFGWC), Offutt AFB, Neb., into a single headquarters with offices initially split between Offutt and Scott. Over the next two years, the Scott personnel authorizations and operational functions will move to Offutt. AFWA Web Site
Air Intelligence Agency (AIA) The AIA, headquartered at Kelly Air Force Base, Texas, is a field operating agency reporting directly to the Headquarters United States Air Force (USAF) assistant chief of staff for intelligence. AIA, activated on Oct. 1, 1993, is the Air Force's single source intelligence agency, combining various intelligence disciplines to provide current, accurate data to air component commanders and national decision makers. AIA provides multi-source intelligence products, applications, services and resources in the areas of information warfare/command and control warfare (IW/C2W), security, acquisition, foreign weapons systems and technology, and treaty monitoring. It is the executive agent for U.S. Air Force-wide intelligence roles and functions. USAF Web Site
air mission intelligence report A detailed report of the results of an air mission, including a complete intelligence account of the mission. USIS 95
Air Mobility Command (AMC) AMC's mission is to provide airlift, air refueling, special air mission, and aeromedical evacuation for U.S. forces. AMC also supplies forces to theater commands to support wartime tasking. As the Air Force component of the United States Transportation Command (USTRANSCOM), AMC is the single manager for air mobility. AMC is headquartered at Scott AFB, IL. AMC Web Site
Air National Guard (ANG) The ANG is administered by the National Guard Bureau, a joint bureau of the departments of the United States Army (USA) and United States Air Force (USAF), located in the Pentagon, Washington, D.C. The ANG's state and federal mission is to provide trained, well-equipped men and women who can augment the active force during national emergencies or war, and provide assistance during natural disasters and civil disturbances. When Guard units are in a non-mobilized status they are commanded by the governor of their respective state, Puerto Rico, Guam, Virgin Islands and the commanding general of the District of Columbia National Guard. The governors (except in the District of Columbia) are represented in the chain of command by the adjutant general of the state or territory. USAF Web Site
air observer An individual whose primary mission is to observe or take photographs from an aircraft in order to adjust artillery fire or obtain military information. USIS 95
air order of battle A listing of air facilities with aircraft counts and status. USIS 95
air photograph See aerial photograph. HDBK-850
air plot (JCS) 1. A continuous plot used in air navigation of a graphic representation of true headings steered and air distances flown. 2. A continuous plot of the position of an airborne object represented graphically to show true headings steered and air distances flown. 3. Within ships, a display which shows the positions and movements of an airborne object relative to the plotting ship. HDBK-850
air station (JCS) In photogrammetry, the point in space occupied by the camera lens at the moment of exposure. Also called camera station. See also air base. HDBK-850
air surveillance 1. The systematic observation of air space by electronic, visual, or other means, primarily for the purpose of identifying and determining the movements of aircraft and missiles, in the air space under observation. 2. Any reconnaissance conducted by satellites, aircraft, balloons, drones, remote-piloted vehicles (RPVs), or other airborne platforms. USIS 95
air surveillance plotting board (JCS) A gridded, small scale, air defense map of an appropriate area. It is maintained at the air control center. On it are posted current locations, number, and altitudes of all friendly or enemy aircraft within range of radar or ground observer facilities. HDBK-850
Air Target Chart (ATC) (JCS) A display of pertinent air target intelligence on a specialized graphic base. It is designed primarily to support operations against designated air targets by various weapon systems. The charts provide graphic overprint and textual data relative to radar return information and installations within the area. Air Target Charts are prepared at various scales and are produced under the Air Target Materials Program (ATMP) as a series of geographically integrated charts. There are 25 ATCs in a World Aeronautical Chart (WAC) each covering an area 72 nautical miles by 48 nautical miles. HDBK-850
air target materials See target materials. HDBK-850
Air Target Materials Program (ATMP) (JCS) A DoD program under the management control of the [National Imagery and Mapping Agency (NIMA)] established for and limited to the production of medium- and large-scale map, chart, and geodetic products which support worldwide targeting requirements of the unified and specified commands, the military departments, and allied participants. It encompasses the determination of production and coverage requirements, standardization of products, establishments of production priorities and schedules, and the production, distribution, storage, and release/exchange of products included under it. JPUB 1-02
air target mosaic A large-scale mosaic providing photographic coverage of an area and permitting comprehensive portrayal of pertinent target detail. These mosaics are used for intelligence study and in planning and briefing for air operations. JPUB 1-02
air tasking order (ATO) A method used to task and disseminate to components, subordinate units, and command and control agencies projected sorties/capabilities/forces to targets and specific missions. Normally provides specific instructions to include call signs, targets, controlling agencies, etc., as well as general instructions. JPUB 1-02
Air Weather Service (AWS) The AWS was redesignated as the Air Force Weather Angency (AFWA) on October 15, 1997. AFWA Web Site
airborne collection operations Airborne collection operations encompasses the capabilities required to translate collection tasks into the airborne collector geometries and sensing tasks required to accomplish collection task specifications, and collect imagery data. USIS 95
Airborne Control (ABC) system A survey system for horizontal and vertical control surveys involving electromagnetic distance measurements and horizontal and vertical angle measurements from two or more known positions to a helicopter hovering over the unknown position. The elevation of the unknown position is determined by the use of a special plumb line cable. HDBK-850
Airborne Data Link Program A program to link theater aircraft imagery to multiusers at multiple locations. USIS 95
airborne electronic survey control Control surveys accomplished by electronic means from an airborne vehicle or platform, such as hiran and shoran. HDBK-850
airborne landing model A specially designed assault model for use in briefing airborne troops and support personnel. These models emphasize the aspects of objects as seen from the air rather than from the ground. HDBK-850
Airborne Profile Recorder (APR) See Terrain Profile Recorder (TPR). HDBK-850
airborne reconnaissance low A low profile COMINT and IMINT collector of sensitive theater-organic targets. Uses the DHC-7 (DASH-7) aircraft. USIS 95
Airborne Visible/InfraRed Imaging Spectrometer (AVIRIS) An imaging spectrometer developed by NASA that has 224 spectral channels ranging from .4 to 2.45 microns. USIS 95
Airborne Warning and Control System Airborne system to aid fighter operations. USIS 95
Aircraft Mission Rehearsal System (ARMS) Software which allows the user full control over the flight path. AMRS provides the user the capability to "fly through" a bounded area using imagery draped over DTED data. This capability permits route rehearsals or reviews of unfamiliar territory prior to operations. USIS 95
Aircraft Summary Cable An electronic reporting product that disseminates one or more target or topic reports that address the imagery exploitation results of nationally tasked aircraft missions. USIS 95
airway (JCS) A control area or portion thereof established in the form of a corridor marked with radio navigational aids. HDBK-850
Airy spheroid (ellipsoid) A reference ellipsoid used in Great Britain and having the following dimensions: semimajor axis-6,377,563.396 meters; semiminor axis-6,356,256.910 meters; and the flattening or ellipticity-1/299.3249646. HDBK-850
Airy theory of isostasy The theory that the continents and islands are resting hydrostatically on highly plastic or liquid material, with roots or projections penetrating the inner material of the Earth, just as icebergs extend downward into the water. The greater the elevation, the deeper the penetration. It has been called the roots of mountain theory, and has the support of some geologists. See also Pratt-Hayford theory of isostasy. HDBK-850
Aitoff equal-area map projection A Lambert equal-area azimuthal projection of a hemisphere converted into a map projection of the entire sphere by a manipulation suggested by Aitoff. Lt is a projection bounded by an ellipse in which the line representing the Equator (major axis) is double the length of the line representing the central meridian (minor axis). HDBK-850
albedo The ratio of radiant energy reflected to that received by a surface, usually expressed as a percentage; reflectivity. The term generally refers to energy within a specific frequency range, as the visible spectrum. Its most frequent application is to the light reflected by a celestial body. HDBK-850
Albers conical equal-area map projection An equal-area projection of the conical type, on which the meridians are straight lines that meet in a common point beyond the limits of the map, and the parallels are concentric circles whose center is at the point of intersection of the meridians. Meridians and parallels intersect at right angles and the arcs of longitude along any given parallel are of equal length. The parallels are spaced to retain the condition of equal area. On two selected parallels, the arcs of longitude are represented in their true length. Between the selected parallels the scale along the meridians will be a trifle too large, and beyond them, too small. HDBK-850
albumin (albumen) process A process of making photolithographic press plates utilizing bichromated albumin as the photosensitive coating, and requiring a true negative to make the printing plate. See also plate. HDBK-850
Aldis signaling lamp A signaling lamp used in some cases for night observations of distant stations in triangulation. HDBK-850
alerts An ephemeris prepared for one or more satellites, predicting rise and set times referred to universal time coordinated, maximum angle of elevation above the observer's horizon, and azimuth from the observer. Used to identify specific satellite passes. See also look angles. HDBK-850
alidade The part of a surveying instrument which consists of a sighting device, with index, and reading or recording accessories. See also peepsight alidade; pendulum alidade; photoalidade; telescopic alidade. HDBK-850
alignment (alinement) 1. (cartography) Representation of a road, railway, etc., on a map or chart in relation to surrounding topographic detail. 2. (general surveying) The placement or location of points along a straight line. 3. (highway and route surveying) The ground plan showing the direction (center line) of the route to be followed, as distinguished from profile, which shows the vertical element. HDBK-850
alignment correction (taping) A correction applied to the measured length of a line to allow for the tape not being held exactly in a vertical plane containing the line. HDBK-850
All-Source Analysis System (ASAS) The Army's all-purpose battlefield information system. Primary functions include collection management; signals intelligence analysis, to include COMINT and ELINT integration; all-source processing; message processing; situation development; target development, electronic warfare support; and operations security support. USIS 95
All-Source Analysis System (ASAS) - Warrior This system, in part, is the focal point for exchange of intelligence information with other services, allies, theater and national intelligence sources. USIS 95
all-source intelligence Intelligence produced using all available sources and agencies. USIS 95
almanac A periodical publication of astronomic coordinates useful to a navigator. It contains less information than an ephemeris and values are generally given to less precision. See also ephemeris. HDBK-850
ALMAZ A Russian satellite-borne radar system. ALMAZ has been declassified and made available for civil use. ALMAZ provides 15- to 30-meter resolution. USIS 95
almucantar See parallel of altitude. HDBK-850
along-trace (A/T) The direction of the tangent to a locus of points on the earth, a constant distance from the satellite ground path. Positive in the direction of satellite motion. HDBK-850
along-track Dimension parallel to the path of the platform carrying the sensor. The 'along track' dimension is the imaging direction of the sensor that is parallel to the direction in which the satellite or aircraft is moving.This term refers to both optical and radar systems. For side-looking radars, this dimension is sometimes called the cross range or azimuth direction. The typical two-dimensional remotely sensed image is created by the movement of the platform in the 'along track' direction, while the sensor scans or aims at the orthogonal direction. CCRS Glossary
