地理信息系統(tǒng)常用詞匯和短語和英文釋義

./地理信息系統(tǒng)常用詞匯及短語及其英文釋義Acceptancetest Atestforevaluatinganewlypurchasesystem'sperformanceandconformitytospecifications. Accesstime Ameasureofthetimeintervalbetweentheinstantthatdataarecalledfromstorageandtheinstantthatdeliveryiscomplete Accuracy Conformancetoarecognizablestandard;canoftenmeanthenumberofbitsinacomputerwordavailableinagivensystem<seePrecision>.Thestatisticalmeaningofaccuracyisthedegreewithwhichanestimatedmeandiffersfromthetruemean.SeePrecision. Acousticcoupler Adevicethatenablesacomputerterminaltobelinkedtoanotheroverthetelephonesystemviathehandsetofaconventionaltelephone. ActiveSystem Inremotesensing,asystemthatprovidesitsownsourceoftheelectromagneticradiationtobereflectedorscatteredbytheobjectbeingsensed.Forexample,radarisanactivemicrowavesystemsincetheradarsystememitsenergywhichislaterdetected.Incontrasttoapassivesystem. Addressablepoint Apositiononavisualdisplayunit<VDU>thatcanbespecifiedbyabsolutecoordinates. Addressability Thenumberofpositions<pixels>intheXandYaxexonaVDUorgraphicsscreen. Algorithm Asetofrulesforsolvingaproblem.Analgorithmmustbespecifiedbeforetherulescanbewritteninacomputerlanguage. Aliasing 1.Theoccurrenceofjaggedlinesonaraster-scandisplayimagewhenthedetailexceedstheresolutionofthescreen. 2.InFourieranalysistheeffectofwavelengthsshorterthanthosesampledbytheobservationpointsontheformoftheestimatedpowerspectrum. Alphanumericcode Machineprocessableletters,numbersandspecialcharacters.Hencealphanumericscreen,alphanumerickeyboardfordisplayingandenteringaphanumericcharacters. Alphanumeric Consistingofbothlettersandnumbers. AmericanNationalStandardsInstitute<ANSI> AnassociationformedbytheAmericangovernmentandindustrytoproduceanddisseminatewidelyusedindustrialstandards. AmericanStandardCodeforInformationInterchange<ASCII> Awidelyusedindustrystandardcodeforexchangingalphanumericcodesintermsofbit-signatures. Analog<oranalogue> Acontinuouslyvaryingelectronicsignal<contrastwithDigital>. AncillaryData Additional,supplementaldata. AngularFieldofView SeeFieldofView<FOV> Application Ataskaddressedbyacomputersystem. Applicationprogramorpackage Asetofcomputerprogramsdesignedforaspecifictask. Arc Alineconnectingasetofpointsthatformonesideofapolygon.SeeChain,andString. Archivalstorage Magneticmedia<tapes,removabledisks>usedtostoreprogramsanddataoutsidethenormaladdressablememoryunitsofthecomputer. Area Afundamentalunitofgeographicalinformation.SeePoint,andLine. Array Aseriesofaddressabledataelementsintheformofagridormatrix. Arrayprocessor aspecialhardwareboardforhigh-speedprocessingofdataencodedonamatrix. Assembler Acomputerprogramthatconvertsprogrammer-writteninstructionsintocomputer-executable<binary>instructions Assemblylanguage Alow-level<primitive>programminglanguagethatusesmnemonicsratherthanEnglish-likestatements. Associateddata Seeattribute Attribute Non-graphicinformationassociatedwithapoint,line,orareaelementinaGIS. Autocorrelation,autocovariance Statisticalconceptsexpressingthedegreetowhichthevalueofanattributeatspatiallyadjacentpointscovarieswiththedistanceseparatingthepoints. Automatedcartography Theuseofanykindofautomationindataprocessing. automatedGeographicInformationSystem<AGIS> Ageographicinformationsystembasedondigitalcomputers. Auxiliarystorage Addressablememorydevicesoutsidethemainmemoryofthecomputersuchasdisksandtapeunits. Backgroundprocessin/mode Taskssuchasprintingaregivenalowerprioritybythecomputerthanthoserequiringdirectuserinteraction. Back-up Makingacopyofafileorwholediskforsafekeepingincasetheoriginalislostordamaged. Band