Index USIGS Glossary

-- R --
Term Definition/Description Source
radar (JCS) Radio detection and ranging equipment that determines the distance and usually the direction of objects by transmission and return of electromagnetic energy. [This term is derived form the words "radio detection and ranging."] HDBK-850
radar altimeter An instrument used for determining aircraft flying height above terrain by measurement of time intervals between emission and return of electromagnetic pulses. HDBK-850
radar altitude The altitude of an aircraft or spacecraft as determined by a radar altimeter; thus, the actual distance from the nearest terrain feature. HDBK-850
radar chart A chart intended primarily for use with radar, or one suitable for this purpose. HDBK-850
radar clutter (JCS) Unwanted signals, echoes, or images on the face of the display tube which interfere with observation of desired signals. HDBK-850
radar correlation The process of electronically relating realtime radar images with stored digital data on the radar reflectance and position of terrain and fea'ures on the Earth's surface. It is used to provide positioning information to correct or check air navigation and guidance systems. HDBK-850
radar coverage (JCS) The limits within which objects can be detected by one or more radar stations. HDBK-850
radar fix point (RFP) The most significant radarscope ground feature for a given geographic area. The feature may be radar reflective or completely void of reflectivity to show contrast with the surrounding area; e.g., land/water or show/no show. Positioning data established for RFPs are used in offset aiming procedures or for enroute and final update of navigation systems. HDBK-850
radar horizon (JCS) The locus of points at which the rays from a radar antenna become tange'tial to the earth's surface. On the open sea this locus is horizontal but on land it varies according to the topographical features of the terrain. HDBK-850
radar imagery A radar image is formed by sending out radar pulses and recoding the energy that returns to the sensor. It is often referred to as "nonliteral" because an object may look different than it does visually. This imagery can be collected day or night and in bad weather. USIS 95
radar intelligence (RADINT) (DoD) Intelligence derived from data collected by radar. JPUB 1-02
radar intelligence item A feature which is radar significant but which cannot be identified exactly at the moment of its appearance as homogeneous. HDBK-850
radar intelligence map (RIM) An intermediate element in the process of light-optical radar simulation and in the production of analytical predictions. HDBK-850
radar map A map produced through the application of radar techniques. HDBK-850
radar photography A combination of the photographic process and radar techniques. Electrical impulses are sent out in predetermined directions and the reflected or returned rays are utilized to present images on cathode-ray tubes. Photographs are then taken of the information displayed on the tubes. HDBK-850
radar prediction categories In the broadest sense, radar prediction is separated into two major categories, experience prediction and analytical prediction. HDBK-850
radar prediction formats Radar predictions appear in a wide variety of formats, generally indicative of intended application. The four most common formats are: spot predictions; strip predictions; radar intelligence maps (RIM); and Series 200 Air Target Charts. HDBK-850
radar prediction types Each major radar prediction category is divided into three types of predictions: single heading predictions; omnidirectional predictions; and omnigain predictions. HDBK-850
radar reconnaissance (JCS) Reconnaissance by means of radar to obtain information, on enemy activity and to determine the nature of terrain. HDBK-850
radar reflectivity plate A scaled, three-dimensional model of a target area constructed of radar reflective materials on a transparent plastic plate, used in a radar trainer to simulate the radar returns of that area. Also called radar simulation plate; radar trainer plate. HDBK-850
radar reflector A device capable of or intended for reflecting radar signals. HDBK-850
radar return analysis Those items of the radar significance analysis code (RSAC), the special area (SA) information, and the radar significant powerline (RSPL) information which has been developed from an analysis of cartographic, photographic, and intelligence sources. HDBK-850
radar return code (RRC) An omnidirectional radar prediction based on the decibel radar prediction system and depicted in a color code on certain air target charts. HDBK-850
Radar Satellite (RADARSAT) RADARSAT is a Canada Centre for Remote Sensing (CCRS) satellite launched by Canada on November 4, 1995. It carries a C-band Synthetic Aperature Radar (SAR), HH polarization, and incidence angles spanning (20 - 60) selectable in a variety of modes. RADARSAT 2 is scheduled for launch in 2001. CCRS Glossary
radar shadow A condition in which radar signals do not reach a region because of an intervening obstruction. HDBK-850
radar significance analysis code (RSAC) The unique radar intensity categories of built-up areas and other radar reflective objects and structures based on surface material/height factors, and depicted by a system of color coding. HDBK-850
radar significant power line (RSPL) A power transmission line which, because of its unique physical characteristics and/or voltage capacity, is known to possess radar reflective qualities, and is therefore distinctively displayed on a target graphic. HDBK-850
radar simulation plate See radar reflectivity plate. HDBK-850
radar target An object which reflects a sufficient amount of a radar signal to produce an echo signal on the radar screen. HDBK-850
radar trainer plate See radar reflectivity plate. HDBK-850
radar, synthetic aperture See Synthetic Aperture Radar (SAR) HDBK-850
radargrammetry That branch of photogrammetry which utilizes radar images. HDBK-850
radarscope overlays (JCS) Transparent overlays for placing on the radarscope for comparison and identification of radar returns. HDBK-850
radarscope photography (JCS) A film record of the returns shown by a radar screen. HDBK-850
radial (photogrammetry) A line or direction from the radial center to any point on a photograph. The radial center is assumed to be the principal point, unless otherwise designated (e.g., nadir radial). See also isoradial; nadir radial; principal-point radial. HDBK-850
radial assumption In an aerial photograph containing both tilt displacement and relief displacement, neither the nadir point nor the isocenter is the theoretically correct radial center. The photographic nadir point should be used as the radial center if relief is the major consideration and the isocenter should be used if tilt is the major consideration. HDBK-850
radial center The selected point on a photograph from which radials (directions) to various image points are drawn or measured; that is, the origin of radials. The radial center is either the principal point, the nadir point, the isocenter, or a substitute center. Also called center of radiation; center point. HDBK-850
radial distortion Linear displacement of image points radially to or from the center of the image field, caused by the fact that objects at different angular distances from the lens axis undergo different magnifications. HDBK-850
radial line (surveying) A radius line of a circular curve to a designated point in the curve; if the line is extended beyond the convex side of the curve, it is a prolongation of the radial line. HDBK-850
radial line intersection That point at which two or more radial lines cross or intersect. HDBK-850
radial line plotter See radial plotter. HDBK-850
radial plot See radial triangulation. HDBK-850
radial plotter A device whereby two overlapping photographs are viewed stereoscopically, and the planimetric details in their common area can then be transferred to a map or base sheet through a mechanical linkage utilizing the radial line principle. Also called radial line plotter. HDBK-850
radial secator See templet cutter. HDBK-850
radial triangulation The aerotriangulation procedure, either graphical or analytical, in which directions from the radial center, or approximate radial center, of each overlapping photograph are used for horizontal control extension by the successive intersection and resection of these direction lines. A radial triangulation also is correctly called a radial plot or a minor control plot. If made by analytical methods, it is called an analytical radial triangulation. A radial triangulation is assumed to be graphical unless prefixed by the word analytical. It is also assumed to be based on the principal point unless prefixed by definitive terms such as isocenter or nadir point. HDBK-850
radiance The amount of electromagnetic energy given off by an object. USIS 95
radiant energy The energy of any type of electromagnetic radiation. See also radiation, definition 2. HDBK-850
radiation 1. (surveying) The process of locating points by a knowledge of their direction and distance from a known point. The directions may be azimuths or bearings read from a theodolite or graphical directions determined by alidade and planetable. The distances may be taped or measured by stadia. 2. The process by which electromagnetic energy is propagated through free space by virtue of joint undulatory variations in the electric and magnetic fields in space. HDBK-850
radio acoustic ranging A means of determining distance by a combination of radio and sound; the radio being used to determine the instant of transmission or reception of the sound, and the distance being determined by the time of transit of sound, usually in water. HDBK-850
radio beacon (JCS) A radio transmitter which emits a distinctive, or characteristic, signal used for the determination of bearings, courses, or location. HDBK-850
radio direction finding (JCS) Radio location in which only the direction of a station is determined by means of its emissions. HDBK-850
radio facility chart See enroute chart. HDBK-850