Along-track Scanning Radiometer (ATSR) The ATSR was designed to provide the following types of data and observations: (1) sea surface temperature with an absolute accuracy of better than 0.5 K with a spatial resolution of 50 km and in conditions of up to 80% cloud cover; (2) images of surface temperature with 1 km resolution and 500 km swath, relative accuracy around 0.1 K; and (3) measurement of the atmospheric integrated water content (vapour and liquid) in order to compute the most problematic path delay in the signal of the Radar Altimeter. The ATSR consists of two instruments, an Infra-Red Radiometer (IRR) and a Microwave Sounder (MWS). ATSR-1 is on-board the European Space Agency's (ESA) Remote Sensing Satellite 1 (ERS-1). ATSR-2, an improved version of ATSR-1, is on-board ERS-2. ESA Web Site
alphanumeric grid See atlas grid. HDBK-850
altazimuth instrument An instrument equipped with both horizontal and vertical graduated circles, for the simultaneous observation of horizontal and vertical directions or angles. Also called astronomic theodolite; universal instrument. HDBK-850
alternate routing An alternate communications path used if the normal one is not available. One or more possible alternate paths are possible. [Joint Pub 6-02.1] DISA CFS
altimeter An instrument that indicates the height above a reference surface. See also barometric altimeter; precision altimeter; radar altimeter; surveying altimeter. HDBK-850
altimetry The art and science of measuring altitudes by barometric means and interpreting the results. HDBK-850
altitude 1. The vertical distance of a point, or an object considered as a point, measured from a reference surface, as mean sea level (the geoid), ellipsoid, mean terrain. 2. Angular distance above the horizon; the arc of a vertical circle between the horizon and a point on the celestial sphere, measured upward from the horizon. See also absolute altitude; angular altitude; apparent altitude; circummeridian altitudes; computed altitude; density altitude; elevation; ellipsoidal height; exmeridian altitude; flight altitude; geoidal height; high altitude; meridian altitude; negative altitude; observed altitude; orbital altitude; parallel of altitude; photo altitude; positive altitude; pressure altitude; radar altitude; sextant altitude; simultaneous altitudes; solar altitude; true altitude. HDBK-850
altitude circle See parallel of altitude. HDBK-850
altitude contour ratio See C-factor. HDBK-850
altitude datum (JCS) The arbitrary level from which vertical displacement is measured. The datum for height measurement is the terrain directly below the aircraft or some specified datum; for pressure altitude, the level at which the atmospheric pressure is 29.92 inches of mercury (1013.2 mbs); and for true altitude, mean sea level. HDBK-850
altitude difference The difference between computed and observed altitudes, or between precomputed and sextant altitudes. Also called altitude intercept. HDBK-850
altitude hole (JCS) The blank area at the origin of a radial display, on a radar tube presentation, the center of the periphery of which represents the point on the ground immediately below the aircraft. In side-looking airborne radar, this is known as the altitude slot. HDBK-850
altitude intercept See altitude difference. HDBK-850
altitude slot See altitude hole. HDBK-850
altitude tints See hypsometric tinting. HDBK-850
American Congress on Surveying and Mapping (ACSM) A non-profit educational organization, ACSM's objectivs are to advance the sciences of surveying and mapping and related fields, in furtherance of the welfare of those who use and make maps; to encourage the development of educational programs in surveying, mapping and charting; and to support publications that represent the professional and technical interests of surveying and mapping. The ACSM is headquartered in Bethesda, MD. ACSM Web Site
American Forces Information Service (AFIS) AFIS, under the authority, direction, and control of the Assistant to the Secretary of Defense (Public Affairs) (DoD Directive 5122.10): (1) advises and acts for the ASD(PA) in managing DoD internal information programs; (2) develops policies, guidelines, and standards for the management of DoD visual information (VI) activities and programs; (3) develops policies, guidelines, and standards for the management of Armed Forces Radio and Television Service (AFRTS) outlets and activities; and (4) provides joint-interest print, radio, film, and television materials for use in the internal information programs of the Military Departments and other DoD organizations. DefenseLINK
American National Standards Institute (ANSI) Serves as administrator and coordinator of the United States private sector voluntary standardization system. Founded in 1918 by five engineering societies and three government agencies, the Institute remains a private, nonprofit membership organization supported by a diverse constituency of private and public sector organizations. ANSI facilitates the development of American National Standards by establishing consensus among qualified groups. Its headquarters is in New York City, and its satellite office is in Washington, D.C. ANSI Web Site
American Society for Photogrammetry and Remote Sensing (ASPRS) The mission of the ASPRS is to advance knowledge and improve understanding of mapping sciences to promote the responsible application of photogrammetry, remote sensing, geographic information systems and supporting technologies. The ASPRS is headquartered in Bethesda, MD. ASPRS Web Site
American Standard Code for Information Interchange (ASCII) A widely used ANSI standard code which uses seven bits to represent numbers, letters, and control characters. Since eight-bit codes are more common on computers than seven-bit codes, ASCII is commonly embedded in an eight-bit code. It is mainly used to transmit data between digital devices. HDBK-850
amphibious assault landing model See assault landing model. HDBK-850
amphibious objective area A geographical area, delineated in the initiating directive, for purposes of command and control within which is located the objective(s) to be secured by the amphibious task force. This area must be of sufficient size to ensure accomplishment of the amphibious task force's mission and must provide sufficient area for conducting necessary sea, air, and land operations. USIS 95
amphidromic point A no-tide or nodal point on a chart of cotidal lines from which the cotidal lines radiate. HDBK-850
amphidromic region An area surrounding an amphidromic point in which the cotidal lines radiate from the no-tide point and progress through all hours of the tidal cycle. HDBK-850
amplitude 1. The maximum value of the displacement of a wave or other periodic phenomenon from a reference position. 2. Angular distance north or south of the prime vertical; the arc of the horizon or the angle at the zenith between the prime vertical and a vertical circle, measured north or south from the prime vertical to the vertical circle. The term is customarily used only with reference to bodies whose centers are on the celestial horizon, and is prefixed "E" or "W," as the body is rising or setting, respectively, and suffixed "N" or "S" to agree with the declination. See also compass amplitude; grid amplitude; magnetic amplitude; true amplitude. HDBK-850
amplitude of vibration (pendulum) The length of the arc passed over by a pendulum in moving from its mean position to the position of maximum displacement. HDBK-850
anaglyph A stereogram in which the two views are printed or projected superimposed in complementary colors, usually red and blue. By viewing through filter spectacles of corresponding complementary colors, a stereoscopic image is formed. HDBK-850
analemma 1. A figure eight shaped diagram drawn across the Torrid Zone on a terrestrial globe to show the declination of the Sun throughout the year and also the equation of time. 2. A sundial. HDBK-850
analog Pertaining to data in the form of continuously variable physical quantities. Contrast with: digital. [ IEEE610.1] IEEE 610-1990
analog gateway A means of connecting dissimilar codecs. Incoming digital signal from one type of codec is decoded by a similar codec and converted to analog. The analog signal is then passed to the dissimilar codec, coded, and decoded at the far end. Analog gateways achieve interoperability in a non-standard environment, but have the disadvantages of degrading video and audio quality and often reducing functionality. Multimedia
analog instruments Devices that represent numerical quantities by means of physical variables, giving all values within a particular range, for example, by translation; by rotation, as in a mechanical gear system; and by voltage or current as in analog networks that use resistance to represent mechanical losses,capacitors and inductors to store energy and simulate the action of springs, etc. HDBK-850
analysis A process in the production step of the Intelligence cycle in which intelligence information is subject to systematic examination in order to identify significant facts and derive conclusions therefrom. USIS 95
analytical aerotriangulation A photo-triangulation procedure (using aerial photography) in which the spatial solution is obtained by computational routines. HDBK-850
analytical nadir-point triangulation Radial triangulation performed by computational routines in which nadir points are utilized as radial centers. HDBK-850
analytical orientation Those computational steps required to determine tilt, direction of principal line, flight height, preparation of control templets at rectification scale, angular elements, and linear elements in preparing aerial photographs for rectification. Developed data are converted to values to be set on circles and scales of rectifier or transforming printer. HDBK-850
Analytical Photogrammetric Positioning System (APPS) A stereo photogrammetric work station used in conjunction with a Point Positioning Data Base (PPDB) for precise point positioning. See also Point Positioning Data Base (PPDB). HDBK-850
analytical photogrammetry Photogrammetry in which solutions are obtained by mathematical methods. HDBK-850
analytical photography Photography, either motion picture or still, accomplished to determine (by qualitative, quantitative, or any other means) whether a particular phenomenon does or does not occur. HDBK-850
analytical radar prediction Prediction based on proven formulas, power tables, graphs, and/or other scientific principles. An analytical prediction considers surface height, structural and/or terrain information and criteria for radar reflectivity together with the aspect angle and range to the target. HDBK-850
analytical radial triangulation Radial triangulation performed by computational routines. See also graphical radial triangulation. HDBK-850
analytical three-point resection radial triangulation A method of computing the coordinates of the principal points of overlapping aerial photographs by resecting on three horizontal control points appearing in the overlap area. HDBK-850
anastigmatic lens A lens which has been corrected for astigmatism and, therefore, focuses vertical and horizontal lines with equal brightness and definition. Anastigmatic lenses are also free of most common aberrations. HDBK-850
anchorage chart A nautical chart showing prescribed or recommended anchorages. HDBK-850
aneroid altimeter See barometric altimeter. HDBK-850
aneroid barometer A barometer which balances the atmospheric pressure against a mechanically elastic device. The usual form of an aneroid barometer consists of a thin box of corrugated metal, almost exhausted of air. When the atmospheric pressure increases, the box contracts; when the pressure lessens, the box expands. By mechanical means these movements are amplified and communicated to an index hand which registers the changes on a graduated dial. HDBK-850
angle The inclination to each other of two intersecting lines, measured by the arc of a circle intercepted between the two lines forming the angle, the center of the circle being the point of intersection. See also adjusted angle; altitude; azimuth; azimuth angle; break angle; conversion angle; counterclockwise angle; concluded angle; crab angle; critical angle; crossing angle; deflection angle; dihedral angle; dip angle; direct angle; direction angle; distance angle; double zenith distance; drift angle; Eulerian angles; Greenwich hour angle; grid magnetic angle; horizontal angle; hour angle; interlocking angle; local hour angle; locking angle; look angles; measured angle; meridian angle; oblique ascension; observed angle; parallactic angle; phase angle; reciprocal vertical angle; refraction angle; repetition of angles; right ascension; screen angle; sidereal hour angle; slope angle; solid angle; spherical angle; spheroidal angle; traverse angle; vectorial angle; vertical angle; zenith distance. HDBK-850
angle equation A condition equation which expresses the relationship between the sum of the measured angles of a closed figure and the theoretical value of that sum, the unknowns being the corrections to the observed directions or angles, depending on which are used in the adjustment. HDBK-850
angle method of adjustment (triangulation and traverse) A method of adjustment of observations which determines correction to observed angles. The angle method of adjustment may be used where a chain of single triangles is to be adjusted. HDBK-850
