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Term Definition/Description Source
vacuum box The frame, containing its own vacuum unit, which encloses the mold for the forming of plastic relief maps. HDBK-850
Vaisala Comparator A precise distance measuring instrument that uses optical interferometry for making measurements. It can measure distances as great as 864 meters with an accuracy of 1 part in 107. HDBK-850
validation The process of testing an application or system to ensure that it conforms to its specification. IEEE P1003.0
validation {C3I} For C3I systems, confirmation, by the Chairman of the Joint Chiefs of Staff, that mission needs identified can only be satisfied by a change in materiel and cannot be satisfied by a change in doctrine, operational concepts, tactics, training, or organization. DODI 4630.8
value Any entity that may be a possible actual parameter in a request. Values that serve to identify objects are called object references. CORBA 2.2
value See absolute value; adjusted value; most probable value; observed value; true value. HDBK-850
value domain A set of accepted values. ISO/TC 211
Value-Added Network (VAN) Communications network that transmits, receives, and stores EDI [Electronic Data Interchange] messages for EDI trading partners. [DISA/D2] DISA CFS
vanishing line The straight line on a photograph upon which lie all the vanishing points of all systems of parallel lines parallel to one plane. HDBK-850
vanishing point The image, in the plane of a photograph, of the point toward which a system of parallel lines in the object space converges. HDBK-850
variable contour interval A nonuniform contour interval. It may result from the use of cartographic source materials which do not contain a constant contour interval or from adapting the contour interval to specific types of terrain for the optimum portrayal of relief features. HDBK-850
variable length field A field whose length is determined by the amount of storage needed to store its contents. Useful for character strings and coordinate strings, both of which are highly variable in length. HDBK-850
variable length records These records may have a variable number of fields (data elements) or the fields may be of varying length, or both. Variable-length records typically have delimited fields and/or byte counts to facilitate processing. See also fixed-length records. HDBK-850
variable perspective camera system A system which, in its simplest form, consists of a standard-type view camera, a large aperture front-surface mirror of spherical configuration, and an easel used in the rectification of highly tilted long focal-length photographs, and the transformation of maps and charts from one projection to another. When the camera component is replaced with a projector, it becomes possible to expedite the rectification of lunar photography taken by terrestrial observatories. HDBK-850
variable ratio pantograph See pantograph. HDBK-850
Variance (S 2) The most commonly used measure of dispersion or error in statistical analysis. It is also called the mean squared deviation. [An estimate of] variance is calculated by first taking the sum of the squared deviations from the mean for each of n observations. Then the sum is divided by n-1. HDBK-850
variation See magnetic variation. HDBK-850
variation of coordinate method A method of adjusting measurements in which the coordinates of geodetic points are varied so as to best fit the observations and retain mathematical homogeneity. See observation equations; variation of parameters. HDBK-850
variation of latitude A small change in the astronomic latitude of points on the Earth, due to variation of the poles. HDBK-850
variation of parameters 1. An interactive method to solving complex equations by successively closer approximations of the variables, usually employing the more significant terms of the first derivatives of mathematically precise functions that must equal zero only when the correct values of the variables are used to compute the functions. 2. The observation equations method of least squares adjustment is sometimes referred to as the variation of parameters method of least squares adjustment because the parameters of observation equations are determined by variation of parameters. HDBK-850
variation of the poles A small variation of the location of the instantaneous axis of rotation of the Earth with respect to the physical surface thereof. Also called polar motion. See also conventional international origin. HDBK-850
variational inequality An inequality in the Moon's motion, due mainly to the tangential component of the Sun's attraction. HDBK-850
variometer An instrument for comparing magnetic forces, especially of the Earth's magnetic field. HDBK-850