radio fix (JCS) The location of a ship or aircraft by determining the direction of radio signals coming to the ship or aircraft from two or more sending stations, the locations of which are known. HDBK-850
radio interferometer An interferometer operating at radio frequencies; used in radio astronomy and in satellite tracking. HDBK-850
radio navigation (JCS) Radio location intended for the determination of position or direction or for obstruction warning in navigation. HDBK-850
radio range findings (JCS) Radio location in which the distance of an object is determined by means of its radio emissions, whether independent, reflected or retransmitted on the same or other wavelength. HDBK-850
radio range station (JCS) A radio navigation land station in the aeronautical radio navigation service providing radio equisignal zones. In certain instances a radio range station may be placed on board a ship. HDBK-850
radiometer An instrument for quantitatively measuring the intensity of electromagnetic radiation in some band of wavelengths in any part of the electromagnetic spectrum. Usually used with a modifier, such as an infrared radiometer or a microwave radiometer. CCRS Glossary
radiometric adjustment The refinement of radiometric values of an image based on the results of a calibration. OGC RFI
radiometric camera calibration The calibration of a camera for spectral recording characteristics. HDBK-850
radiometric linearity The gray levels are in linear proportion to the light intensities within a color band. HDBK-850
radiometric nonlinearity The analog to digital conversion system that provides signal to noise (S/N) ratios of the sensors, where the S/N is calculated by the differ'nce of the sensor's average dark signal value divided by the root mean square dark noise value. Intermediate intensities will be linear representations from average white reference to the average dark reference. Intermediate intensities will be represented using a linear tonal transfer curve for each color channel. Error introduced during the digitization process which causes the gray scale values for a color component (RGB) to not be in linear proportion to the source intensities for that component. HDBK-850
radius vector The line (distance) and direction connecting the origin with the point whose position is being defined. See also polar coordinates. HDBK-850
random error Random errors are those not classified as blunders, systematic errors, or periodic errors. They are numerous, individually small, and each is as likely to be positive as negative. Also called accidental error; casual error. HDBK-850
random line A trial line, directed as closely as possible toward a fixed terminal point which is invisible from the initial point. The error of closure permits the computation of a correction to the initial azimuth of the random line; it also permits the computation of offsets from the random line to establish points on the true line. HDBK-850
random microlenticular (RML) screen A high density halftone screen with no specific screen angle or pattern used to produce high resolution printing from continuous tone images. HDBK-850
random traverse A survey traverse run from one survey station to another station which cannot be seen from the first station in order to determine their relative positions. HDBK-850
range 1. (JCS) The distance between any given point and an object or target. 2. The difference between the maximum and minimum of a given set of quantities. See also distance. 3. Two or more objects in line. Such objects are said to be in range. 4. Any series of contiguous townships situated north and south of each other; also sections similarly situated within a township. 5. The well-defined lines or courses whose positions are known and are used in determining soundings in a hydrographic survey. HDBK-850
range finder An instrument, using the parallax principle, for finding the distance from a place of observation to points at which no instruments are placed. HDBK-850
range line A boundary of a township surveyed in a north-south direction. See also township lines. HDBK-850
range marker (JCS) A single calibration blip fed on to the time base of a radial display. The rotation of the time base shows the single blips as a circle on the plan position indicator scope. It may be used to measure range. HDBK-850
Range Only Correlation System (ROCS) An all-weather terminal guidance system that uses ranging information to determine its position by comparing two radar images. The images are taken 90 apart and compared with a reference (or prediction) of contrast edge information (bright spots) in the range return signal. The checkpoint is a geographic reference location, selected prior to the mission, by which the vehicle can determine course correction. HDBK-850
range pile Any pile serving as a guide for marine surveying. HDBK-850
range pole See range rod. HDBK-850
range rate data Information gathered by an instrument that measures the rate of change in the distance (range) to a moving object. HDBK-850
range resolution (JCS) The ability of the radar equipment to separate two reflecting objects on a similar bearing, but at different ranges from the antenna. The ability is determined primarily by the pulse length in use. HDBK-850
range rod A slender wood or metal rod, 6 to 8 feet long, with a pointed metal shoe, usually painted in contrasting colors (red and white), alternately, at 1-foot intervals. It is frequently used as a sighting signal at the ends of traverse courses. Also called line rod; lining pole; range pole; ranging pole; sight rod. HDBK-850
range signal A buoy, rod, flag, or other similar object used to mark and identify range points when taking soundings during a hydrographic survey. HDBK-850
ranging data Information gathered by an instrument that measures the distance (range) to the object in question. HDBK-850
ranging pole See range rod. HDBK-850
ranging-in See wiggling-in. HDBK-850
raster 1. Pattern of horizontal, parallel lines of varying intensity forming an image (usually) on a cathode ray tube screen. 2. A regular grid of cells covering an area. HDBK-850
raster Consisting of one or more regular 2-dimensional arrays of pixels or grid cells covering an area. ISO/TC 211
raster Originally, a scan line in an electronic display such as a television or computer monitor. In geoprocessing, raster refers to digital geographic databases built from grid cells in a matrix. A raster display builds an image from pixels, small square picture elements of coarse or fine resolution. A raster database maintains a similar "picture" of reality in which each cell records some sort of information averaged over the cell's area. The size of the cell may again be coarse or fine, ranging from centimeters to kilometers. Many satellites, like LANDSAT and SPOT, transmit raster images of the Earth's surface. Reflectance at a certain wavelength is measured for each cell in an image. OpenGIS Guide
raster band A 2-dimensional geometric primitive which is a regular tessellation of a limited part of the base surface. ISO/TC 211
raster data Data represented in a regular spatial array. ISO/TC 211
raster data structure A method of representing MC&G data characterized by a matrix of evenly spaced rows and columns of data points. These data points (called "pixels" in image and scanned map data) typically represent some value at that point, while the position within the columns and rows determines the geographic position. Raster data structures are typically used to record scanned maps and charts (MC&G graphic data), image data, or gridded data. HDBK-850
raster display A graphics monitor, such as a cathode ray tube (CRT) or television monitor, that generates dots or pixels, line by line, on the screen to display an image. Compared to a vector display device, that draws the lines, not images on the screen. USIS 95
raster format See raster data structure. HDBK-850
raster lines The lines of scan of the CRT beam across the CRT face. See also raster. HDBK-850
raster map map data based on a raster data model ISO/TC 211
raster map product (RMP) A generic term for raster scanned map images not found to be in accordance with the NIMA ADRG Specification or production program; excludes USATEC's ADRG-S (raster separates). HDBK-850
raster object An object of one or more layers that are each raster in form. NOTE - Corresponding grid cells and/or pixels between layers are congruent and registered. ISO/TC 211
Raster Product Standard(s) (RPS) A suite of user system oriented standards encompassing raster data structure digitizing conventions, storage formats and tiling schemes. HDBK-850
raster to vector The process of converting an image made up of cells into one described by lines and polygons. HDBK-850
rate station See drift station. HDBK-850
ratio print A print in which the scale has been changed from that of the negative by photographic enlargement or reduction. HDBK-850
ratiograph See ratiometer. HDBK-850
ratiometer An instrument used to help solve the mathematical relationship of a photograph to a mosaic. It determines scale ratios from which, through mathematical formulas, a rectified print can be made on a properly calibrated rectifying printer. HDBK-850
rational horizon See celestial horizon. HDBK-850
rationalization method A technique of relative orientation which takes into consideration the limiting factors of the equipment being used, the nature and variations of tilt and crab angles at successive camera stations, and providing approximate projector adjustments based on these data. HDBK-850
ray of light The geometrical concept of a single element of light propagated in a straight line and of infinitesimal cross section; used in analytically tracing the path of light through an optical system. See also beam of light. HDBK-850
ray tracing (optics) A trigonometric calculation of the path of a light ray through an optical system. HDBK-850
Raydist The trade name of an electronic distance measuring system. A nonline-of-sight system capable of simultaneous multiparty, range-range operation; it gives continuous range information from two base stations operating simultaneously with one or more aircraft and surface vessels. HDBK-850