angle of convergence (JCS) The angle subtended by the eyebase of an observer at the point of focus. Also called angular parallax; parallactic angle. HDBK-850
angle of coverage See angle of field. HDBK-850
angle of current (hydrography) In stream gaging, the angle of current is the angular difference between 90 and the angle made by the current with a measuring section. HDBK-850
angle of depression (JCS) 1. The angle in a vertical plane between the horizontal and a descending line [as from an observer to an object]. 2. In air photography, the angle between the optical axis of an obliquely mounted air camera and the horizontal. Also called depression angle; descending vertical angle; minus angle. See also angle of elevation; tilt angle; true depression angle. HDBK-850
angle of deviation (optics) The angle through which a ray is bent by refraction. HDBK-850
angle of elevation The angle in a vertical plane between the horizontal and an ascending line, as from an observer to an object. Also called ascending vertical angle; plus angle. See also angle of depression. HDBK-850
angle of field A property of a lens. The angle subtended by lines that pass through the center of the lens and locate the diameter of the maximum image area within the specified definition of the lens. Lenses are generally classified according to their angles of coverage, as follows: narrow-angle; wide-angle; normal-angle; and superwide-angle or ultrawide-angle. Also called angle of coverage; angular field. HDBK-850
angle of incidence (optics) As measured from the normal, the angle at which a ray of light strikes a surface. HDBK-850
angle of inclination An angle of elevation or angle of depression. HDBK-850
angle of reflection (optics) As measured from the normal, the angle at which a reflected ray of light leaves a surface. HDBK-850
angle of refraction The angle which the refracted ray makes with the normal to the surface separating two transparent media. HDBK-850
angle of tilt See tilt. HDBK-850
angle of view (JCS) 1. The angle between two rays passing through the perspective center (rear nodal point) of a camera lens to two opposite corners of the format. 2. In photogrammetry, twice the angle whose tangent is one-half the length of the diagonal of the format divided by the calibrated focal length. Also called covering power; field of view. HDBK-850
angle of yaw The angle between a line in the direction of flight and a plane through the longitudinal and vertical axes of an aircraft. It is considered positive if the nose is displaced to the right. Also called yaw angle. HDBK-850
angle point A term applied to a marker at each point to indicate a change in the direction of a survey line. HDBK-850
angle to right The horizontal angle measured clockwise from the preceding line to the following one. Also called clockwise angle. HDBK-850
angle-to-right traverse In surveying, a technique applicable to either open or closed traverses, wherein all angles are measured in a clockwise direction after the transit has been oriented by a backsight to the preceding station. HDBK-850
angstrom A unit of measurement of wavelength of light and other radiation. Equal to one ten-thousandth of a micron or one hundred-millionth of a centimeter. The visible spectrum extends from about 4,000 to 8,000 angstroms. USIS 95
angular altitude A measure in degrees of a given object above the horizon, taken from a given or assumed point of observation, and expressed by the angle between the horizontal and the observer's line of sight. HDBK-850
angular calibration constants In a multiple-lens camera, or multiple-camera assembly, the values of angular orientation of the lens axes of the several lens-camera units to a common reference line. For example, in a trimetrogon camera, the angular relationships of the wing camera axis with respect to the axis of the central (vertical) camera. HDBK-850
angular distance 1. The angular difference between two directions, numerically equal to the angle between two lines extending in the given directions. 2. The arc of the great circle joining two points, expressed in angular units. 3. Distance between two points, expressed in angular units of a specified frequency. It is equal to the number of waves between the points multiplied by 2p if expressed in radians, or multiplied by 360 if expressed in degrees. HDBK-850
angular distortion 1. (cartography) Distortion in a map projection because of nonconformality. 2. (optics) The failure of a lens to reproduce accurately in the image space the angle subtended by two points in the object space. HDBK-850
angular error of closure See error of closure, definition 2. HDBK-850
angular field See angle of field. HDBK-850
angular magnification The ratio of the angle subtended at the eye by the image formed by an optical device, to the angle subtended at the eye by the object itself without the optical device. This is convenient where a distance in the object cannot be measured for expressing a linear magnification, as in using a telescope. HDBK-850
angular momentum The quantity obtained by multiplying the moment of inertia of a body by its angular speed. HDBK-850
angular parallax See angle of convergence. HDBK-850
angular rate See angular speed. HDBK-850
angular speed Change of direction per unit time. Also called angular rate. HDBK-850
angular velocity A representation of the rate of rotation of a particle about the axis of rotation, with magnitude equal to the time rate of angular displacement of any point of the body. HDBK-850
angulator An instrument for converting angles measured on an oblique plane to their corresponding projections on a horizontal plane. A rectoblique plotter and photoangulator are types of angulators. See also equiangulator; topoangulator. HDBK-850
annex point A point used to assist in the relative orientation of vertical and oblique photographs, selected in the overlap area between the vertical and its corresponding oblique about midway between the pass points. Alternate sets of photographs only will contain annex points. See also pass point. HDBK-850
annotated image A hardcopy or softcopy image with notes, labels, and/or symbols added to describe, explain, or identify items of significance. USIS 95
Annotated Image Graphic An image annotated with exploitation results (e.g., target materials, basic reference graphics briefing boards/transparencies, etc.). USIS 95
annotated photograph A photograph on which hypsographic, geologic, cultural, hydrographic, vegetation, or place name information has been added to identify, classify, outline, clarify, or describe features that would not otherwise be apparent in examination of an unmarked photograph. Generally, the term does not apply to photographs marked only with geodetic control or pass points. HDBK-850
annotation (JCS) A marking placed on imagery or drawings for explanatory purposes or to indicate items or areas of special importance. HDBK-850
annotation overprint The outline delimiting a target or installation, or a symbol which locates its position together with an identifying reference number as depicted on a target graphic. HDBK-850
annotation text A descriptive text containing the identification, function, location, physical characteristics, and other information concerning a target or installation. Descriptive texts are also prepared for special areas, radar significant power lines, and precise radar significant location points. HDBK-850
annual aberration Aberration caused by the velocity of the Earth's revolution about the Sun. HDBK-850
annual change See magnetic annual change. HDBK-850
annual inequality Seasonal variation in water level or tidal current speed, more or less periodic, due chiefly to meteorological causes. HDBK-850
annual magnetic change See magnetic annual change. HDBK-850
annual magnetic variation See magnetic annual variation. HDBK-850
annual parallax The angle subtended at a celestial body by the radius of the Earth's orbit. Also called heliocentric parallax; stellar parallax. HDBK-850
annual rate See magnetic annual change. HDBK-850
annual rate of change See magnetic annual change. HDBK-850
annular eclipse An eclipse in which a thin ring of the source of light appears around the obscuring body. Annular solar eclipses occur, but never annular lunar eclipses. HDBK-850
anomalistic drift The variation or drift of a frequency source. For example, the frequency changes of a crystal oscillator due to a variety of causes, such as temperature variation and component aging, none of which can be predicted in advance or completely controlled. HDBK-850
anomalistic month The interval of time between two successive passages of the Moon in her orbit through perigee. The length of the anomalistic month is 27.55455 mean solar days. HDBK-850
anomalistic period The interval between two successive perigee passes of a satellite in orbit about its primary. Also called perigee-to-perigee period. HDBK-850
anomalistic tide cycle The average period of about 27 1/2 days, measured from perigee to perigee, during which the Moon completes one revolution around the Earth. HDBK-850
anomalistic year The period of one revolution of the Earth around the Sun, from perihelion to perihelion, 365 days, 6 hours, 13 minutes, 53.16 seconds in 1955, and increasing at the rate of 0.002627 second annually. HDBK-850
anomalous magnetic variation See local magnetic anomaly. HDBK-850
anomaly 1. (general) A deviation from the norm. 2. (geodesy) A deviation of an observed value from a theoretical value due to a corresponding irregularity in the Earth's structure at the area of observation. 3. (astronomy) The angle between the radius vector to an orbiting body from its primary and the line of apsides of the orbit, measured in the direction of travel, from the point of closest approach to the primary. This term is also called the true anomaly when it is desired to distinguish it from the eccentric anomaly, which is the corresponding angle at the center of the orbit; or from the mean anomaly, which is what the true anomaly would become if the planet had a uniformly angular motion. See also Bouguer anomaly; deflection anomaly; free-air anomaly; gravity anomaly; Hayford gravity anomalies; height anomaly; isostatic anomaly; local magnetic anomaly; magnetic disturbance; mean free-air anomaly; point anomaly; surface anomalies. HDBK-850
Antarctic Circle The geographic parallel having a south latitude equal to the complement of the declination of the winter solstice. The obliquity of the ecliptic is steadily changing so that the winter solstice is not a point of fixed declination, and the Antarctic Circle, as defined, is not a line of fixed position. When the Antarctic Circle is to be shown on a map, however, it is desirable that it be treated as a line of fixed position, and that a conventional value be adopted for its latitude. For this purpose, the value 6633' south latitude is used. Also called south polar circle. HDBK-850
antihalation coating (photography) A light-absorbing coating applied to the backside of the support of a film or plate (or between the emulsion and the support) to suppress halation. HDBK-850
antipode Anything exactly opposite to something else. Particularly, that point on the Earth 180 from a given place. HDBK-850
antisolar point That point on the celestial sphere 180 from the Sun. HDBK-850
Antisubmarine Warfare (ASW) Prediction Area Chart A standard NIMA hydrographic chart overprinted with homogeneous acoustic provinces characterized by a single velocity profile, a bottom loss class, and a bathymetric relief. HDBK-850
antivignetting filter (JCS) A filter bearing a deposit which is graduated in density to correct for the uneven illumination given by certain lenses, particularly wide-angle types. HDBK-850
apareon The point on a Mars-centered orbit where a satellite is at its greatest distance from Mars. HDBK-850
apastron That point of the orbit of one member of a double star system at which the stars are farthest apart. Opposite of periastron. HDBK-850
aperiodic compass Literally "a compass without a period," or a compass that, after being deflected, returns by one direct movement to its proper reading, without oscillation. Also called deadbeat compass. HDBK-850
aperture 1. The opening in a lens diaphragm through which light passes. 2. The diameter of the objective lens of a telescope or other optical instrument, usually expressed in inches, but sometimes as the angle between lines from the principal focus to opposite ends of a diameter of the objective lens. See also relative aperture. HDBK-850
aperture ratio See relative aperture. HDBK-850
aperture stop (optics) The physical element (such as a stop, diaphragm, or lens periphery) of an optical system which limits the size of the pencil of rays traversing the system. The adjustment of the size of the aperture stop of a given system regulates the brightness of the image without necessarily affecting the size of the area covered. Also called stop. HDBK-850
apex See vertex. HDBK-850
aphelion The point in the elliptical orbit of a planet which is the farthest from the Sun, when the Sun is the center of attraction. Opposite of perihelion. HDBK-850
aphylactic map projection A map projection which does not possess any of the three special properties of equivalence, conformality, or equidistance. Also called arbitrary projection. HDBK-850
aplanatic lens A lens which transmits light without spherical aberration. HDBK-850
aplune (apolune) The point on the elliptical orbit of a satellite of the Moon which is farthest from the Moon. Also called apocynthion. Opposite of perilune; pericynthion. HDBK-850
