Index USIGS Glossary

-- 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 mark