vectograph A stereoscopic photograph composed of two superimposed images that polarize light in planes 90 apart. When these images are viewed through Polaroid spectacles with the polarization axes at right angles, an impression of depth is obtained. HDBK-850
vector 1. A quantity possessing both magnitude and direction. 2. (data structure) A data structure which emphasizes position. Homogeneous units are points, lines, and polygons. 3. A directed line segment, with magnitude commonly represented by the coordinates for the pair of end points. 4. (Computer Programming/Mathematics) Vector data refers to data in the form of an array with one dimension. HDBK-850
vector data Data which represents each cartographic feature by an entity description (feature code) and a spatial extent (geographic position). Geographic position may be two-dimensional (horizontal position only) or three-dimensional (including elevation). Features are categorized as point, line, or area features. The position of a point feature is described by a single coordinate pair (or triplet for three dimensional data). The spatial extent of a line feature is described by a string of coordinates of points lying along the line, while the extent of an area feature is described by treating its boundary as a line feature, Vector data may be stored in a sequential, a chain node, or a topological data structure. HDBK-850
vector data Data represented by geometric primitives. ISO/TC 211
vector displays and databases Databases that build all geographic features from points, that is from discrete X-Y locations. Lines are constructed from strings of points, and polygons (regions) are built from lines which close. OpenGIS Guide
vector map Map data based on a graph theory data model . ISO/TC 211
vector map product (VMP) A generic term used to describe an electronic map display product, in vector form. The VMP could be line segments (vectors), points or area polygon delineated areas, displayed as such or symbolized. The features may be attributed as to surface material, structural composition, or radar significance. For visual displays color fill software may be required. HDBK-850
vector methods In geoprocessing, methods of representing geographic feature from points, lines, and polygons, as opposed to raster techniques which record geographic features within a matrix of grid cells. The choice between vector and raster GIS has much to do with the application being considered since both methods have strengths and weaknesses. Many current GIS permit transformation between vector and raster input and output. OpenGIS Guide
Vector Product Format (VPF™) A geo-relational data structure designed for the provision of vector products on CD-ROM media and manipulated in geographic information system (GIS) environments. HDBK-850
Vector Product Standard (VPS) A suite of user system oriented standards encompassing VPF digitizing conventions, tiling, feature attributing and coding. See also Vector Product Format (VPF™). HDBK-850
vector quantization A lossy compression technique in which blocks of data are matched to a limited set of defined blocks called codewords. HDBK-850
vector refresh display A cathode ray tube on which the image is displayed as a vector and which must be refreshed by a new pass of the electron beam about 30 times a second. HDBK-850
Vector Smart Map Level 0 (VMap 0™) VMap0™ data will be captured from hardcopy cartographic sources supplemented by aerial imagery where no hardcopy is available. Collection criteria will be consistent with Operational Navigation Chart (ONC) and Jet Navigation Chart (JNC) data collection procedures. This product is quite similar to the Digital Chart of the World (DCW) product issued in previous years but is based on the FACC feature/attribute coding scheme used in other Vector Product Format (VPF™) products. VMap 0™ will provide military forces with digital terrain feature information to support mission planning functions as quickly as possible. As mission data requirements evolve from initial planning to more detailed operational activities, more detailed VPF™ products such as Digital Nautical Chart (DNC™), Vector Smart Map Level 1 (VMap 1™), Vector Smart Map Level 2 (VMap 2™), Urban Vector Smart Map (UVMap™), and VPF Interim Terrain Data (VITD™) should be employed. NIMA Web Site