apoapsis See apocenter. HDBK-850
apocenter In an elliptical orbit, the point in the orbit which is the greatest distance from the focus where the attracting mass is located. Also called apoapsis; apofocus. Opposite of periapsis; pericenter; perifocus. HDBK-850
apochromatic lens A lens that has been corrected for chromatic aberration for three colors. HDBK-850
apocynthion See aplune (apolune). HDBK-850
apofocus See apocenter. HDBK-850
apogean tides Tides of decreased range occurring when the Moon is near apogee. HDBK-850
apogee (JCS) The point at which a missile trajectory or a satellite orbit is farthest from the center of the gravitational field of the controlling body or bodies. HDBK-850
aposphere A mathematical surface of constant curvature applicable to the earth spheroid over a certain limited area. It may be either oblate or prolate in shape. HDBK-850
apparent A term used to designate certain measured or measurable astronomic quantities to refer them to the observed position of celestial bodies. HDBK-850
apparent altitude The observed vertical angle of a celestial object corrected for instrumental errors, personal errors, and inaccuracies in the reference level (principally dip), but not for refraction, parallax, or semidiameter. Also called rectified altitude. HDBK-850
apparent horizon (JCS) The visible line of demarcation between land/sea and sky. Also called local horizon; topocentric horizon; visible horizon. HDBK-850
apparent motion Motion relative to a specified or implied reference point which may itself be in motion. The expression usually refers to movement of celestial bodies as observed from the Earth. Also called relative motion. HDBK-850
apparent noon Twelve o'clock apparent time, or the instant the apparent sun is over the upper branch of the meridian. HDBK-850
apparent place (astronomy) See apparent position. HDBK-850
apparent position An astronomic term applied to the observable position of a star, planet, or the Sun. The position on the celestial sphere at which a heavenly body (or a space vehicle) would be seen from the center of the Earth at a particular time. Also called apparent place. See also astrometric position. HDBK-850
apparent precession (JCS) The apparent deflection of the gyro axis, relative to the Earth, due to the rotating effect of the Earth and not due to any applied force. Also called apparent wander; wander. HDBK-850
apparent sidereal time The local hour angle of the true vernal equinox. Also called true sidereal time. HDBK-850
apparent solar day The interval of time from a transit of the apparent sun across a given meridian to its next successive transit across the same meridian. HDBK-850
apparent solar time Time measured by the apparent diurnal motion of the true sun. Also called apparent time; true solar time. HDBK-850
apparent sun The actual Sun as it appears in the sky. Also called true sun. HDBK-850
apparent time See apparent solar time. HDBK-850
apparent wander See apparent precession. HDBK-850
appearance ratio See hyperstereoscopy. HDBK-850
applet A small application, with limited functionality, designed to operate in a componentware and/or middleware environment. Large, multifunctional, "monolithic" applications can be, and in the future often will be, broken into single-function applets that interoperate with other applets, and that can be assembled, perhaps only temporarily, into a user's work environment. Java applets, for example, are typically downloaded via the Internet into your computer's program memory, where they accomplish their task (such as "let the user zoom on this geodata") and then "evaporate". OpenGIS Guide
application The use of capabilities provided by an information system specific to the satisfaction of a set of user requirements. Note: These capabilities include hardware, software, and data. IEEE P1003.0
Application Environment Profile (AEP) A profile, specifying a complete and coherent specification of the Open System Environment (OSE), in which the standards, options, and parameters chosen are necessary to support a class of applications. IEEE P1003.0
application layer Layer seven of the OSI Reference Model. It serves as a window through which applications access communication services. TAFIM 3.0
application model A term used to describe those functions of an organization that can be supported or automated through IT. It is used for grouping or clustering functions into applications. It provides the application developers' views of the IT architecture. TAFIM 3.0
application platform A set of resources, including hardware and software, that support the services on which application software will run. The application platform provides services at its interfaces that, as much as possible, make the specific characteristics of the platform transparent to the application software. IEEE P1003.0
application platform The collection of hardware and software components that provide the infrastructure services used by application programs. OpenGIS Guide
application portability The ability to move software among computers without rewriting it. This may be provided in three ways: as source code portability, pseudocode portability, or binary code portability. See User Portability. OpenGIS Guide
Application Portability Profile (APP) The structure that integrates Federal, national, international, and other specifications to provide the functionality necessary to accommodate the broad range of Federal information technology requirements. [APP] DISA CFS
application process The part of an application that resides in a single end system. TAFIM 3.0
Application Program Interface (API) The interface between the application software and the application platform, across which all services are provided. IEEE P1003.0
application schema The conceptual schema for a certain type of application. ISO/TC 211
application software Software that is specific to an application and is composed of programs, data, and documentation. IEEE P1003.0
application software entity Mission-area and support applications. A common set of support applications forms the basis for the development of mission-area applications. Mission-area applications should be designed and developed to access this set of common support applications. Applications access the Application Platform via a standard set of APIs. (TAFIM, Version 3.0, Volume 2) JTA 2.0
approach chart An aeronautical chart providing essential information for making an approach to an airfield under either visual or instrument flight conditions. HDBK-850
Approved Software {DII COE} Software that has been tested as compatible with the COE. An approved products list might contain Oracle, Sybase, WordPerfect, Kermit, etc. In this context, approved software implies only that the software has been tested and confirmed to work within the DII COE. It does not imply that the software has been approved or authorized by any government agency for any specific system. DII COE IRTS
approximate contour A contour substituted for a normal contour whenever there is a question as to its reliability (reliability is defined as being accurate within one-half the contour interval). HDBK-850
appulse The near approach of one celestial body to another on the celestial sphere, as in occultation or conjunction. HDBK-850
apse line See line of apsides. HDBK-850
apsidal cycle The period of time during which a satellite vehicle moves from perigee to apogee and back to perigee over a specified target. USIS 95
apsis Either of the two orbital points nearest or farthest from the center of attraction, the perihelion and aphelion in the case of an orbit about the Sun, and the perigee and apogee in the case of an orbit about the Earth. HDBK-850
arbitrary grid Any reference system developed for use where no grid is available or practical, or where military security for the reference is desired. HDBK-850
arbitrary projection See aphylactic map projection. HDBK-850
arc 1. (topology) An individual line segment defined by a series of X, Y coordinate pairs. Nodes are at the ends of arcs and form the points of intersection between arcs. 2. (geodesy) A portion of a geodetic triangulation network, between two high-order stations. 3. Acronym for Equal Arc Second Raster Chart/Map. HDBK-850
arc correction (pendulum) The quantity which is applied to the period of vibration of a pendulum to allow for the pendulum's departure from simple harmonic motion. HDBK-850
ARC Digitized Raster Graphics (ADRG) ARC (equal Arc second Raster Chart/map) Digitized Raster Graphics (ADRG) are digital raster representations of paper graphic products. Maps/charts are converted into digital data by raster scanning and transforming the map image into the ARC System frame of reference. Data collected from a single chart/map series and scale will be maintained as a worldwide seamless data base of raster graphic data with each pixel having a distinct geographic location.. See also ARC Projection System; Equal Arc Second Raster Chart/Map; Compressed ARC Digitized Raster Graphics (CADRG). NIMA LOP
arc measurement A survey method used to determine the size of the Earth. A long arc is measured on the Earth's surface and the angle which subtends this measured arc is determined. By assumptions and mathematical formula the size and shape of the Earth can then be determined. HDBK-850
arc navigation A navigation system in which the position of an airplane or ship is maintained along an arc measured from a control station by means of electronic distance measuring equipment, such as SHORAN. See also LORAN. HDBK-850
arc of parallel A part of an astronomic or geodetic parallel of latitude. HDBK-850
arc of visibility The horizontal angular range through which a navigation light is visible form seaward. The angular range is defined by limiting bearings of direction. HDBK-850
ARC Projection System A coordinate system that divides the world into 18 latitudinal zones. See also Equal Arc Second Raster Chart/Map (ARC); ARC Digitized Raster Graphics (ADRG). HDBK-850
arc triangulation A system of triangulation of limited width designed to progress in a single general direction. Arc triangulation is executed for the purpose of connecting independent and widely separated surveys, coordinating, and correlating local surveys along the arc, furnishing data for the determination of a geodetic datum, providing a network of control points for a countrywide survey, etc. HDBK-850
architectural component Component: One of the parts that make up a system. A component may be hardware or software and may be subdivided into other components. Note: The terms "module," "component," and "unit" are often used interchangeably or defined to be sub-elements of one another in different ways depending on the context. The relationship of these terms is not yet standardized. [IEEE 610.12] IEEE 610-1990
architectural framework Identifies key interfaces and services, and provides a context for identifying and resolving policy, management and strategic technical issues. Constrains implementation by focusing on interfaces, but does not dictate design or specific technical solutions. OpenGIS Guide
architectural reference model {TC 211} A part of the ISO/TC 211 Reference Model that identifies the general classes of geographic information services that will be provided by computer systems to manipulate geographic information and enumerates the critical interfaces for those services. ISO/TC 211
architectural structure Provides the conceptual foundation of the basic architectural design concepts, the layers of the technical architecture, the services provided at each layer, the relationships between the layers, and the rules for how the layers are interconnected. TAFIM 3.0
architecture The structure of components, their relationships, and the principles and guidelines governing their design and evolution over time. C4ISR AF
architecture Architecture has various meanings, depending upon its contextual usage. (1) The structure of components, their interrelationships, and the principles and guidelines governing their design and evolution over time. (2) Organizational structure of a system or component. [IEEE STD 610.12; TAFIM, Version 3.0, Volumes 1 and 3] -or- An architecture is a composition of (1) components (including humans) with their functionality defined (Technical), (2) requirements that have been configured to achieve a prescribed purpose or mission (Operational), and (3) their connectivity with the information flow defined (System). [OS-JTF] JTA 2.0
Architecture Database (TAP) A relational database containing data necessary for the production of C4ISR Architecture products. NIMA/AR
architecture description A representation, as of a current or future point in time, of a defined "domain" in terms of its component parts, what those parts do, how the parts relate to each other, and rules and constraints under which the parts function. C4ISR AF
architecture of a system A set of rules that define the structure of a system and inter-relationships between its parts. RM-ODP
architecture target Depicts the configuration of the target open information system. [DOD 8020.1-M] DISA CFS
architecture views See views, architecture. C4ISR AF
architecture, baseline and target Defined and are significant parts of the technical management planning information (previously the technical management plan [TMP]). [DOD 8020.1-M with Change 1]. DISA CFS