Ready for Distribution (R4D) A term referring to printed MC&G products ready to be distributed to the customer. HDBK-850
Ready for Reproduction (R4R) A term referring to reproduction material ready to be printed. HDBK-850
real image An image actually produced and capable of being shown on a surface, as in a camera. HDBK-850
real-time Real-time is a mode of operation. Real-time systems require events, data, and information to be available in time for the system to perform its required course of action. Real-time operation is characterized by scheduled event, data, and information meeting their acceptable arrival times. [OS-JTF]
-or-
Absence of delay, except for the time required for transmission. [DoD HCI Style Guide]
JTA 2.0
real-time control system Systems capable of responding to external events with negligible delays. (DoD HCI Style Guide) JTA 2.0
realtime math model A set of equations that defines image coordinates as functions of three-dimensional object coordinates for a region of imagery. HDBK-850
real-time systems Systems which provide a deterministic response to asynchronous inputs. (OS-JTF) JTA 2.0
rear element See lens element. HDBK-850
rear nodal point See nodal point. HDBK-850
recall (digital) A procedure which restores the previous entry. HDBK-850
recast To change a map from one horizontal datum to another by appropriately changing the geographic values of the map graticule. HDBK-850
receiver 1. (pendulum) A heavy-cast metal box within which the pendulum is suspended and some auxiliary equipment placed when making observations for the intensity of gravity. 2. (satellite surveying) The equipment necessary to receive signals broadcast from the Navy Navigation Satellite System, including an antenna, preamplifier, processor, oscillator, output device, and power system. HDBK-850
reciprocal bearing See back bearing, definition 1. HDBK-850
reciprocal leveling Trigonometric leveling wherein vertical angles have been observed at both ends of the line to eliminate errors. HDBK-850
reciprocal observations Observations taken backward and forward such as vertical angles at both termini of a line for trigonometric leveling. HDBK-850
reciprocal vertical angle A vertical angle measured over a line at both ends in trigonometric leveling to eliminate (at least partly) the effects of curvature and refraction. Reciprocal observations must be made as simultaneously as practicable to obviate error caused by changing refractive conditions. HDBK-850
reclassify (digital) A procedure to change the classification of existing data. HDBK-850
recognition In photointerpretation, the act of discovering the true identity of an object. HDBK-850
recompilation The process of producing a map or chart that is essentially a new item and which replaces a previously published item. Normally, recompilation of a map or chart involves significant change to the horizontal position of features, revision of vertical values, improvement in planimetric or navigational data, or any combination of these factors. HDBK-850
RECON 2 Message A message from an airborne collection unit that identifies the planned collection for a particular reconnaissance mission. USIS 95
RECON 3 Message A message from an airborne collection unit that identifies the actual collection accomplished for a particular reconnaissance mission. USIS 95
reconnaissance (JCS) A mission undertaken to obtain, by visual observation or other detection methods, information about the activities and resources of an enemy or potential enemy; or to secure data concerning the meteorological, hydrographic, or geographic characteristics of a particular area. See also aerial reconnaissance; hydrographic reconnaissance; radar reconnaissance; triangulation reconnaissance. JPUB 1-02
Reconnaissance Exploitation Report (RECCEXREP) The proforma used to report the results of a tactical air reconnaissance mission. Whenever possible the report should include the interpretation of sensor imagery. A DoD reporting product that provides abbreviated visual imagery exploitation reporting mainly from tactical imagery collection tasked at the local command level. The RECCEXREP format is installation/event oriented and may contain theater-unique data elements. RECCEXREP reports may be issued in response to five imagery collection mission types: Tactical Air Reconnaissance (land), Tactical Air Reconnaissance (maritime), Armed Reconnaissance (maritime), DoD theater, and national airborne reconnaissance missions. USIS 95
Reconnaissance Exploitation Report (RECCEXREP) Message An electronically transmitted Department of Defense (DoD) reporting product that contains a single, modified direct support imagery interpretation report (IIR) for the purpose of disseminating this report to tactical military forces. USIS 2-1.1
reconnaissance imagery materials Reconnaissance imagery materials are all data associated with reconnaissance imagery (i.e., collection, intelligence, and map products) and imagery technical data. The term "material" is all inclusive and applies to such formats as briefings, target materials, memorandums, reports, and other publications associated with reconnaissance imagery. USIS 95
reconnaissance map The plotted results of a reconnaissance survey and data obtained from other sources. HDBK-850
reconnaissance photography (JCS) Photography taken to obtain information on the results of bombing, or on enemy movements, concentrations, activities and forces. The primary purposes do not include making maps, charts, or mosaics. HDBK-850
reconnaissance sketch A drawing which resembles a reconnaissance map but is lacking in some map element. HDBK-850
reconnaissance survey A preliminary survey, usually executed rapidly and at relatively low cost. The information obtained is recorded, to some extent, in the form of a reconnaissance map or sketch. HDBK-850
reconstructed imagery Imagery on film derived from processed digital image data by means of film printer. HDBK-850
recording statoscope A statoscope equipped with a recording camera whose shutter is synchronized with that of the aerial camera and the image of the statoscope is recorded on each individual frame. HDBK-850
recover (surveying) To visit a survey station, identify its mark as authentic and in its original location, and verify or revise its description. The term is usually modified to indicate the type or nature of the recovery, such as recovered bench mark, or a recovered triangulation station. HDBK-850
recovered control See recover. HDBK-850
recovery of station See recover. HDBK-850
rectagraver A scribing instrument which rests on the scribing surface during the operation and only the cutter arm moves to scribe each symbol. HDBK-850
rectangular chart A chart on the rectangular projection. HDBK-850
rectangular coordinate plotter See coordinatograph. HDBK-850
rectangular coordinates Coordinates on any system in which the axes of reference intersect at right angles. See also Cartesian coordinates. HDBK-850
rectangular map projection A cylindrical map projection with uniform spacing of the parallels. HDBK-850
rectangular polyconic map projection A modified polyconic map projection having a line representing a standard parallel divided to exact scale, through whose division points pass the lines representing the geographic meridians, intersecting the lines which represent the geographic parallels in right angles. HDBK-850
rectangular space coordinates The perpendicular distances of a point from places defined by each pair of a set of three axes which are mutually perpendicular to each other at a common point of origin. In photogrammetry, space coordinates are also called survey coordinates, and are the x-coordinates and y-coordinates which define the horizontal position of a point on a ground system, and the z-coordinate, which is the elevation of the point with reference to the ground system. Also called air coordinates. HDBK-850
rectangular surveys A system of surveys in which an area is divided by a base line intersected at right angles by a principal meridian, the intersection termed the initial point from which the partitions are subdivided into equal size townships containing 36 sections of land each. HDBK-850
rectification (JCS) In photogrammetry, the process of projecting a tilted or oblique photograph onto a horizontal reference plane. [Although the process is applied principally to aerial photographs, it may also be applied to the correction of map deformation.] See also analytical orientation; empirical orientation; graphical rectification; multiple-stage rectification; optical rectification; paper-strip method; point-matching method; transformation. HDBK-850
rectification The geometric adjustment of image pixels to remove distortions caused by the imaging sensor and the geometry of the sensor to the ground. For the removal of terrain relief displacement see orthorecification. OGC RFI
rectified altitude See apparent altitude. HDBK-850
rectified print A photograph in which tilt displacement has been removed from the original negative, and which has been brought to a desired scale. HDBK-850
rectifier A specially designed projection printer whose geometry is variable in order to eliminate tilt from an aerial negative. There are two basic types; those in which the optical axis of the rectifier lens is the common reference or base direction of the instrument, and those in which the line between the principle point of the negative and the rectifier lens is the common reference. Also called automatic rectifier; nonautomatic rectifier; nontilting- lens rectifier; nontilting-negative- plane rectifier; rectifying camera; tilting-lens rectifier. See also autofocus rectifier; transforming printer. HDBK-850
rectifying camera See rectifier. HDBK-850
rectifying latitude The latitude on a sphere such that a great circle on it has the same length as a meridian on the spheroid and such that all lengths along a meridian from the Equator are exactly equal to the corresponding lengths on the spheroid. Rectifying latitude is an auxiliary latitude used in problems of geodesy and cartography. HDBK-850