Vector Smart Map Level 1 (VMap 1™) The geographic extent of the VMap 1™ product is global and consists of multiple regional databases. The feature content in the VMap 1 Product Specification is based on the feature content defined in the referenced NIMA Product Specifications. At least initially, NIMA's 1/250,000 Scale Joint Operations Graphics Series 1501 and Series 1501 Air will be used as the database source for VMap 1™. However, the resolution of features and attributes defined in the VMap 1™ Product Specification is robust enough to support collection from imagery. The VMap 1™ Product is intended for military planners at the operational and, to a limited extent, the tactical level of operations. Due to the scale and feature content of the VMap 1 source data, the product is not well suited to terrain analysis. If no other data is available, limited geographic information system (GIS) applications can be conducted using this product. VMap 1™ data is suitable for use by both ground and air commanders. See also Vector Smart Map Level 0 (VMap 0™), Vector Smart Map Level 2 (VMap 2™), and Urban Vector Smart Map (UVMap™). NIMA Web Site
Vector Smart Map Level 2 (VMap 2™) VMap 2™ databases are constructed from several sources in a variety of formats, primarily topographic maps at scale 1:50,000 and scale 1:100,000. These are supplemented with image and textual data as available during the production process. Since the primary sources are cartographic in nature, users should anticipate that the attribution of features is incomplete. VMap 2™ is intended for use by tactical planners and generally fills the role of geographic information found on paper maps at scales of 1:50,000 and 1:100,000. Limited spatial analysis (military GIS) applications are also possible but users are cautioned that the symbolized nature of the source data (paper maps) introduces spatial errors into the product since the precise geographic coordinates of every feature are largely unknown. See also Vector Smart Map Level 0 (VMap 0™), Vector Smart Map Level 1 (VMap 1™), and Urban Vector Smart Map (UVMap™). NIMA Web Site
Vector Vertical Obstruction Data (VVOD™) The VVOD™ is a vector-based digital database containing obstruction features. VVOD™ prototype data was derived from DVOF (DMA Vertical Obstruction File) data. Powerline information was extracted from JOG sheets. VVOD™ also functions as a mission specific data set designed to support geographic information system (GIS) applications. The database shall contain all manmade vertical obstructions on the Earth's surface which are sufficiently tall so as to pose a hazard to powered flight, both manned and unmanned. NIMA Web Site
vectorial angle The angle between the fixed line to which the direction is referred and the radius vector. See also polar coordinates. HDBK-850
velocity correction A correction applied to the speed of light to obtain the true speed in consideration of humidity, temperature, and altitude for use in shoran operations. HDBK-850
Vening Meinesz formulas Formulas for computing deflections of the vertical from gravity data. HDBK-850
verbal scale See equivalent scale. HDBK-850
verification testing The process of proving mathematically whether an IUT is correct, consistent and complete. NOTE - Compare with falsification testing. ISO/TC 211
verify 1. To determine whether a transcription of data or other operation has been accomplished accurately. 2. To confirm the accuracy, portrayal, and completeness of digital data with respect to established standards or specifications. HDBK-850
vernal equinox That point of intersection of the ecliptic and the celestial equator, occupied by the Sun as it changes from south to north declination, on or about 21 March. Also called first of Aries; first point of Aries; March equinox. See also mean equinox. HDBK-850
vernier A short, auxiliary scale situated alongside the graduated scale of an instrument, by means of which fractional parts of the smallest division of the primary scale can be measured accurately. See also contact vernier; direct vernier; folding vernier; optical vernier; retrograde vernier. HDBK-850
vernier closure The difference between the initial and final vernier readings during the survey operation of closing the horizon. HDBK-850
vertex (vertices) The highest point. The vertices of a great circle are the points nearest the poles. Also called apex. HDBK-850
vertex of curve See point of intersection. HDBK-850
vertical The line perpendicular to the geoid at any point. Lt is the direction in which the force of gravity acts. See also local vertical; mass attraction vertical; normal, definition 3. HDBK-850
vertical angle 1. An angle in a vertical plane. 2. (surveying) One of the directions which form a vertical angle is usually either the direction of the vertical (zenith), and the angle is termed the zenith distance; or the line of intersection of the vertical plane in which the angle lies with the plane of the horizon, and the angle is termed the angle of elevation or angle of depression, or simply the altitude (plus or minus, as the case may be). The vertical angle between two directions, neither of which lies in the plane of the horizon or coincides with the vertical, is usually obtained from the combination of two vertical angles as defined above. HDBK-850