architecture, database The logical view of the data models, data standards, and data structure. It includes a definition of the physical databases for the information system, their performance requirements, and their geographical distribution. [DOD 8020.1-M, Appendix J] DISA CFS
architecture, infrastructure Identifies the top-level design of communications, processing, and operating system software. It describes the performance characteristics needed to meet database and application requirements. It provides a geographic distribution of components to locations. The infrastructure architecture is defined by the service provider for these capabilities. It includes processors, operating systems, service software, and standards profiles that include network diagrams showing communication links with bandwidth, processor locations, and capacities to include hardware builds versus schedule and costs. [DOD 8020.1-M, Appendix J specifically paragraph 5(14)c, Table J-2] DISA CFS
archive, noun A collection of data, normally used to hold data that has been superseded, or is rarely accessed. CEN/TC 287
archive, verb Transfer data to an archive. CEN/TC 287
Arctic Circle The geographical parallel having a north latitude equal to the complement of the declination of the summer solstice. The obliquity of the ecliptic is steadily changing so that the summer solstice is not a point of fixed declination, and the Arctic Circle, as defined, is not a line of fixed position. When the Arctic Circle is to be shown on a map, however, it is desirable that it be treated as a line of fixed position, and that a conventional value be adopted for its latitude. For this value 66 33' north latitude is used. Also called north polar circle. HDBK-850
area Bounded, contiguous 2-dimensional geometric primitive, delimited by one outer non-intersecting boundary and zero or more non-nested non-intersecting inner boundaries. CEN/TC 287
area A level of spatial measurement referring to a two-dimensional defined space. A polygon on the earth as projected onto a horizontal plane is an example of an area. HDBK-850
area analysis intelligence Intelligence data relative to a specific geographic area. HDBK-850
area command A unified command that has geographic responsibilities. Operations include all aspects of military capability (air, land, sea and special operations). Five area commands have been designated (i.e., United States Atlantic Command (USACOM), United States Central Command (USCENTCOM), United States European Command (USEUCOM), United States Pacific Command (USPACOM) and United States Southern Command (USSOUTHCOM)). USIS 95
area coverage 1. Complete coverage of an area by aerial photography having parallel overlapping flight lines and stereoscopic overlap between exposures in the line of flight. 2. When applied to shoran, the term implies that recorded shoran distances are available for each exposure. 3. Complete coverage of a geographical area by maps or other graphic material. HDBK-850
area grid A geometrical system of dividing Earth surface areas into subareas suitable for targeting and accounting purposes. USIS 95
area limitation products Multispectral based and other imagery products, special purpose charts depicting potential strategic relocatable target (SRT) deployment areas and studies and reports analyzing actual and potential SRT operations and tactics. USIS 95
area of intelligence responsibility An area allocated to a commander, in which he is responsible for the provision of intelligence, within the means at his disposal. USIS 95
area of interest (AOI) Military term denoting an area beyond reach of organic weapons but from which a threat could approach the operating unit within a specified time, dependent on the type of unit. USIS 95
area of operations That portion of an area of war necessary for military operations and for the administration of such operations. USIS 95
area of responsibility (AOR) 1. A defined area of land in which responsibility is specifically assigned to the commander of the area for the development and maintenance of installations, control of movement and the conduct of tactical operations involving troops under his control along with parallel authority to exercise these functions. 2. In naval usage, a predefined area of enemy terrain for which supporting ships are responsible for covering by fire on known targets or targets of opportunity and by observation. USIS 95
area pattern screen A photographic negative or positive containing repetitively arranged small feature symbols which have been designed to present a visual portrayal of a map or chart areal feature; i.e., swamp, orchard, sand, etc. See also contact screen; line pattern. HDBK-850
Area Requirements and Product Status (ARAPS) Data base which describes DMA's [NIMA's] customer area requirements and forecasts for various MC&G products. ARAPS is used by DMA [NIMA] to plan production schedules. HDBK-850
area survey 1. A survey of areas large enough to require a network of control stations. 2. An extension and densification of survey control. HDBK-850
area target (JCS) A target consisting of an area rather than a single point. See also pinpoint target. HDBK-850
area target A target with an area defined by boundary points, such as nodes and vertices. USIS 2-1.1
Area Target Identifier (ATI) The six character identifier code for area targets. The first character indicates the target type (D for DSA, L for LOC etc.); the next five characters are a sequential area identifier number assigned by RMS. USIS 2-1.1
area triangulation A system of triangulation designed to progress in every direction. Area triangulation is executed to provide survey control points over an area, as of the city or county; or for filling in the areas between arcs of triangulation which form a network extending over a county or state. See also survey net; triangulation net. HDBK-850
area weighted average resolution (AWAR) A single average value for the resolution over the picture format for any given focal plane. HDBK-850
areal feature A topographic feature, such as sand, swamp, vegetation, etc., which extends over an area. It is represented on the published map or chart by a solid or screened color, by a prepared pattern of symbols, or by a delimiting line. 2. (digital mapping) Any area enclosed by a delimiting line that has any unique characteristic, e.g., forest, residential, etc. 3. (raster) A block of grid cells which represent a homogeneous portion of the earth. HDBK-850
areodesy (JCS) That branch of mathematics which determines by observations and measurements, the exact positions of points and the figures and areas of large portions of the surface of the planet Mars, or the shape and size of the planet Mars. HDBK-850
argument In astronomy, an angle or arc, as in argument of perigee. HDBK-850
argument of latitude In celestial mechanics, the angular distance measured in the orbit plane from the ascending node to the orbiting object; the sum of the argument of perigee and the true anomaly. HDBK-850
argument of perigee An orbital element defined as the angle at the center of attraction from the ascending node to the perigee point measured in the direction of motion of the orbiting body. HDBK-850
arithmetic encoding A patented, proprietary mathematical entropy encoding process for compression of data. May provide better compression than Huffman encoding. Multimedia
Army Battle Command System (ABCS) An integration of Army battlefield automation and communication systems which functionally link strategic, operational and tactical headquarters by employing a mix of fixed and semi-fixed installations and mobile networks. This system is also to be interoperable with theater, joint and combined C2 systems. DII MP
array flight test Refers to equipment used to flight test components during the development of an imaging system. USIS 95
artificial asteroid A man-made object placed in orbit about the Sun. HDBK-850
artificial Earth satellite A man-made Earth satellite, as distinguished from the Moon. HDBK-850
artificial horizon (JCS) See attitude indicator. HDBK-850
artificial monument A relatively permanent object used to identify the location of a survey station or corner. Objects include man-made structures such as abutments, stone markers, concrete markers, and railroad rails. HDBK-850
artwork prediction See experience radar prediction. HDBK-850
Arundel method A combination of graphical and analytical methods, based on radial triangulation, for point-by-point topographic mapping from aerial photographs. HDBK-850
ascending node That point at which a planet, planetoid, or comet crosses the ecliptic from south to north, or a satellite crosses the equator of its primary from south to north. Opposite of descending node. Also called northbound node. HDBK-850
ascending pass The portion of a vehicle path around the Earth during which the vehicle is flying north relative to the poles. USIS 95
ascending vertical angle See angle of elevation. HDBK-850
ascensional difference The difference between right ascension and oblique ascension. HDBK-850
Asia-Pacific Center for Security Studies (APC) The APC is a research, conference, and study center with a non-warfighting mission to foster understanding, cooperation, and study of security-related issues among military and civilian representatives of the United States and other Asia-Pacific nations. The Center provides a focal point where national officials, decision makers, and policy makers can gather to exchange ideas, explore pressing issues and achieve a greater understanding of the challenges that shape the security environment of the Asia-Pacific region. Its focus is on the increasingly complex interrelationships of the military, economic, political, and diplomatic policies relevant to regional security issues. The APC is located in Honolulu, HI. PACOM Web Site
aspect Horizontal direction in which a slope faces, commonly expressed as the direction clockwise from north. HDBK-850
aspect categories Classification of an aspect into a grouping based on cardinal compass direction or a range of degrees. HDBK-850
aspect change (JCS) The different appearance of a reflecting object viewed by radar from varying directions. It is caused by the change in the effective reflecting area of the target. HDBK-850
aspect ratio The numerical ratio of picture width to height. HDBK-850
aspects The apparent positions of celestial bodies relative to one another; particularly the apparent positions of the Moon or a planet relative to the Sun. HDBK-850
aspherical lens A lens in which one or more surfaces depart from a true spherical shape. HDBK-850
assault landing model A special form of assault model designed specifically for planning amphibious landings. Also called amphibious assault landing model. See also assault models. HDBK-850
assault models Large-scale models giving a particular representation of vegetation, lesser landforms, prominent man-made features, and a detailed representation of specific or sensitive objectives such as airfields, radar installations, and the like. These models emphasize the aspects of objects as seen from surface approach . HDBK-850
Assigned Directory {DII COE} The unique directory assigned to a segment at segment registration time that is to be the segment's home directory. A segment is normally completely contained within its assigned directory and may not modify any files outside its assigned directory without going through facilities provided by the COE. DII COE IRTS
associated Legendre function A solution of the Legendre equation, which is a special case of the Laplace equation, in the form of a power series of a special kind; used in the spherical harmonic expansion of the gravitational potential. HDBK-850
association Property describing a relationship between objects. CEN/TC 287
association type A class of associations. CEN/TC 287
assumed ground elevation The elevation assumed to prevail in the local area covered by a particular photograph or group of photographs. Used especially to denote the elevation assumed to prevail in the vicinity of a critical point, such as a peak or other feature having abrupt local relief. HDBK-850
assumed latitude The latitude at which an observer is assumed to be located for an observation or computation, as the latitude of an assumed position or the latitude used for determining the longitude by time sight. HDBK-850
assumed longitude The longitude at which an observer is assumed to be located for an observation or computation, as the longitude of an assumed position or the longitude used for determining the latitude by meridian altitude. HDBK-850
assumed plane coordinates A local plane coordinate system set up at the convenience of the surveyor. The reference axes are usually assumed so that all coordinates are in the first quadrant. The y-axis may be in the direction of astronomic north, geodetic north, magnetic north, or an assumed north. HDBK-850
Assurance {AIS Security} A measure of confidence that the security features and architecture of an Automated Information System (AIS) accurately mediate and enforce the security policy. Reliance on the security features of an AIS to protect classified or unclassified-but-sensitive information and restrict user access requires that the features be tested to ensure that the security policy is enforced and may not be circumvented during AIS operation. [DISA/D2] DISA CFS
assurance level See confidence interval. HDBK-850
assured access Guaranteed access to target data in response to user needs. USIS 95
assured collection The ability to collect over a desired target or area at any time of day. USIS 95