rectifying printer See rectifier. HDBK-850
rectilinear coordinates See rectangular coordinates. HDBK-850
rectoblique plotter See angulator. HDBK-850
rectoplanigraph An instrument utilizing a vertical photograph mounted in a vertical position, and used in the preparation of planimetric maps. HDBK-850
red light readable map A map printed with special inks which can be read under conditions requiring special lighting; e.g., in a tank or aircraft during nighttime operations. HDBK-850
red magnetism The magnetism of the north-seeking end of a freely suspended magnet. This is the magn'tism of the Earth's south magnetic pole. See also blue magnetism. HDBK-850
reduced gravity Observed gravity that has been reduced to the geoid or to some other reference surface by one of the gravity reductions. HDBK-850
reduced latitude See parametric latitude. HDBK-850
reduced resolution data set (RRDS) Original, high-resolution imagery is useful for many applications (especially close-up displays), but for overall displays there may be too much data to process. For example, if the raw image consists of 16K X 16K pixels, it is impossible to fit this much data into the cathode ray tube refresh memory at once to build an overview display. Therefore, RRDSs are created (as a preprocessing step) and are used as input by overview displays whenever the original high-resolution data are impossible to use. An original 16K X 16K (=256 megabytes) may be reduced to 1K X 1K (=1 megabyte) for overview purposes. USIS 95
reduction factor See scale of reproduction. HDBK-850
reduction printer See diapositive printer. HDBK-850
reduction to ellipsoid The correction subtracted from or added to the measured horizontal Iength of a line at average topographic elevation to reduce it to the corresponding length on the pertinent ellipsoid. The height used in this reduction will differ by the amount of the geoid height from the height used in reduction to sea level. HDBK-850
reduction to sea level A reduction applied to a measured horizontal length on the Earth's surface to reduce it to the surface of the local sea level datum. HDBK-850
reduction to the meridian The process of applying a correction to an altitude observed when a body is near the celestial meridian of the observer, to find the altitude at meridian transit. The altitude at the time of such an observation is called an exmeridian altitude. HDBK-850
reduction-to-center 1. The amount which must be applied to a direction observed at an eccentric station or to an eccentric signal, to reduce such direction to what it would be if there were no such eccentricity. 2. (astronomy) One of the values used in finding the equation of time. HDBK-850
Redundant Array of Independent Disks (RAID) A series of disk drives interconnected in parallel to act as one. Multimedia
reference date The date to which an indirect spatial reference system refers. CEN/TC 287
reference datum A general term applied to any datum, plane, or surface used as a reference or base from which other quantities can be measured. HDBK-850
reference datum (UCDM Entity: "REFERENCE-DATUM") A collection of geometric elements used as a reference. USIGS/CDM-A
reference direction A direction used as a basis for comparison of other directions. HDBK-850
reference ellipsoid See reference spheroid. HDBK-850
reference frame See coordinates. HDBK-850
reference grid See grid. HDBK-850
Reference Implementation {DII COE} The set of software and hardware components that implement a COE. The reference implementation of a COE may change over time to take advantage of new technologies or to fix problem reports, but the principles governing the COE remain unchanged. A COE is incomplete without a reference implementation because it is the reference implementation that is most responsible for ensuring interoperability. The DII COE is an example of a reference implementation. DII COE IRTS
reference level See datum level. HDBK-850
reference line Any line which can serve as a reference or base for the measurement of other quantities. Also called datum line. HDBK-850
reference mark A permanent supplementary mark close to a survey station to which it is related by an accurately measured distance and direction, and/or a difference in elevation. HDBK-850
reference meridian See local meridian. HDBK-850
reference model A structured collection of concepts and their relationships that scope a subject and enable the partitioning of the relationships into topics relevant to the overall subject and that can be expressed by a common means of description. IEEE P1003.0
reference model A reference model is a generally accepted abstract representation that allows users to focus on establishing definitions, building common understandings and identifying issues for resolution. Reference models provide a mechanism for identifying key issues associated with portability, scalability, and interoperability. (TRI-SERVICE Open Systems Architecture Working Group) JTA 2.0
reference monument An iron post or rock cap accessory used where the point for a corner monument is such that, for practical purposes, a permanent corner monument cannot be established, or if monumented, a full complement of bearing trees or bearing objects are not obtainable. HDBK-850
reference plane See datum level. HDBK-850
reference point See datum point. HDBK-850
reference point In an architecture, an interaction point designated for selection as a conformance point. The conformance point appears in a specification which is compliant with that architecture. RM-ODP
reference signal In telemetry, the signal against which data carrying signals are compared to measure differences in time, phase, frequency, or other values or quantities. HDBK-850
reference spheroid A theoretical figure whose dimensions closely approach the dimensions of the geoid; the exact dimensions are determined by various considerations of the se'tion of the Earth's surface concerned. Also called reference ellipsoid; spheroid of reference. See also World Geodetic System. HDBK-850
reference station A place where tide or tidal current constants have been determined from observations, and which are used as a standard for the comparison of simultaneous observations at a subordinate station. Also, a place for which independent daily predictions are obtained for other locations by means of differences or factors. Also called standard port; standard station. HDBK-850
referencing The process of measuring the horizontal distances and directions from a survey station to nearby landmarks, reference marks, and other objects which can be used in the recovery of the station. HDBK-850
referential integrity The property ensuring that an object reference that exists in the state associated with an object reliably identifies a single object. CORBA 2.2
refinement The process of transforming a specification into a more detailed specification. Specifications and their refinements typically do not co-exist in the same system description. RM-ODP
reflected radiance The amount of electromagnetic energy reflected from a target scene, normally from the sun. USIS 95
reflected ray A ray extending outward from a point of reflection. HDBK-850
reflecting prism A prism that deviates a light beam by internal reflection. Practically all prisms used in photogrammetric instruments are of this type. HDBK-850
reflecting projector An instrument which is used to project the image of photographs, maps, or other graphics onto a copying table. The scale of the projected image can be varied by raising or lowering the projector or, in some models, the copy board. These latter models also allow the tilting of the copy board in x- and y-directions in order to compensate for tip and tilt distortion in aerial photographs. HDBK-850
reflection The return or change in the direction of travel of particles or radiant energy which impinges on a surface but does not enter the substance providing the reflecting surface. See also diffraction; diffuse reflection; refraction; specular reflection. HDBK-850
reflector constant The amount that a distance measurement must be reduced when using glass reflectors because the velocity of light is slower in glass than it is in air. The constant will also include the distance difference between the reflector housing plumbing point and the effective reflecting plane of the prism. HDBK-850
reflight Another flight over the same course to secure photographs to fill in for those missing or defective. HDBK-850
refracted ray A ray extending onward from the point of refraction. HDBK-850
refracting prism A prism that deviates a beam of light by refraction. The angular deviation is a function of the wavelength of light; therefore, if the beam is composed of white light, the prism will spread the beam into a spectrum. Refracting prisms can be used in optical instruments only for small deviations. See also wedge. HDBK-850
refraction The change in direction of motion of a ray of radiant energy as it passes obliquely from one medium into another in which the speed of propagation is different. See also angle of incidence; angle of refraction; astronomic refraction; atmospheric refraction; coastal refraction; coefficient of refraction; electronic refraction; horizontal refraction; lateral refraction; mean refraction; refracted ray; refraction angle; refraction line; Snell's law of refraction; terrestrial refraction. HDBK-850
refraction angle That portion of an observed zenith distance, which is due to the effect of atmospheric refraction. HDBK-850
refraction displacement Displacement of images radially outward from the photograph nadir because of atmospheric refraction. It is assumed that the refraction is symmetrical about the nadir direction. HDBK-850
refraction line A line of sight to a survey signal which becomes visible only by the effect of atmospheric refraction. HDBK-850
regional gradient See regional gravity. HDBK-850