vertical angulation The process of obtaining differences of elevation by means of observed vertical angles, combined with lengths of lines. In geodetic work, trigonometric leveling is used with the same meaning. HDBK-850
vertical axis (theodolite, transit) The line through the center of the instrument about which the alidade rotates. For an instrument in complete adjustment, this axis occupies a vertical position, passes through the center of the horizontal circle, and is perpendicular to its plane. HDBK-850
vertical bridging See bridging. HDBK-850
vertical circle 1. A great circle of the celestial sphere, through the zenith and nadir. Vertical circles are perpendicular to the horizon. 2. A graduated disk mounted on an instrument in such a manner that the plane of its graduated surface can be placed in a vertical plane. It is primarily used for measuring vertical angles in astronomic and geodetic work. HDBK-850
vertical collimator A telescope so mounted that its collimation axis can be made to coincide with the vertical (or direction of the plumb line). The vertical collimator serves as an optical plumb line; it may be designed for use in placing a mark on the ground directly under an instrument on a high tower or in centering an instrument on a high tower directly over a mark on the ground. Also called optical plummet. HDBK-850
vertical comparator (pendulum) A stand designed for the support of a pendulum, a bar of known length, and two micrometer microscopes, so placed with reference to one another that the length of the pendulum can be measured. HDBK-850
vertical control The measurements taken by surveying methods for the determination of elevation only with respect to an imaginary level surface, usually mean sea level. See also survey net, definition 2. HDBK-850
vertical control datum Any level surface (as, for example, mean sea level) taken as a surface of reference from which to reckon elevations. Also called vertical datum; vertical geodetic datum. See also datum level; reference level; reference plane. HDBK-850
vertical control net See survey net, definition 2. HDBK-850
vertical control point See control point; control station. HDBK-850
vertical coordinate system (A&D LDM Entity: "VERTICAL-COORDINATE-SYSTEM") The refernce frame or system from which vertical distances (altitudes or depths) are measured. A&D LDM
vertical coordinates The vertical distance of a point above or below a reference datum. Points may be plus or minus according to whether the point is above or below the datum. HDBK-850
vertical curve A parabolic curve used to connect grades of different slope, and used at the vertex of a grade to avoid the sudden change in direction in passing from one grade to the other. This method of grade change is usually used when there is an algebraic difference of more than 0.2 percent in the two opposing grades. HDBK-850
vertical datum Any datum which serves as a reference for defining height. EXAMPLE: geocentric ellipsoidal datum for defining ellipsoidal height, geoid model for orthometric height. CEN/TC 287
vertical datum See vertical control datum. HDBK-850
vertical datum (vertical reference) The surface used as a reference for defining elevation. NOTE - In the case of geodetic ellipsoidal height, the vertical datum is the ellipsoid of the geodetic datum. In the case of height above mean sea level, the vertical datum is a local determination or global model of mean sea level. ISO/TC 211
vertical deformation In relative orientation, the cumulative model warpage affecting the vertical datum from x-tilt error and y-tilt error. HDBK-850
vertical domain A domain which addresses aspects of a single function or application area. Examples include payroll systems, automated weapons systems, robotic control systems. A vertical domain draws on capabilities from any horizontal domains that support its purpose. Compare with horizontal domain. S/W Reuse
vertical exaggeration 1. The change in a model surface created by proportionally raising the apparent height of all points above the base level while retaining the same base scale. 2. The increase of the vertical scale over the horizontal scale of a terrain model or plastic relief map. HDBK-850
vertical extension See extension, definition 2. HDBK-850
vertical geodetic datum See vertical control datum. HDBK-850
vertical intensity The magnetic intensity of the vertical component of the Earth's magnetic field, reckoned positive if downward, negative if upward. HDBK-850