astatized gravimeter A gravimeter, sometimes referred to as unstable, where the force of gravity is maintained in an unstable equilibrium with the restoring force. The instability is provided by the introduction of a third force which intensifies the effect of any change in gravity from the value in equilibrium. HDBK-850
ASTERIX Automated analyst support tools (word processing, spreadsheets, graphics, etc.). Part of the Joint Deployable Intelligence Support System (JDISS) suite. A standard application found on most SUN/UNIX workstations. USIS 95
asteroid A minor planet; one of the many small celestial bodies revolving around the Sun, most of the orbits being between those of Mars and Jupiter. Also called minor planet; planetoid. See also artificial asteroid. HDBK-850
astigmatism An aberration affecting the sharpness of images for objects off the axis in which the rays passing through different meridians of the lens come to a focus in different planes. Thus, an extra-axial point object is imaged as two mutually perpendicular short lines located at different distances from the lens. HDBK-850
astigmatizer A lens which introduces astigmatism into an optical system. Such a lens is so arranged that it can be placed in or removed from the optical path at will. In a sextant, an astigmatizer may be used to elongate the image of a celestial body into a horizontal line. HDBK-850
astre fictif Any of several fictitious stars assumed to move along the celestial equator at uniform rates corresponding to the speeds of the several harmonic constituents of the tide-producing force. Each astre fictif crosses the meridian at the instant the constituent it represents is at a maximum. HDBK-850
astro compass (JCS) An instrument used primarily to obtain true heading or true bearing by reference to celestial bodies. HDBK-850
astrodynamics The practical application of celestial mechanics, astroballistics, propulsion theory, and allied fields to the problem of planning and directing the trajectories of space vehicles. HDBK-850
astrogeodetic datum orientation The position of a reference ellipsoid in relation to the geoid in a specified area of a geodetic network. It may be expressed by the astrogeodetic deflection and geoidal height at the datum point or by an astrogeodetic geoid chart of the area. HDBK-850
astrogeodetic deflection The angle at a point between the normal to the geoid and the normal to the ellipsoid of an astrogeodetically oriented datum. Also called relative deflection. HDBK-850
astrogeodetic leveling A method to determine variations in the separation of the geoid and the ellipsoid using astrogeodetic deflections. Also called astronomic leveling; geoidal height profile. HDBK-850
astrogeodetic undulations The separation between an astrogeodetic geoid, defined for a particular datum, and a specified ellipsoid surface. See also geoidal height. HDBK-850
astrograph 1. A device for projecting a set of precomputed altitude curves onto a chart or plotting sheet, the curves moving with time such that if they are properly adjusted, they will remain in the correct position on the chart or plotting sheet. 2. A telescope, usually of moderate focal length, which is designed specifically for the purpose of accurately recording the positions of celestial objects by photographic means. HDBK-850
astrograph mean time A form of mean time, used in setting an astrograph. Astrograph mean time 1200 occurs when the local hour angle of Aries is 0. HDBK-850
astrographic position See astrometric position. HDBK-850
astrogravimetric leveling A concept whereby a gravimetric map is used for the interpolation of the astrogeodetic deflections of the vertical to determine the separation of the ellipsoid and the geoid in studying the figure of the Earth. HDBK-850
astrogravimetric points Astronomic positions corrected for the deflection of the vertical by gravimetric methods. HDBK-850
astrolabe 1. (general) Any instrument designed to measure the altitudes of celestial bodies. 2. (surveying) An instrument designed for very accurate celestial altitude measurements. See also equiangulator; pendulum astrolabe; planispheric astrolabe; prismatic astrolabe. HDBK-850
astrometric position The position of a heavenly body (or space vehicle) on the celestial sphere corrected for aberration but not for planetary aberration. Astrometric positions are used in photographic observation where the position of the observed body can be measured in reference to the positions of comparison stars in the field of the photograph. Also called astrographic position. See also apparent position. HDBK-850
astrometry The branch of astronomy dealing with the geometric relations of the celestial bodies and their real and apparent motions. The techniques of astrometry, especially the determination of accurate position by photographic means, are used in tracking satellites and space probes. HDBK-850
astronomic Of or pertaining to astronomy, the science which treats of heavenly bodies, and the arts based on that science. HDBK-850
astronomic arc The apparent arc described above (diurnal arc) or below (nocturnal arc) the horizon by the Sun or another celestial body. HDBK-850
astronomic azimuth The angle between the astronomic meridian plane of the observer and the plane containing the observed point and the true normal (vertical) of the observer, measured in the plane of the horizon, preferably clockwise from north. HDBK-850
astronomic azimuth mark A marked point whose astronomic azimuth from a survey station is determined from direct observations on a celestial body. The mark may be a lamp or illuminated target placed especially for the purpose; it may be a well defined illuminated point on a permanent structural point. HDBK-850
astronomic bearing See true bearing. HDBK-850
astronomic constants The elements of the orbits of the bodies of the solar system, their masses relative to the Sun, their size, shape, orientation, rotation, and inner constitution, and the velocity of light. See also system of astronomic constants. HDBK-850
astronomic control A network of control stations the positions of which have been determined by astronomic observation. Latitudes and longitudes thus determined will normally differ from the geodetic latitudes and longitudes of the same stations by amounts corresponding to components of the deflection of the vertical. HDBK-850
astronomic coordinates 1. Quantities defining a point on the surface of the Earth, or of the geoid, in which the local direction of gravity is used as a reference. Also called geographic coordinates; gravimetric coordinates; terrestrial coordinates. 2. The coordinates of an astronomic body referred to a given equinox. HDBK-850
astronomic date Designation of epoch by year, month, day, and decimal fraction. For example, the astronomic date of December 21, 1978, 18h UTC (universal time coordinated) is 1978 December 21.75 UTC. The astronomic date is also used in connection with the other time systems. The system commences every calendar year at 0h on December 31 of the previous year. This epoch is denoted by January 0.0. HDBK-850
astronomic day A mean solar day beginning at mean noon, 12 hours later than the beginning of the civil day of the same date. Astronomers now generally use the civil day. HDBK-850
astronomic equator The line on the surface of the Earth whose astronomic latitude at every point is 0. Due to the deflection of the plumb line, the astronomic equator is not a plane curve. However, the verticals at all points on it are parallel to one and the same plane, the plane of the celestial equator; that is, the zenith at every point on the astronomic equator lies in the celestial equator. When the astronomic equator is corrected for station error, it becomes the geodetic equator. Also called terrestrial equator. See also geodetic equator. HDBK-850
astronomic latitude The angle between the plumb line and the plane of celestial equator. Also defined as the angle between the plane of the horizon and the axis of rotation of the Earth. Astronomic latitude applies only to positions on the Earth and is reckoned from the astronomic equator (0) north and south through 90. Astronomic latitude is the latitude which results directly from observations of celestial bodies, uncorrected for deflection of the vertical. HDBK-850
astronomic leveling See astrogeodetic leveling. HDBK-850
astronomic longitude The angle between the plane of the celestial meridian and the plane of an initial meridian, arbitrarily chosen. Astronomic longitude is the longitude which results directly from observations on celestial bodies, uncorrected for deflection of the vertical. HDBK-850
astronomic meridian A great circle of the celestial sphere intersecting the north and south celestial poles. The local astronomic meridian is that meridian which intersects the zenith of the point. HDBK-850
astronomic meridian plane A plane that contains the vertical of the observer and is parallel to the instantaneous rotation axis of the Earth. HDBK-850
astronomic parallel A line on the surface of the Earth which has the same astronomic latitude at every point. Because the deflection of the vertical is not the same at all points on the Earth, an astronomic parallel is an irregular line, not lying in a single plane. See also astronomic equator. HDBK-850
astronomic position 1. A point on the Earth whose coordinates have been determined as a result of observations of celestial bodies. The expression is usually used in connection with positions on land determined with great accuracy for survey purposes. 2. A point on the Earth, defined in terms of astronomic latitude and longitude. HDBK-850
astronomic refraction The apparent displacement of an object that results from light rays from a source outside the atmosphere being bent in passing through the atmosphere. This results in all objects appearing to be higher above the horizon than they actually are. The magnitude of this displacement is greater when the object is near the horizon and decreases to a minimum assumed to be zero when the object is at the zenith. Also called astronomic refraction error; celestial refraction. See also atmospheric refraction; refraction. HDBK-850
astronomic refraction error See astronomic refraction. HDBK-850
astronomic station A point on the Earth whose position has been determined by observations on celestial bodies. HDBK-850
astronomic surveying The celestial determination of latitude and longitude. Separations are calculated by computing distances corresponding to measured angular displacements along the reference spheroid. HDBK-850
astronomic theodolite See altazimuth instrument. HDBK-850
astronomic tidal constituent See constituent. HDBK-850
astronomic time Solar time in a day (astronomic day) that begins at noon. Astronomic time may be either apparent solar time or mean solar time. Since 1925, civil time is generally used instead of astronomic time. HDBK-850
astronomic transit See transit, definition 4. HDBK-850
astronomic triangle The navigational triangle, either terrestrial or celestial, used in the solution of celestial observations. Referring to the celestial sphere it is the triangle formed by arcs of great circles connecting the celestial pole, the zenith, and a celestial body. The angles of the astronomic triangles are: at the pole, the hour angle; at the celestial body, the parallactic angle; at the zenith, the azimuth angle. The sides arc: pole to zenith, the colatitude; zenith to celestial body, the zenith distance; and celestial body to pole, the polar distance. Also called PZS triangle. HDBK-850
astronomic unit A unit of length equal to 149,600,000 kilometers (adopted 1960) used for measuring distances within the solar system. This distance approximates the mean distance of the Earth from the Sun. HDBK-850
astronomic year See tropical year. HDBK-850
astronomical coordinates Astronomical latitude and astronomical longitude of a given point, with or without orthometric height . CEN/TC 287
astronomical latitude Angle from the equatorial plane to the direction of gravity through the given point, northwards treated as positive. CEN/TC 287
astronomical longitude Angle from the zero meridian plane to the celestial meridian plane of the given point. An astronomical concept beyond the scope of this standard. CEN/TC 287
asymmetry angle The angle between the bisector of the convergence angle of two stereo images and the projection of the vector orthogonal to the tangent plane at the ground point onto the slant plane containing the two line-of-sight vectors. (The second line is the perpendicular projection on the slant plane of a local vertical line through the same ground point.) The asymmetry angle is defined at all points in the overlap region between two images, and the asymmetry angle normally varies within a stereo overlap region. USIS 95
asymmetry of object (target) Lack of symmetry in the visible aspect of an object as seen from a particular point of observation. A square or rectangular pole may so face the observer that the line bisecting its tangents does not pass through its geometric center. With a square cupola or tower, the error resulting from observing tangents and taking a mean may be quite large. The error caused by asymmetry of an observed object is of the same character and requires the same treatment as the error resulting from observing an eccentric object. See also phase. HDBK-850
asymptote A straight line or curve which some curves of infinite length approach but never reach. HDBK-850