regional gravity In gravity prospecting, contributions to the observed anomalies due to density irregularities at much greater depths than those of the possible structures, the location of which was the purpose of the survey. Also called regional gradient. HDBK-850
register (JCS) The correct position of one component of a composite map image in relation to the other components, at each stage of production. HDBK-850
register hole punch See prepunch register system. HDBK-850
register marks (JCS) Designated marks, such as small crosses, circles, or other patterns applied to original copy prior to reproduction to facilitate registration of plates and to indicate the relative positions of successive impressions. Also called corner marks; corner ticks; register ticks; registration ticks; ticks. HDBK-850
register studs See prepunch register system. HDBK-850
register ticks See register marks. HDBK-850
register trials The test runs necessary to obtain the proper combination of the degree of partial vacuum and the length of the heating cycle required for individual models in forming a plastic relief map. HDBK-850
registration ticks See register marks. HDBK-850
regression of the nodes Precessional motion in a direction opposite to the direction of revolution of a set of nodes. See also precession. HDBK-850
regular error See systematic error. HDBK-850
Relational Analysis of Internetted Linkages System System for analyzing and determining the importance of nodes within a specified communications system. USIS 95
relational data base A data base that consists of at least one table, which, in turn, is made up of rows and columns. Tables in the data base are related to one another through the value in at least one column that is common to two or more tables. HDBK-850
relational database Stores data in such a way that it can be added to, and used independently of, all other data stored in the database. Users can query a relational database without knowing how the information has been organized. Although relational databases have the advantages of ease-of-use and analytical flexibility, their weakness can be slower retrieval speed. SQL (structured query language) is an interface to a relational database. OpenGIS Guide
relationship, connection An association or connection between entities in which each instance of the parent entity is associated with zero, one, or more instances of the child entity, and each instance of the child entity is associated with exactly one instance of the parent entity. USIGS/CDM-A
relationship, non-specific An association between two entities in which each instance of the first entity may be associated with zero, one, or many instances of the second entity and each instance of the second entity is associated with zero, one, or many instances of the first entity. Also referred to as a "many-to-many relationship". USIGS/CDM-A
relative accuracy 1. (general) An evaluation of the random errors in determining the positional orientation (e.g., distance, azimuth) of one point or feature with respect to another. 2. (chart, feature to graticule) An evaluation of the random errors in chart features with respect to the graticule excluding any error in the graticule or the datum defined by the graticule. 3. (chart, feature to feature) An accuracy evaluation based on random errors in determining the positional accuracy of one point feature with respect to another feature. HDBK-850
relative aperture (JCS) The ratio of the equivalent focal length to the diameter of the entrance pupil of photographic lens, expressed as f:4.5, etc. Also called aperture ratio; aperture stop; diaphragm stop; f-number; lens speed; speed of lens; stop; stop numbers. HDBK-850
relative coordinate system Any coordinate system which is moving with respect to an inertial coordinate system. HDBK-850
relative deflection See astrogeodetic deflection. HDBK-850
relative direction Horizontal direction expressed as angular distance from a heading. HDBK-850
relative distance Distance relative to a specified reference point, usually one in motion. HDBK-850
relative error of closure The value obtained by dividing the total error of closure by the total length of the traverse, commonly expressed by a fraction having a numerator equal to unity, e.g., 1/1,540. It is used for determining the degree of accuracy of a survey. HDBK-850
relative gravity Gravity determined from gravity difference measurements (e.g., gravimeter, relative pendulum) between the observer and a reference station. The value obtained is relative with respect to the reference station. HDBK-850
relative motion See apparent motion. HDBK-850
relative movement Motion of one object or body relative to another. The expression is usually used when describing relative movements other than that of a celestial body. See also apparent motion; direction of relative movement. HDBK-850
relative orientation The reconstruction (analytically or in a photogrammetric instrument) of the same geometric conditions between a pair of photographs that existed when the photographs were taken. In the instrument, this is achieved by a systematic procedure of rotational and translational movements of the projectors. Also called clearing y-parallax. See also absolute orientation; vertical deformation. HDBK-850
relative pendulum A device for measuring relative gravity through the difference in the period of a pendulum at two stations. HDBK-850
relative position The location of a point or feature with respect to other points or features, either fixed or moving. HDBK-850
relative relief The relation of the altitudes of the highest and lowest points of land in any area. The difference between the highest and lowest points is the amplitude of relative relief. Various types of maps have been devised to show this, usually depending on gridding the area on a map, finding a value for the amplitude in each grid square, and producing an isopleth or dot map to depict the distribution of these values. HDBK-850
relative setting In tilt analysis of oblique photography, the dihedral angle between the two planes passing through the principal point of the opposite obliques, the principal point of the vertical photograph, and the common exposure station. This angle is measured on the vertical photograph as the angle between the two isolines, or as the deflection angle between the perpendiculars from the principal point of the vertical photograph to the two isolines. HDBK-850
relative swing In the tilt analysis of oblique photographs, the angle of rotation of the oblique camera about its own axis with respect to the plane of the vertical photograph, measured on the oblique photograph by the angle between the isoline and a line joining the fore and aft fiducial marks. HDBK-850
relative tilt The angular relationship between two overlapping vertical photographs with no reference to an established datum. HDBK-850
releasability code letter A code letter prefix to the chart identification number which limits the releasability of a particular chart to specific users. HDBK-850
release marking (A&D LDM Entity: "RELEASE-MARKING") A mark identifying a country or country grouping to which data is authorized for release. A&D LDM
reliability The metaquality element describing the likelihood that a sample of a geographic subset used for quality assessment is representative of the whole subset. For quality measures, reliability may be reported by statistical indicators. Otherwise, reliability will be reported as an explanatory text. CEN/TC 287
reliability diagram A diagram included on some MC&G products depicting horizontal and vertical accuracies and date(s) of information HDBK-850
relief (JCS) Inequalities of elevation and the configuration of land features on the surface of the Earth which may be represented on maps or charts by contours, hypsometric tints, shading, spot elevations, or hachures. HDBK-850
relief displacement Displacement radial from the nadir point of a photograph caused by differences in elevation of the corresponding ground objects. Also called height displacement; relief distortion. HDBK-850
relief distortion See relief displace-ment. HDBK-850
relief model A general category which denotes any three-dimensional representation of an object or geographic area, modeled in any size or medium. See also plastic relief map; terrain model. HDBK-850
relief stretching See hyperstereoscopy. HDBK-850
Relocatable Army Processors for Intelligence Data (RAPID)-Europe The U.S. Army Europe intelligence automated data processing program. It includes a Modular Architecture for the Exchange of Intelligence (MAXI) for message handling, and a Collection Management System Tool (CMST) for collection management, and the Integrated Data Base. USIS 95
Relocatable Target Adaptive Planning System A system devised by DIA to identify likely operational areas for relocatable targets. USIS 95
Relocatable Target Assessment Data (RTAD) NIMA digital data sets of attributed and nonsymbolized feature information segregated into thematic files portraying roads, railroads, vegetation, surface drainage, and limited surface materials which can be combined into three separate levels of data. All three levels use standard DTED Level 1 to determine elevation, slope, and intervisibility and are intended to be used with multispectral or electro-optical image products. RTAD is used to assess potential target locations. HDBK-850
Relocation Transparency A distribution transparency which masks relocation of an interface from other interfaces bound to it. RM-ODP
remapping An image processing technique for enhancing gray-tone levels of particular features of interest within one or more radar images. The technique is similar to histogram stretching. USIS 95
Remote Install {DII COE} The ability to electronically install segments from a local site (such as the DISA Operational Support Facility) to a remote site (such as USACOM). In a "push" mode, the local site initiates and controls the segment installation. In a "pull" mode, the remote site initiates and controls the segment installation. DII COE IRTS
Remote Procedure Call (RPC) An API [aplication program interface]for remote execution of detailed functions. OpenGIS Guide