Vertical Obstruction Data (VOD) See Probablistic Vertical Obstruction Data (PVOD). NIMA LOP
vertical parallax See y-parallax. HDBK-850
vertical pass point See supplemental elevation. HDBK-850
vertical photograph An aerial photograph taken with the axis of the camera being maintained as closely as possible to a truly vertical position with the resultant photograph laying approximately in a horizontal plane. HDBK-850
vertical plane 1. Any plane passing through a point on the Earth and containing the zenith and nadir of that point; also a plane containing a plumb line. 2. (surveying) A plane at right angles to a horizontal plane and within which angles and distances are observed. HDBK-850
vertical reference datum (UCDM Entity: "VERTICAL-REFERENCE-DATUM") A defined surface to which vertical measurements are referenced. USIGS/CDM-A
vertical sketchmaster A type of sketchmaster in which vertical photographs are utilized. HDBK-850
vertical stereotriangulation That portion of stereotriangulation concerned with the establishment of vertical data. Vertical stereotriangulation is often limited or precluded as an operation due to the more rigid accuracy standards established for vertical positions than for horizontal positions. HDBK-850
vertical strip A single flightline of overlapping photos. Photography of this type is normally taken of long, narrow targets such as beaches or roads. USIS 95
vertical-angle bench mark (VABM) A bench mark with elevation established by vertical angle methods. See also bench mark. HDBK-850
vertical-angle station See supplemental station. HDBK-850
vertical-obstruction (A&D LDM Entity: "VERTICAL-OBSTRUCTION") A feature that has a significant elevation above the terrain level. A&D LDM
vertices The points of termination or intersections of lines that form a polygon. Each point is expressed by a latitude and longitude. USIS 95
very high frequency (VHF) The frequency spectrum ranging from 30 MHz - 300 MHz. USIS 95
Very Large Data Storage (VLDS) tape A medium for storing digital image data. USIS 95
vibration A single movement of a pendulum in either direction, to or fro. See also oscillation. HDBK-850
video Electro-optical imaging sensors and systems which generate sequential or continuous streaming imagery at specified rates. Video standards are developed by recognized bodies such as ISO, ITU, SMPTE, EBU, etc. [VISP (Video Imagery Standards Profile)] JTA 2.0
video A sequence of still images captured over a fixed time, at a fixed frame rate, and transmitted and displayed in synchronous order giving the appearance of live motion (e.g., video broadcasts, synthetic video, finished intel products). Multimedia
video conferencing A form of teleconferencing that employs voice and video communications, usually accomplished using digital channels that operate at 56 Kbps to 1.544 Mbps. See also video teleconferencing (VTC). Multimedia
video disc [MCGT] A 30.5 cm (12") Constant Angular Velocity (CAV) analog video disc capable of storing video images on each side (equivalent to approximately 200 average-sized map sheets at two different fields of view). See also CD-ROM. HDBK-850
video display terminal (VDT) Terminal composed of a keyboard for data input and a CRT screen for display of the input/output. [HCI Style Guide] DISA CFS
video map Any one of a series of cartographic products that are captured, stored, and displayed using analog video signals. HDBK-850
video on demand A proposed video service that would enable a consumer to select a video (or movie) and play it using VCR-like controls (play, stop, rewind, fast forward, pause). Multimedia
video server A computer that serves digital video streams to one or more client devices. Used extensively for video-on-demand. Multimedia
Video Support Product Imagery-based product developed and prepared by the Marine Corps Intelligence Activity (MCIA). A unique combination of annotated imagery, photos, maps, and charts on VHS or 8mm video format that provides mission-specific area overviews ("living mosaics") and planning information. Contains all-source information in narrative and supporting video graphics. USIS 95
video teleconferencing (VTC) A means of televising and transmitting a meeting between two or more organizations. [JITC Dictionary] See also video conferencing. DISA CFS
view A way of showing or seeing something from a particular position, to support a specific function or theme. ISO/TC 211
view {RDBMS} SQL "Select", Statement, used to provide temporary information about a given table(s) of a Database Management System without actually creating a subset or new table. OpenGIS Guide