asynchronous A communications method in which data are sent as soon as they are ready, as opposed to methods in which data are sent at fixed intervals; requires start and stop bits to separate characters. [Joint Pub 6-02.1] DISA CFS
asynchronous transfer mode (ATM) A high-speed multiplexing and switching method utilizing fixed-length cells of 53 octects to support multiple types of traffic. Note: ATM, specified in international standards, is asynchronous in the sense that cells carrying user data need not be periodic. Compare with synchronous transfer mode. FED STD 1037C
Atlantic Command See United States Atlantic Command (USACOM). ACOM Web Site
Atlantic Command Deployable Intelligence System Provides fully interactive connectivity for a mobile user to the CINCLANT Intelligence Data Handling System and to global sensitive compartmented information/Defense Secure Network 3/DoDIIS network using nondedicated communications. USIS 95
Atlantic Command Intelligence Data Handling System The main computer system used in part to support imagery interpretation. USIS 95
Atlantic Fleet Detachment to USSOUTHCOM See United States Atlantic Fleet (LANTFLT). LANTFLT Web Site
atlas grid A reference system that permits the designation of the location of a point or an area on a map, photo, or other graphic in terms of numbers and letters. Also called alphanumeric grid. HDBK-850
atmosphere (JCS) The air surrounding the Earth. See also ionosphere; stratosphere; tropopause; troposphere. HDBK-850
atmospheric correction The removal of the atmospheric effects from a remote sensing data set such that the data set simulates one that would be obtained if the data were collected in an environment that had no atmosphere (e.g., a vacuum, or a measurement taken in space which did not have to go through the earth's atmosphere). OGC RFI
atmospheric drag A major perturbation of close artificial satellite orbits caused by the resistance of the atmosphere. The secular effects are decreasing eccentricity, major axis, and period. Also called drag. HDBK-850
atmospheric refraction The refraction of light passing through the Earth's atmosphere. Atmospheric refraction includes both astronomic refraction and terrestrial refraction. HDBK-850
atomic time Time interval based on the frequency of atomic oscillators. HDBK-850
attempt The aiming and activating of an imagery sensor at a target whether or not the resulting image satisfies the imaging requirement. USIS 95
attenuation (JCS) Decrease in intensity of a signal, beam, or wave as a result of absorption of energy and of scattering out of the path of a detector, but not including the reduction due to geometric spreading, i.e., the inverse square of distance effect. HDBK-850
attitude 1. (JCS) The position of a body as determined by the inclination of the axes to some frame of reference. If not otherwise specified, this frame of reference is fixed to the Earth. 2. Grid bearing relative to the long axis of the target 3. (photogrammetry) The angular orientation of a camera, or of the photograph taken with that camera, with respect to some external reference system. Usually expressed as tilt, swing, and azimuth; or roll, pitch, and yaw. HDBK-850
attitude The angular orientation of a remote sensing system with respect to a geographical reference system. USIS 95
attitude indicator (JCS) An instrument which displays the attitude of the aircraft by reference to sources of information which may be contained within the instrument or be external to it. When the sources of information are self-contained. The instrument may be referred to as an artificial horizon. HDBK-850
attribute A property or characteristic. C4ISR AF
attribute A named property of an object. An attribute belongs to a certain attribute type and has a value taken from the domain belonging to the attribute type. CEN/TC 287
attribute An identifiable association between an object and a value. An attribute A is made visible to clients as a pair of operations: get_A and set_A. Readonly attributes only generate a get operation. CORBA 2.2
attribute A characteristic of a site or phenomenon. May be physical, social, economic or titular in nature. For example, road types and road names are road attributes. HDBK-850
attribute A property which describes a geometrical, topological, thematic, or other characteristic of an entity ISO/TC 211
attribute A type of characteristic or property associated with an entity. USIGS/CDM-A
attribute data Descriptive information about features or elements of a database. For a database feature like census tract, attributes might include many demographic facts including total population, average income, and age. In statistical parlance, an attribute is a "variable," whereas the database feature represents an "observation" of the variable. OpenGIS Guide
attribute domain A range or set of valid values for a metadata element. ISO/TC 211
attribute identifier A three-alphanumeric character designator of an attribute. HDBK-850
attribute tagging The process of assigning an attribute to a particular feature. HDBK-850
attribute type A class of attributes. CEN/TC 287
attribute value A specific quality of quantity assigned to an attribute. HDBK-850
attribute value A value assigned to a feature attribute. ISO/TC 211
audio conferencing Teleconferencing that employs voice communications, usually accomplished using standard telephone lines. When more than one person is in a single location, speakerphones or special audio conferencing terminal equipment is employed. When more than two locations are involved, audio conferencing network equipment or services may be employed to improve the quality of the conference. Multimedia
audiographic Documents and still image data (graphics, text, drawings, photos) with accompanying audio. Multimedia
audiovisual Audio and/or video capability. Multimedia
augmentation The apparent increase in the semidiameter of an azimuth celestial body as its altitude increases, due to the reduced distance from the observer. The term is used principally in reference to the Moon. HDBK-850
augmentation correction A correction due to augmentation, particularly that sextant altitude correction due to the apparent increase in the semidiameter of a celestial body as its altitude increases. HDBK-850
augmenting factor A factor used in connection with the harmonic analysis of tides or tidal currents to allow for the difference between the times of hourly tabulation and the corresponding constituent hours. HDBK-850
austral Of or pertaining to south. HDBK-850
Australian Centre for Remote Sensing (ACRES) The ACRES is Australia's major satellite Remote Sensing organisation, which was established as the Australian Landsat Station in 1979. ACRES is a business unit of the Australian Surveying and Land Information Group (AUSLIG), Department of Industry, Science and Tourism. ACRES mission is to support Australia's environmental management and economic and social development by fostering geographic information solutions in the field of remote sensing. ACRES primary functions are to acquire, archive, process and distribute remotely sensed data acquired from earth observation satellites for both scientific and operational applications. ACRES operates two facilities, the Data Acquisition Facility (DAF) in Alice Springs, Australia, and the Data Processing Facility (DPF) in Fernhill Park, Canberra, Australia. AUSLIG Web Site
Australian National Spheroid A reference spheroid having the following dimensions: semimajor axis-6,378,160.0 meters; and a flattening or ellipticity of 1/298.25. HDBK-850
authalic (equal-area) latitude A latitude based on a sphere having the same area as the spheroid, and such that areas between successive parallels of latitude are exactly equal to the corresponding areas on the spheroid. Authalic latitudes are used in the computation of equal-area map projections. HDBK-850
authalic map projection An equal-area map projection. HDBK-850
authentication 1. To verify the identity of a user, device, or other entity in a computer system, often as a prerequisite to allowing access to resources in a system. 2. To verify the integrity of data that have been stored, transmitted, or otherwise exposed to possible unauthorized modification. JTA 2.0
authoring A process implemented by a "developer" where a multimedia application is "programmed" into a series of icons, menus, hypermedia, etc. Popular authoring tools include Macromedia Director, Authorware, AimTech's IconAuthor, and Microsoft's Visual Basic. Multimedia
authoring system Software that helps developers create multimedia programs or presentations without requiring the painstaking skills involved in traditional programming. Multimedia
authorized frequency A radio frequency allocated and assigned to a transmission link for continuing use. [Joint Pub 6-02.1] DISA CFS
auto reflection The focusing of an autocollimating theodolite on the surface of the mirror or prism rather than focused at infinity. The image seen is on the face of the reflector and the gauss image will follow the motion of the reticule. Whereas, in autocollimation, the instrument is focused at infinity and the gauss image moves in opposite directions to the reticule. HDBK-850
autocollimation (surveying) The procedure used to determine or transfer azimuth to an instrument or device. This procedure requires use of a specially adapted telescope, capable of bisecting the real image of its own reticule as reflected from a mirror or Porro prism. When such bisection is accomplished, the line of sight of the telescope is perpendicular to the face of the mirror or apex edge of the prism. HDBK-850
autocollimator A collimator provided with a means of illuminating its cross hairs so that, when a reflecting plane is placed normal to the emergent light beam, the reflected image of the cross hairs appears to be coincident with the cross hairs themselves. This device is used in calibrating optical and mechanical instruments and transferring direction. HDBK-850
autofocus rectifier A precise, vertical photoenlarger which permits the correction of distortion in an aerial negative caused by tilt. The instrument's operations are motor driven and are interconnected by mechanical linkages to insure automatically maintained sharp focus. HDBK-850
Automated Air Facilities Information File (AAFIF) AAFIF is a text file which contains evaluated information on aircraft movement surfaces (runways, taxiways, aprons, etc.), facilities, support equipment, services, operations, navaids/communications, transportation and other items for approximately 43,000 airfields worldwide. Continental United States (CONUS) airfields are maintained with fewer subcategories due to availability of data from the Federal Aviation Adminstration (FAA). NIMA LOP
Automated Command and Control Information System (ACCIS) A NATO ADP system that supports command and control for Allied Command Europe (ACE), its major subordinate commands (AFCENT, AFNORTH, AFSOUTH, etc.), and principal subordinate commands (CENTAG, NORTHAG, AAFCE, etc.). [Joint Pub 6-02.1] DISA CFS
automated data processing 1. Data processing largely performed by automatic means. 2. That branch of science and technology concerned with methods and techniques relating to data processing largely performed by automatic means. USIS 95
Automated Data Processing (ADP) Recording, filing, computing, and producing of data by means of electronic computers and associated auxiliary equipment. [U.S. Navy ADP Glossary] DISA CFS
Automated Data Processing Equipment (ADPE) Any equipment or interconnected system or subsystems of equipment that is used in the automatic acquisition, storage, manipulation, management, movement, control, display, switching interchange, transmission, or reception, of data or information by a Federal Agency, or under a contract with a Federal Agency, which requires the use of such equipment; or requires the performance of a service; or the furnishing of a product that is performed or produced making significant use of such equipment. Such term includes computers; ancillary equipment; software, firmware, and similar procedures; services, including support services; and related resources, as defined by the Administrator for General Services (DODD 8000.1, 27 Oct 92 and Pub. L. No. 99-591 (1986)). DISA CFS
Automated Data Processing System (ADPS) An aggregation of required software and the support resources (ADPE, manpower, communications, services, and facilities). The ADPS includes one or more automated data systems (ADS) and generally is associated with a distinct suite of hardware. The configuration of ADPS can be all ADSs and their supporting resources at a single activity, and ADS and its associated resources that support a single function at one or more activities, or an aggregation of types of activity with a common function and/or mission. [Joint Pub 6-02.1] DISA CFS
automated image examination A process of limited data extraction (detection, categorizing, identification) from imagery with limited or no human aid. Automatic (i.e. machine) recognition of targets in images. Includes automatic target recognition and image understanding. USIS 95
Automated Imagery Analyst Workstation A DIA-developed workstation that interfaces personal computers, HFO-4 light tables, and imagery digitizing technology to provide the imagery analyst with a sophisticated hardcopy/softcopy exploitation support tool. USIS 95
automated imposition machine (miso, misomex) A step and repeat machine used to expose multiple images onto either a printing plate or sheet of film. HDBK-850