Arangeofwavelengthsofelectromagneticradiation;synonymforthetermchannel. BandInterleavedbyLine<BIL> Aspecificimplementationofamultivariaterasterdataset.Foreachlineintheraster,thevaluesofeachofthevariablesorbandsarestoredinsequence,beforethesetforthesucceedingline. BandInterleavedbyPixel<BIP> Aspecificimplementationofamultivariaterasterdataset.Foreachpixel,thevaluesofeachofthevariablesorbandsarestoredbeforemovingontothenextpixel. BandSequential<BSQ> Aspecificimplementationofamultivariaterasterdataset.Thecompletedataarrayforeachseparatevariableorbandisstoredindependentlyoftheothervariables. BASIC Beginner'sAll-purposeSymbolicInstructionCode.Asimple,high-levelcomputerthanthoserequiringdirectuserinteraction. Batchprocessing Theprocessingofagroupofsimilarjobsonthecomputerwithoutoperatorintervention. Baudrate Ameasureofthespeedofdatatransmissionbetweenacomputerandotherdevices-equivalenttobitspersecond. Benchmarktest Atesttoevaluatethecapabilitiesofacomputersystemintermsofthecustomer'srequirements. Binaryarithmetic Themathermaticsofcalculatinginpowersoftwo. Binarycodeddecimal theexpressionofeachdigitofadecimalnumberintermsofasetofbits. Bit Thesmallestunitofinformationthatcanbestoredandprocessedinacomputer.Abitmayhavetwovalues-0or1;i.e.YES/NO,TRUE/FALSE,ON/OFF. Bitmap Apatternofbits<i.e.ON/OFF>onthegridstoredinmemoryandusedtogenerateandimageonarasterscandisplay. Bitplane Agriddedmemoryinagraphicsdeviceusedforstoringinformationfordisplay. Bitsperinch<BPI> Thedensityofbitsrecordedonamagnetictapel.800,1600,and6500arecommonstandards. BitsPersecond<BPS> Ameasurementofthespeedofdatacommunications. Bootup Tostartupacomputersystem. Bug AnerrorinacomputerprogramorIapieceofelectroicsthatcausesittofunctionimproperly. Bulkmemory Anelectronicdevicesuchasdisksortapesthatallowthestorageoflargeamountsofdata. Bus Acircuit,orgroupofcircuitsthatprovideacommunicationpathbetweenthecomputerandperipherals. Byte Agroupofcontiguousbits,usuallyeight,thatrepresentacharacterandwhichareoperatedonasaunit.Thernumberofbytesisusedtomeasurethecapacityofmemoryandstorageunits,e.g.256kbyte,300Mbyte. C Ahighlevelprogramminglanguageusedingraphics. CAD/CAM Computer-AidedDesign/ComputerAidedManufacturing.SeveralCAD/CAMsystemsalsoincludemajorfeaturesforGISandautomatedmapping. Calibration Determiningtherelationshipbetweenmeasurementswithaninstrumentandstandardor"known"values. Camera Adeviceforrecordinimagesonasensitizedsubstrate,usingoneormorelensestofocusthelightonthesubstrate,andashuttertodelimittheexposure. Cartography ThescienceandpracticeofrepresentingthefeaturesoftheEarth'ssurfacegraphically. Catalog Acollectionofdetailedinformationaboutwholedatasets. Cartridgedisk Atypeofmagneticmemorydiskenclosedinaplasticcartridge. CathodeRayTube<CRT> Anelectronicscreenfordisplayinginformationorgraphics.Alsocalledavisualdisplaydevice<VDU>. Cell Thebasicelementofspatialinformationintheraster<grid>descriptionofspatialentities. CensusTract IntheU.S.,smallareasaveraging4000inpopulation.TheyrepresentneighborhoodshavingsimilarsocioeconomiccharacteristicsandaredefinedcooperationwiththeU.s.BureauoftheCensus. Centralprocessingunit<CPU> Thepartofthecomputerthatcontrolsthewholesystem. Channel Inremotesensing,aspecifiedspectralintervalalsoreferredtoasaband. Chain Asequenceofcoordinatesdefiningacomplexlineorboundary.SeeArc,andString. Character Analphabetical,numericalorspecialgraphicsymbolthatistreatedasasingleunitofdata. Characterspersecond<CPS> Ameasureofthespeedwithwhichadevice<usuallyaprinteroraVDU>canprocessdataintheformofcharacters. Choroplethmap Amapconsistingofareasofequalvalueseparatedbyabruptboundaries. CoastalzoneColorScanner<CZCS> AmultispectralsensorthatflewontheNimbus7satellite.Thesensorwasdesignedtoregisterthecolorofoceanwaterasanindicationoftheamountofphytoplanktonandothermatterinthewater. Code Asetofspecificsymbolsandrulesforrepresentingdataandprogramssothattheycanbeunderstoodbythecomputer.SeeASCII,FORTRANPASCAL,etc. Colourdisplay