viewfinder (aerial camera) An auxiliary device which shows the field of view of a camera. It is used in the taking of vertical aerial photography to correct crab angle and maintain forward lap (end lap). HDBK-850
viewpoint language Definitions of concepts and rules for the specification of a system from a particular viewpoint. The standard viewpoint languages include: Enterprise Language, Information Language, Computational Language, Engineering Language, and Technology Language. See [ISO 96] Part 3 for details. RM-ODP
viewpoint of a system A form of abstraction achieved using a selected set of architectural concepts and structuring rules, in order to focus on particular concerns within a system. Viewpoints often represent the perspective of a particular stakeholder or technical expert involved in the system. The viewpoint model addresses their issues and concerns. There are 5 standard viewpoints of a system: Enterprise, Information, Computational, Engineering, and Technology. RM-ODP
views, architecture Perspectives that logically combine to describe an architecture. See data architecture (view); operational architecture view; systems architecture view; technical architecture view. C4ISR AF
vignetting 1. (photography) A gradual reduction in density of parts of a photographic image due to the stopping of some of the rays entering the lens. Thus, a lens mounting may interfere with the extreme oblique rays. An antivignetting filter is one that gradually decreases in density from the center toward the edges; it is used with many wide-angle lenses to produce a photograph of uniform density by cutting down the overexposure of the center of the photograph. 2. (lithography) A photographic process which portrays a solid color in a screen which shades off gradually into the unprinted paper. Open water is often shown by this method. HDBK-850
virtual gravity The force of gravity on an atmospheric parcel, reduced by centrifugal force due to the motion of the parcel relative to the Earth. HDBK-850
virtual image An image that cannot be shown on a surface but is visible, as in a mirror. HDBK-850
virtual PPI reflectoscope (VPR) chart A type of radar chart. HDBK-850
virtual reality The art/science of creating worlds that are totally rendered by computers in which the user can immerse himself and take 360-degree perspectives. Multimedia
visibility chart A special-purpose map or other graphic showing which areas can be seen and those which cannot be seen from a given observation point. HDBK-850
visible horizon See apparent horizon. HDBK-850
visible light That portion of the electromagnetic spectrum ranging from about 0.4 to about 0.75 microns. USIS 95
visible near infrared The preferred term for the shorter wavelengths in the infrared region extending from about 0.78 micrometers (visible, red) to around 2.5 micrometers. USIS 95
visual acuity A measure of the ability of the human eye to separate details in viewing an object. The reciprocal of the minimum angular separation, in minutes of arc, of two lines of detail which can be seen separately. HDBK-850
visual range The limiting range of a light determined after taking into account both the geographic range and the luminous range. The geographic range is the maximum distance at which the curvature of the Earth permits a light to be seen from a particular height of eye without regard to the luminous intensity of the light. The luminous range is determined from the known nominal luminous range, called the nominal range, and the existing visibility conditions. HDBK-850
voice-activated switching Used in multiway video conferencing so that all participating sites automatically see the site which is currently speaking. Multimedia
voting {TERCOM} The technique of having a vehicle fly over the terrain covered by three unique but complementary maps within a finite distance, comparing the calculated positional accuracy within each of the maps and determining whether or not to update the vehicle navigation system based on how closely the three positional accuracies compare with each other, HDBK-850
voxel A two-dimensional element that is the smallest nondivisible element of a digital volume ISO/TC 211
VPF Interim Terrain Data (VITD™) VITD™ is a vector-based digital product that portrays selected military geographic information containing features of tactical military significance in a standardized georelational format. VITD™ is designed to support military terrain analysis (military GIS) for land forces in Division and smaller sized elements. It is also suitable for planning and terrain analysis in support of special operations. NIMA Web Site
vulgar establishment See establishment of the port. HDBK-850

Last Updated by Mark Owens 17 February 1999.