automated information system (AIS) A combination of computer hardware and software, data, or telecommunications, that performs functions such as collecting, processing, transmitting, and displaying information. Excluded are computer resources, both hardware and software, that are: physically part of, dedicated to, oressential in real time to the mission performance of weapon systems. DoDD 5000.1
Automated Mapping / Facilities Management (AM/FM) A computer aided mapping system which stores annotation and limited attribute data. AM/FM systems are commonly used by the utility industries and municipalities. HDBK-850
Automated Message Handling System (AMHS) A combination of hardware and software components that automate the process and management of messages from origination to destination (writer-to-reader). These components are used to provide advanced processing of large volumes of messages. [DISA/D2] DISA CFS
Automated Secure Voice Communications A worldwide, switched, secure voice network developed to fulfill DoD long-haul, secure voice requirements. USIS 95
automated tools Software performing a sequence of operations to assist the user in achieving a goal (e.g., within graphics software, application code, functions that align objects, smooth curves, or draw circles). [HCI Style Guide] DISA CFS
automatic clipping/joining The system capability for copying small portions of a data base for movement and placement elsewhere in the data base without operator intervention. HDBK-850
automatic cloud edit Computer scan of imagery to determine total cloud cover. USIS 95
Automatic Digital Annotation System (ADAS) A system used to record camera position and other information on film at time of exposure. HDBK-850
Automatic Digital Network (AUTODIN) A worldwide Defense Communications System (DCS) common-user network that provides automatic message and data routing and switching service for DOD and certain non-DOD subscribers. [Joint Pub 6-02.1] DISA CFS
automatic feature extraction The automatic delineation and attribution of features. The function is obtained through computer vision tools and a knowledge base system. USIS 95
automatic gage See self-registering gage. HDBK-850
automatic level See pendulum level. HDBK-850
automatic polygon centroid calculation The system capability for determining the center of a polygon area without operator intervention. Usually associated with automatic label placement. HDBK-850
automatic rectifier Any rectifier which employs mechanisms to insure automatic fulfillment of the lens law and the Scheimpflug condition. These devices, called inversors, provide a mechanical solution for the linear and angular elements of rectification. Essentially, this class of rectifier is a tilt analyzer using inversors to solve for the optical geometric elements needed for sharp focus. HDBK-850
automatic rod See tape rod. HDBK-850
automatic snapping The system capability for completing a line segment whose end approaches a predefined threshold of closeness to an intersection or node, without any operator intervention. HDBK-850
automatic target recognition Using computers to recognize targets to aid imagery exploitation efforts. USIS 95
automatic terrain extraction A process based on a correlation technique (hierarchical relaxation) in which a widely spaced grid of approximate elevation values, obtained with 1:32 Reduced Resolution Data Set (RRDS) imagery, is successively refined until a sufficiently dense support grid is available. USIS 95
Automatic Terrain Recognition And Navigation (ATRAN) A navigation system which depends upon the correlation of terrain images appearing on a radar cathode-ray tube with previously prepared maps or simulated radar images of the terrain. HDBK-850
autoradar plot See chart comparison unit. HDBK-850
autoreducing tachymeter A class of tachymeter by which horizontal and height distances are read simultaneously. Horizontal distance is the intercept multiplied by 100 and the vertical distance is the midwire (curve) multiplied by a factor which appears in the optics. HDBK-850
autoscreen film A photographic film embodying a halftone screen which automatically produces a halftone negative from continuous tone copy. HDBK-850
autumnal equinox That point of intersection of the ecliptic and the celestial equator occupied by the Sun as it changes from north to south declination, about 23 September. Also called first point of Libra; September equinox. HDBK-850
auxiliary contour See supplementary contour. HDBK-850
auxiliary guide meridian Where guide meridians have been placed at intervals exceeding the distance of 24 miles, and new governing lines are required, a new guide meridian is established, and a local name is assigned, such as "Twelfth Auxiliary Guide Meridian West," or "Grass Valley Guide Meridian." Auxiliary guide meridians are surveyed, in the same manner as guide meridians. See also guide meridian; principal meridian. HDBK-850
auxiliary meander corner An auxiliary meander corner is established at a suitable point on the meander line of a lake lying entirely within a quarter section or on the meander line of an island falling entirely within a section and which is found to be too small to subdivide. A line is run connecting the monument to a regular corner on the section boundary. HDBK-850
auxiliary station Any station connected to the main scheme net and dependent upon it for the accuracy of its position. HDBK-850
availability The probability that system functional capabilities are ready for use by a user at any time, where all time is considered, including operations, repair, administration, and logistic time. Availability is further defined by system category for both routine and priority operations. [JOPES ROC] DISA CFS
average deviation In statistics, the average or arithmetic means of the deviations, taken without regard to sign, from some fixed value, usually the arithmetic mean of the data. Also called mean deviation. HDBK-850
average terrestrial pole The average position of the instantaneous pole of rotation of the Earth, averaged over a specified time period. See also conventional international origin. HDBK-850
averaging device A device for averaging a number of readings, as on a bubble sextant. HDBK-850
aviation combat element (ACE) The Marine air-ground task force (MAGTF) element that is task organized to provide all or a portion of the functions of Marine Corps aviation in varying degrees based on the tactical situation and the MAGTF mission and size. These functions are air reconnaissance, antiair warfare, assault support, offensive air support, electronic warfare, and control of aircraft and missiles. The ACE is organized around an aviation headquarters and varies in size from a reinforced helicopter squadron to one or more Marine aircraft wing(s). It includes those aviation command (including air control agencies), combat, combat support, and combat service support units required by the situation. Normally, there is only one ACE in a MAGTF. JPUB 1-02
axis See camera axis; collimation axis; coordinate axes; equatorial axis; fiducial axes; horizontal axis; major axis; minor axis; optical axis; polar axis; semimajor axis; semiminor axis; spirit level axis; topple axis; transverse axis; vertical axis; x-axis; y-axis; z-axis. HDBK-850
axis of homology The intersection of the plane of the photograph with the horizontal plane of the map or the plane of reference of the ground. Corresponding lines in the photograph and map planes intersect on the axis of homology. Also called the axis of perspective; map parallel; perspective axis. See also ground parallel. HDBK-850
axis of lens See optical axis. HDBK-850
axis of level See spirit level axis. HDBK-850
axis of perspective See axis of homology. HDBK-850
axis of the level bubble See spirit level axis. HDBK-850
axis of tilt A line through the perspective center perpendicular to the principal plane. The axis of tilt could be any of several lines in space (e.g., the isometric parallel or the ground line), but the present definition is the only one which permits the concept of tilting a photograph without upsetting the positional elements of exterior orientation. HDBK-850
azimuth 1. (JCS) Quantities may be expressed in positive quantities increasing in a clockwise direction or in x-/y-coordinates where south and west are negative. They may be referenced to true north or magnetic north depending on the particular weapon system used. 2. (surveying) The horizontal direction of a line measured clockwise from a reference plane, usually the meridian. Also called forward azimuth to differentiate from back azimuth. 3. (photogrammetry) Azimuth of the principal plane. See also astronomic azimuth; azimuth by altitude; back azimuth; computed azimuth angle; direction method of determining astronomic azimuth; geodetic azimuth; grid azimuth; inertial azimuth; Laplace azimuth; magnetic azimuth; method of repetitions (determination of astronomic azimuth); micrometer method (determination of astronomic azimuth); normal section azimuth; true azimuth. HDBK-850
azimuth The direction, measured from 0-360 degrees, from which a satellite images a target. Measurement of azimuth begins and ends at the target's northernmost point. USIS 95
azimuth angle 1. (JCS) An angle measured clockwise in the horizontal plane between a reference direction and any other line. 2. (astronomy) The angle 180 or less between the plane of the celestial meridian and the vertical plane containing the observed object, reckoned from the direction of the elevated pole. In astronomic work, the azimuth angle is the spherical angle at the zenith in the astronomic triangle which is composed of the pole, the zenith, and the star. In geodetic work, it is the horizontal angle between the celestial pole and the observed terrestrial object. 3. (surveying) An angle in triangulation or in a traverse through which the computation of azimuth is carried. In a simple traverse, every angle may be an azimuth angle. Sometimes, in a traverse, to avoid carrying azimuths over very short lines, supplementary observations are made over comparatively long lines, the angles between which form azimuth angles. In triangulation, certain angles, because of their size and position in the figure, are selected for use as azimuth angles, and enter into the formation of the azimuth condition equation (azimuth equation). HDBK-850
azimuth angle The angle measured clockwise from true north in the Earth's tangent plane (measured at the target) of the line-of-sight from the target to the imaging satellite. USIS 95
azimuth bar See azimuth instrument. HDBK-850
azimuth by altitude An azimuth determined by solution of the navigational triangle with altitude, declination, and latitude given. HDBK-850
azimuth circle A ring designed to fit snugly over a compass or compass repeater, and provided with means for observing compass bearings and azimuths. HDBK-850
azimuth equation A condition equation which expresses the relationship between the fixed azimuths of two lines which are connected by triangulation or traverse. HDBK-850
azimuth error of closure See error of closure, definition 3. HDBK-850
azimuth instrument (magnetic) An instrument for measuring azimuths, particularly a device which fits over a central pivot in the glass cover of a magnetic compass. Also called azimuth bar; bearing bar. HDBK-850
azimuth line (photogrammetry) A radial line from the principal point, isocenter, or nadir point of a photograph, representing the direction to a similar point of an adjacent photograph in the same flight line; used extensively in radial triangulation. HDBK-850
azimuth mark A mark set at a significant distance from a triangulation or traverse station to mark the end of a line for which the azimuth has been determined, and to serve as a starting or reference azimuth for later use. See also astronomic azimuth mark; geodetic azimuth mark; Laplace azimuth mark. HDBK-850
azimuth resolution (JCS) The ability of radar equipment to separate two reflectors at similar ranges but different bearings from a reference point. Normally the minimum separation distance between the reflectors is quoted and expressed as the angle subtended by the reflectors at the reference point. HDBK-850
azimuth transfer Connecting, with a straight line, the nadir points of two vertical photographs selected from overlapping flights. HDBK-850
azimuth traverse A survey traverse in which the direction of the measured course is determined by azimuth and verified by back azimuth. To initiate this type of traverse it is necessary to have a reference meridian, either true, magnetic, or assumed. HDBK-850
azimuthal chart A chart on an azimuthal projection. Also called zenithal chart. HDBK-850
azimuthal equidistant chart A chart on the azimuthal equidistant map projection. HDBK-850
azimuthal equidistant map projection An azimuthal map projection on which straight lines radiating from the center or pole of projection represent great circles in their true azimuths from that center, and lengths along those lines are of exact scale. This projection is neither equal-area nor conformal. HDBK-850
azimuthal map projection A map projection on which the azimuths or directions of all lines radiating from a central point or pole are the same as the azimuths or directions of the corresponding lines on the sphere. Also called zenithal map projection. HDBK-850
azimuthal orthomorphic map projection See stereographic map projection. HDBK-850

Last Updated by Mark Owens 17 February 1999.