remote sensing (R/S) Group of techniques for collecting image or other forms of data about an object from measurements made at a distance from the object, and the processing and analysis of the data. CCRS Glossary
remote station See slave station. HDBK-850
remotely piloted vehicle An unmanned air vehicle capable of being controlled by a person from a distant location through a communications link. It is normally designed to be recoverable. See also Unmanned Aerial Vehicle (UAV). USIS 95
rendering The manipulation of visual objects in real-time. Multimedia
repeat access orbit The ground track is repeated exactly on a recurring basis. USIS 95
repeatability A measure of the variation in the accuracy of an instrument when tests are made over the same line(s) at different times of the year, with different operators, and with different but equivalent instruments, all using the same procedures. See also external error. HDBK-850
repeating instrument See repeating theodolite. HDBK-850
repeating theodolite A theodolite so designed that successive measures of an angle may be accumulated on the graduated circle, and a final reading of the circle made which represents the sum of the repetitions. Also called double-center theodolite; repeating instrument. HDBK-850
repetition of angles The accumulation of a series of measures of the same angle on the horizontal circle of a repeating theo'olite or surveyor's transit. HDBK-850
replace A procedure to replace all existing occurrences of a specified data element with a new data element. HDBK-850
Replication Transparency A distribution transparency which masks the use of a group of mutually behaviorally compatible objects to support an interface. Replication is often used to enhance performance and availability. RM-ODP
reporting requirement The statement of a need for imagery-derived intelligence that includes the description of the format, the periodicity or due date, and the organization responsible for developing the report. USIS 95
reporting, imagery The process of conveying imagery-derived intelligence from the imagery exploitation center to the consumer within the Intelligence Community. The reporting formats are data base entry, cable (in a variety of formats), hardcopy detailed reports, or graphics. USIS 95
repository {CORBA} See interface repository and implementation repository. CORBA 2.2
representative fraction (RF) (JCS) The scale of a map or chart expressed as a fraction or ratio. [Relates unit distance on the map to distance measured in the same unit on the ground.] Also called fractional scale; natural scale. HDBK-850
representative pattern (cartography) 1. An accurate portrayal of the surface of the Earth in the area being compiled. 2. The selection and portrayal of the most prominent of a dense group of similar features. HDBK-850
reprint The process of using existing reproducible without change to print additional quantities of a product. HDBK-850
reproducible Any copy capable of being used as a master-to-be. May be either a negative or positive transparency. HDBK-850
reproduction 1. The summation of all the processes involved in printing copies from an original drawing. 2. A printed copy of an original drawing made by any of the processes of reproduction. HDBK-850
reproduction material (JCS) Material, generally in the form of positive or negative copies on film or glass for each color plate, from which a map or chart may be reproduced without redrafting. Also called repromat. HDBK-850
reproduction positive mold The positive mold which has been drilled through with vacuum holes, and over which the plastic relief map is formed. HDBK-850
reproduction ratio See scale of reproduction. HDBK-850
reproduction scale The scale at which a map or chart is published or is to be published. Also called publication scale. HDBK-850
repromat See reproduction material. HDBK-850
Repsold base-line measuring apparatus An optical base-line measuring apparatus, composed of a steel bar approximately 4 meters long, whose exact length at any temperature is known, and whose temperature is determined by means of a metallic thermometer composed of the steel measuring bar and a similar bar of zinc, the two being fastened together at their middle points. HDBK-850
repudiation The denial by a message originator or recipient that the message was sent or received. [DISA/D2] DISA CFS
request A client issues a request to cause a service to be performed. A request consists of an operation and zero or more actual parameters. CORBA 2.2
Request for Change (RFC) The formal mechanism to submit changes to a program under development or under configuration management control. USIS 95
Required Looks Per Day (RLPD) The number of imaging operations per day required to satisfy an imaging requirement. The requirement may be a single target or a group of targets, and the RLPD may be computed for a specific geographic area (e.g., a georegion). RLPD is computed by dividing the period by the required number of looks (imaging operations). USIS 95
requirement A need or demand. (DDDS 12451/1 (D)) See also military requirement. C4ISR AF
requirement 1. A condition or capability needed by a user to solve a problem or achieve an objective. 2. A condition or capability that must be met or possessed by a system or system component to satisfy a contract, standard, specification, or other formally imposed document. See also military requirement. S/W Reuse
requirement A statement or expression of need relative to imagery intelligence. This may be an expression of need for the collection, exploitation, production and distribution, and reporting of imagery. In addition, the Imagery Requirements Structure allows users to define conditional tasking rules. See also military requirement. USIS 95
requirement effectivity date The date specified by a user to start image collection. USIS 95
requirements characterization Five determinants are used to differentiate processing and exploitation. Time dominant and non-time-dominant characterize the urgency of a requirement while operational, policy, and baseline characterize the initial use associated with a requirement. USIS 95
Requirements Data Base (RDB) A listing of registered collection requirements. USIS 95
requirements management Encompasses the processes, equipment, and capabilities that create, register, validate, prioritize, send, monitor, and receive the submission of requests for substantive imagery products. USIS 95
Requirements Management System (RMS) A system for the management of theater and national imagery requirements. Automated tools will be provided for users in support of submission of imagery nominations, review, and validation as requirements to be tasked on national or DoD imagery collection, production and distribution, and exploitation resources. USIS 95
resampling (digital mapping) Technique for transforming a raster image to a particular scale and projection. Common resampling techniques include zero-order (nearest-neighbor), first order (bilinear interpolation) and cubic convolution. HDBK-850
rescale An adjustment of values or parameters representing magnitudes or intensity so that the data reflects an aspect more suited to the user. HDBK-850
research and development (R&D) categories {DoD} Several categories or definitions of research and development (R&D) or research, development, test and evaluation (RDT&E) are used throughout the community. For purposes of the Imagery Research and Development Council, R&D or RDT&E categories are as follows; Basic Research (category 6.1), Exploratory Development (category 6.2), Advanced Development (category 6.3a), Demonstration and Validation (category 6.3b), Engineering Development (category 6.4) and Management and Support (category 6.5). These definitions are modified DoD definitions used by the Community Management Staff (Advanced Technology Office) and the OSD Intelligence Program Support Group. In general, fundamental science research activities fall in the 6.1 and 6.2 categories. Advanced research and development generally falls within the 6.2 and 6.3a categories. Development, testing, and evaluation activities generally known as "Development and R&D" fall in the 6.3b, and 6.4 areas. See also acquisition categories {DoD}. USIS 95
Research and Development for Image Understanding Systems (RADIUS) The overall goal of RADIUS is to improve the productivity, timeliness, and quality of image exploitation through image understanding technology development and planning for the insertion of the technology into operational practice. USIS 95
reseau 1. A glass plate on which is etched an accurately ruled grid. Sometimes used as a focal-plane plate to provide a means of calibrating film distortion; used also for calibrating plotting instruments. Also called grid plate. 2. Intersecting orthogonal lines superimposed over photo imagery. HDBK-850
reseau mark A grid system of a standard size in the image plane of a photographic system used for mensuration purposes. USIS 95
resection 1. The graphical or analytical determination of a position, as the intersection of at least three lines of known direction to corresponding points of known position. 2. (surveying) The determination of the horizontal position of a survey station by observed directions from the station to points of known positions. Also, the line drawn through the plotted location of a station to the occupied station. 3. (photogrammetry) The determination of the position and/or attitude of a camera, or the photograph taken with that camera, with respect to the exterior coordinate system. Also called three-point method. See also intersection, definition 2. HDBK-850
resection station A station located by resection methods. HDBK-850
residual A general term denoting a quantity remaining after some other quantity has been subtracted. It occurs in a variety of particular contexts. For example, if the true value of a variable is subtracted from an observed value then the difference may be called a residual; it is also frequently called an error. Similarly, if a mathematical model is fitted to data, the values by which the observations differ from the model values are called residuals. HDBK-850
residual deviation Deviation of a magnetic compass after adjustment or compensation. HDBK-850
residual error The difference between any value of a quantity in a series of observations, corrected for known systematic errors, and the value of the quantity obtained from the combination or adjustment of that series. Frequently used as the difference between an observed value and the mean of all observed values of a statistically valid set. See also error; residual. The latter term is generally used in referring to actual values in a specific computation. HDBK-850
residual gravity In gravity prospecting, the portion of a gravity effect remaining after removal of some type of regional gravity, usually the relatively small or local anomaly components of the total or observed gravity field. HDBK-850
residual parallax Small amounts of y-parallax which may remain in a model after relative orientation is accomplished. HDBK-850
resolution 1. For raster applications, resolution is the number or pixels per unit distance. 2. (JCS) A measurement of the smallest detail which can be distinguished by a sensor system under specific conditions. 3. The minimum distance between two adjacent features, or the minimum size of a feature, which can be detected by a remote sensory system. 4. In gravity or magnetic prospecting, the indication in some measured quantity, such as the vertical component of gravity, of the presence of two or more close but separate disturbing bodies. HDBK-850
resolution The minimum difference between two independently - measured or computed values which can be distinguished by the measurement or analytical method being considered or used. ISO/TC 211
resolution 1. (DoD, NATO) A measurement of the smallest detail that can be distinguished by a sensor system under specific conditions. 2. The measure of the ability of a lens, photographic system to distinguish detail under certain specific conditions. The measure of this ability is normally expressed in lines per millimeter or angular resolution. Equates to the shortest distance between two points that allows distinct identification of both points. USIS 95
resolution in bearing The minimum detectable separation of objects at the same range and the same elevation, expressed in terms of the horizontal angular distance between such objects. HDBK-850
resolution in elevation The minimum detectable separation of objects at the same range and same bearing, expressed in terms of the vertical angular distance. HDBK-850
resolution in range The minimum detectable separation of objects in the same line of sight, expressed in terms of the distance between them. HDBK-850
resolution limit In gravity and magnetic prospecting, the separation of two disturbing bodies at which some obvious indication, in a measured quantity, of the presence of two separate bodies ceases to be visible. HDBK-850
resolving power A mathematical expression of definition in an imaging system, usually stated as the maximum number of lines per millimeter that can be seen as separate lines in the image. HDBK-850
resolving power target A test chart used for the evaluation of photographic, optical, and electrooptical systems. The design usually consists of ruled lines, squares, or circles varying in size according to a specified geometric progression. HDBK-850
responder In general, an instrument that indicates reception of an electric or electromagnetic signal. See also transponder. HDBK-850
response time The ability to react to requests within established time criteria. To be operationally effective, the system must produce the desired output in a timely manner based on system category for routine or priority operations. [JOPES ROC]. DISA CFS
responsor A radio receiver which receives the reply from a transponder and produces an output suitable for feeding to a display system. HDBK-850
restitution (JCS) The process of determining the true planimetric position of objects whose images appear on photographs. [Restitution corrects for distortion resulting from both tilt and relief displacement.] HDBK-850
restoration The recovery of one or more lines or corner positions, or both, of a prior survey; the replacement of one or more lost corners or obliterated monuments by approved methods, including the substantial renewal of one or more monuments, as required for the purpose of a survey. HDBK-850
resultant error The error in any measurement that is the difference between the measured value and the true value for a quantity. Also called true error. HDBK-850
results The information returned to the client, which may include values as well as status information indicating that exceptional conditions were raised in attempting to perform the requested service. CORBA 2.2
resurvey A retracing on the ground of the lines of an earlier survey, in which all points of the earlier survey that are recovered are held fixed and used as a control. If too few points of the earlier survey are recovered to satisfy the control requirements of the resurvey, a new survey may be made. A resurvey is related directly to an original survey, though several resurveys may interpose between them. See also dependent resurvey; independent resurvey; retracement. HDBK-850
reticle (reticule) 1. (surveying) A system of wires, hairs, threads, etched lines, or the like, placed normal to the axis of a telescope at its principal focus, by means of which the telescope is sighted on a star, or target, or by means of which appropriate readings are made on some scale, such as a leveling or stadia rod. 2. (optics) A mark, such as a cross or system of lines, Iying in the image plane of a viewing apparatus and used singly as a reference mark in certain types of monocular instruments or as one of a pair to form a floating mark, as in certain types of stereoscopic instruments. See also floating mark; graticule; index mark; parallactic grid. HDBK-850
retouching Corrective treatment of a plate, negative, positive, or copy by means of brush, pencil, pen, airbrush, or other method. HDBK-850
retracement A term applied to a survey that is made for the purpose of verifying the direction and length of lines, and identifying the monuments and other marks of an established prior survey. See also resurvey. HDBK-850
retrodirective prism A prism consisting of a solid glass element having three mutually perpendicular reflecting surfaces and a fourth surface oblique to the three reflecting surfaces. A light beam entering through the oblique surface is reflected on each of the three other surfaces and turned 180 to be returned along the same airpath which it traveled to the retrodirective prism. HDBK-850
retrograde motion 1. Motion in an orbit opposite to the usual orbital direction of celestial bodies within a given system. Specifically, of a satellite, motion in a direction opposite to the direction of rotation of the primary. 2. The apparent motion of a planet westward among the stars. Also called retrogression. Opposite of progressive motion. HDBK-850
retrograde orbit A retrograde orbit is inclined greater than 90 degrees. An orbit inclined less than 90 degrees is a posigrade orbit. USIS 95
retrograde vernier A vernier scale which has spaces or divisions slightly longer than those of the primary scale. The numbers on the vernier scale run in the opposite direction from those on the primary scale. HDBK-850
retrogression See retrograde motion. HDBK-850
reusability The ability of a software or hardware component, built to fulfill a requirement for a system built to achieve a particular mission, to be used to meet a similar requirement for another system that is being built to address a different mission need. Reusability allows system development and maintenance costs to be reduced because they can be shared across multiple programs. DII COE IRTS
reuse, software The process of implementing or updating software systems using existing software assets. S/W Reuse
reverse stereo See pseudoscopic stereo. HDBK-850
reversible level A spirit level having a bubble tube with the inner surface ground barrel shaped so that the tangent lines to curves on the upper and lower sides are parallel when exactly opposite, permitting the level to be used in either the erect or inverted positions. HDBK-850
reversible pendulum A pendulum so designed and equipped with means of support that it may be used with either end up or down. HDBK-850
reversing in azimuth and altitude See double centering. HDBK-850
reverted image (optics) An image in which detail is in reverse order, from left to right, compared to the corresponding detail of the object. The order of detail from top to bottom remains unchanged. A mirror image. HDBK-850
revision The process of updating a product to reflect current information. TypicalIy, revision of a map or chart does not require significant changes to the horizontal position of features or vertical data values; rather, improvement in planimetric data is provided, Normally, publications are revised, not recompiled. HDBK-850
revisit frequency See periodicity. USIS 95
revisit time The total time between two valid imaging accesses. USIS 95
revolution 1. The turning of a body about an exterior point or axis. The correct distinction between revolution and rotation is given in the statement "the Earth revolves around the Sun, and rotates on its axis." 2. (surveying) A turning of an instrument or part of an instrument. HDBK-850
rhomboidal prism A prism that displaces the axis of the beam of light only laterally. HDBK-850
rhumb bearing The direction of a rhumb line through two terrestrial points, expressed as angular distance from a reference direction. It is usually measured from 0 at the reference direction clockwise to 360. Also called Mercator bearing. HDBK-850
rhumb direction See Mercator direction. HDBK-850
rhumb line A line on the surface of the Earth cutting all meridians at the same angle. [A loxodrome or loxodromic curve spiraling toward the poles in a constant true direction. Parallels and meridians, which also maintain constant true directions, may be considered special cases of the rhumb line. A rhumb line is a straight line on a Mercator projection.] Also called equiangular spiral; loxodrome; loxodromic curve; Mercator track. HDBK-850
rhumb line distance Distance along a rhumb line, usually expressed in nautical miles. HDBK-850
ridge line A graphic representation of major ridges used to give more definition to the topographic character of an area for the determination of low altitude radar predictions. They are shown only in areas of rise gradient to depict those places in which the elevated terrain forms a sufficient background to partially screen vision at low altitude. HDBK-850
right ascension The angular distance measured eastward on the Equator from the vernal equinox to the hour circle through the celestial body, from 0 to 24 hours. HDBK-850
right ascension system An equatorial system of curvilinear celestial coordinates which has the Equator as the primary reference plane and the perpendicular hour circle through the vernal equinox as the secondary reference plane. The direction to a body is given by its right ascension and declination. HDBK-850
right bank That bank of a stream or river on the right of the observer when he is facing in the direction of flow, or downstream. HDBK-850
right sphere The celestial sphere as it appears to an observer at the Equator, where celestial bodies appear to rise vertically above the horizon. HDBK-850
right-angle prism A prism that turns a beam of light through a right angle. It inverts (turns upside down) or reverts (turns right for left) according to the orientation of the prism. HDBK-850
right-reading A descriptive term for an image which, when viewed through the base, reads the same as the original. Other terms sometimes used to identify image direction, such as normal reading, natural readings, etc., are not recommended because of possible confusion in negative-positive relationship. HDBK-850
rigid tripod engraver A scribing instrument with three points of contact surface, to absorb the normal imbalance of the operator's hand pressure. HDBK-850
ring (digital mapping) An edge which is a member of a different closed loop of edges. HDBK-850
ring A 1-dimensional element described by a minimum set of connected edges forming a loop. ISO/TC 211
rise 1. To cross the visible horizon while ascending. 2. (satellite surveying) To cross the observer's horizon while ascending; detectable by broadcast data received. HDBK-850
rise gradient A color-coded omnidirectional graphic representation of those terrain slopes which are predicted to be low altitude radar significant. HDBK-850
rise time The time at which a satellite's broadcast can be picked up by a suitably equipped observer, as taken from an alert. Set time and time of closest approach are also given. See also alerts; rise. HDBK-850
rising tide See flood tide. HDBK-850
river crossing (leveling) Carrying a line of levels across a stream or other body of water, when no suitable bridge is available and the width of the body of water is greater than the maximum allowable length of sight for the leveling, requires a special series of observations which taken collectively is known as a river crossing. HDBK-850
riverine area (JCS) An inland or coastal area comprising both land and water, characterized by limited land lines of communication, with extensive water surface and/or inland waterways that provide natural routes for surface transportation and communications. HDBK-850
road map A medium-or small-scale special-purpose map, generally showing only planimetric detail, with emphasis upon the road network and related data. Its main purpose is to furnish pertinent road information for tactical and administrative troop movement. HDBK-850
road net (JCS) The system of roads available within a particular locality or area. HDBK-850
roamer (JCS) Grids constructed to common map scales used for determination of map coordinates. HDBK-850
rod See leveling rod. HDBK-850
rod correction (leveling) That correction which is applied to an observed difference of elevation to correct for the error introduced when the leveling rods are not actually of the length indicated by the graduations. HDBK-850
rod float A small cylindrical tube of any material, closed at the bottom and weighted with shot until it floats in an upright position with about 2 to 6 inches projecting above the water surface. Current velocities are determined by direct observations. HDBK-850
rod level An accessory for use with a leveling rod or a stadia rod to assure a vertical position of the rod prior to instrument reading. HDBK-850
rod sum (leveling) The algebraic total of plus and minus sights in a given level line. HDBK-850
role Identifier for a behavior, which may appear as a parameter in a template for a composite object, and which is associated with one of the component objects of the composite object. RM-ODP
roll (JCS) 1. The rotation of an aircraft or ship about its longitudinal axis. 2. In air photography, the camera rotation about the longitudinal access of the aircraft. Also called tilt. See also tilt angle. HDBK-850
romanization 1. The process of recording in roman script either the sounds of a language or the graphic symbols of a nonroman writing system. 2. An item of a language which has undergone this process. See also transcription; transliteration. HDBK-850
roof prism A type of prism in which the image is reverted by a roof, that is, two surfaces inclined at 90 to each other. HDBK-850
root mean square error See standard error. HDBK-850
roots of mountain theory See Airy theory of isotasy. HDBK-850
rotating prism See dove prism. HDBK-850
rotating prism camera A class of panoramic camera in which a double dove prism is rotated while the lens system remains fixed. This configuration can achieve a scan of 180 or more. HDBK-850
rotation 1. (astronomy) A turning of a body about a self-contained axis, as the daily rotation of the Earth. HDBK-850
rotational movement (photogrammetry) The systematic rotation of projectors or projector assemblies. When applied to the projector body within the gimbal inner ring, the movement is about the z-axis and is called swing. Rotation of the inner ring is about an x-axis (secondary axis) and is called x-tilt. Rotation of the outer ring is about a y-axis (primary axis) and is called y-tilt. HDBK-850
route chart 1. A chart showing routes between various places, usually with distances indicated. 2. An aeronautical chart covering the route between specific terminals, and usually of such scale as to include the entire route on a single chart. Also called flight chart. HDBK-850
route map A map showing roads to be followed and nearby points of military significance. HDBK-850
route survey Surveys for linear construction such as railroads, highways, and transmission lines which include the layout of lines and grades for these projects. HDBK-850
router Generically, any machine responsible for making decisions on which path out of several different paths, network traffic will follow. [Comer] [DISA/DO3 (CIO)] DISA CFS
Routing Indicator (RI) A group of letters, used in ACP 127 messaging, assigned to identify a station within a tape relay network to facilitate routing of traffic. The RI indicates the status of the station and may indicate its geographical area. Ris are composed in accordance with the Routing Indicator Plan described in the ACP 121 series and are used to define the network address of a Communications Center (COMCEN) serving one or more organizations. [DISA/D2] DISA CFS
row (digital) An ordered collection of fields in a data base pertaining to an entity or record. HDBK-850
rubber blanket See offset lithography; offset press. HDBK-850
rubber sheeting A rectification process which resamples data to transform (stretch or compress) it from one statistical model to fit another model. HDBK-850
rubber sheeting (image warping) Any geometric manipulation of an image to control points that does not involve the use of a photogrammetric math model. OGC RFI
rubberband The ability to fix the ends of a line, or selected points along a line, in a static position and then "stretch" the line between the fixed points to establish new geometric shapes. HDBK-850
rule Statement that defines or constrains some aspect of the enterprise. C4ISR AF
run 1. (lithography) The number of impressions made on a press for a given sheet. 2. (micrometer) See error of run. 3. (JCS) (aerial photography) That part of a flight of one photographic reconnaissance aircraft during which photographs are taken. HDBK-850
run of micrometer See error of run. HDBK-850
run-length code A data compression method for large homogenous regions of raster data. Data is recorded as tuples which designate the quantity of a repeating value and the value itself. Also known as run-length encoding (RLE). HDBK-850
running (leveling) A continuous series of measured differences of elevation, made setup by a setup in one direction along a section of a line of levels, which results in a measurement of the difference of elevation between the bench marks or other points, either temporary or permanent, at the ends of the section. HDBK-850
running fix (JCS) The intersection of two or more position lines, not obtained simultaneously, adjusted to a common time. HDBK-850
running mean See consecutive mean. HDBK-850
Runtime Environment {DII COE} The runtime context determined by the applicable account group, the COE, and the executing segments. The runtime environment definition is limited to just the context (environment variable settings, X configuration, background processes, task priorities, etc.) required for an application to execute. Environment settings for software development purposes are maintained separately from the runtime environment to avoid runtime conflicts between developer preference settings. DII COE IRTS
Runtime Infrastructure (RTI) The general purpose distributed operating system software which provides the common interface services during the runtime of an HLA federation. (HLA Glossary: http://hla.dmso.mil/hla/general/hlagloss.html) JTA 2.0

Last Updated by Mark Owens 26 January 1999.