ACRTcapableofdisplayingmapsandresultsincolour. ColourInfraredFilm<CIR> Afilmemulsionwithsensitivityfromgreenthroughinfrared.Thisemulsionisincommonuse,inpartduetoitssensitivitytodifferentcharacteristicsoflivevegetation. Command Aninstructionsentfromthekeyboardorothercontroldevicetoexecuteacomputerprogram. Commandlanguage AnEnglish-likelanguageforsendingcommandsforcomplicatedprogramsequencestothecomputer. Compiler Acomputerprogramthattranslatesahigh-levelprogramminglanguage,suchasFORTRANorPASCALintomachine-readablecode. Compositemap Asinglemapcreatedbyjoiningtogetherseveralseparatelydigitizedmaps. ComputerCompatibleTape<CCT> Magnetictapecontainingdataincomputer-readabledigitalformat.Themostcommonformatistermed9-track,forthenumberofparalleldatarecordingtracks;frequentlyusedlineardatadensitiesonthetracksare1600and6250bitsperinch. Computergraphics Ageneraltermembracinganycomputingactivitythatresultsingraphicimages. computingenvironment Thetotalrangeofhardwareandsoftwarefacilitiesprovidedbyagivenmakeofhostcomputeranditsoperatingsystem. Configuration Aparticularcombinationofcomputerhardwareandsoftwareforacertainclassofapplicationtasks. Console Adevicethatallowstheoperatortocommunicatewiththecomputer. Contour Alineconnectingpointsofequalelevation. ContourMap Atopographicmapthatportraysreliefbytheuseoflinesindicatingequalelevation.Suchiso-elevationlinesaretermedontourlines. Contrast thedifferencesinintensity<brightversusdark>ofdifferentpartsofanimage.thehighestpossiblecontrastisbetweenblackandwhite. Contrastenhancement Aprocedureforartificiallyincreasingthecontrastinanimage,oftenusedtoimproveananalyst'sabilitytodiscernfeatures. Coordinate Asetofnumericalquantitiesthatdesignatepositioninagivenreferencesystem. Cross-hatching Thetechniqueofshadingareasonamapwihagivenpatternoflinesorsymbols. Cursor Avisiblesymbleguidedbythekeyboard,ajoystick,atrackingball,oradigitizer,usuallyintheformofacrossorablinkingsymbol,thatindicatesapositiononaCRT. Database Acollectionofinterrelatedinformation,usuallystoredonsomeformofmass-storagesystemsuchasmagnetictapeordisk.AGISdatabaseincludesdataaboutghepositionandtheattributesofgeographicalfeaturesthathavebeencodedaspoints,lines,areas,pixelsorgridcells. Databasemanagementsystems<DBMS> Asetofcomputerprogramsfororganizingtheinformationinadatabase.Typically,aDBMScontainsroutinesfordatainput,verification,storage,retrieval,andcombination. Datalink Thecommunicationlinesandrelatedhardwareandsoftwaresystemsneededtosenddatabetweentwoormorecomputersovertelephonelines,opticalfibres,satellitenetworks,orcables. Dataset Acollectionofsimilarlyformattedrecordshavinglikeinformation<fromoneormoredatasources>. DatasetGranule asegmentofadataset,suchasasingleimage,oroneorseveralrecordsinsomefixedtimeincrement,orfilesoneachofseveraltapes.Usuallyconsideredthesmallestelementofinformationofvaluetoauser. DataSystem Acompositeofcapabilitiesformanagingdata,combiningfunctionsformaintainingadatacirectory,catalog,andinventory,aswelasaccessingdata. Debug Toremoveerrorsfromaprogramorfromhardware. Debugger Aprogramthathelpsaprogrammertoremoveprogrammingerrors. DefenseMappingAgency<DMA> AnagencyoftheU.S.Departmentofdefense. Device Apieceofequipmentexternaltothecomputerdesignedforaspecificfunctionsuchasdatainput,datastorage,ordataoutput. Digital Theabilitytorepresentdataindiscrete,quantizedunitsordigits. Digitalcomputer Anelectroniccalculatingdevicethatoperatesondiscretevariablerepresentations,ratherthanwithcontinuousoranalogvalues<comparewith"analogcomputer">. Digitalelevationmodel<DEM> Aquantiativemodeloflandformindigitalform.Alsodigitalterrainmodel<DTM>. DigitalLineGraph<DLG> AvectordatatypeproducedbytheU.S.geologicalSurvey. DigitalNumber<DN> Inremotesensing,thenumericalvalueofaspecificpixel. DigitaltoAnalogConverter<D/A> Adeviceusedtoconvertdigitalcomputervaluestoanalogvoltages.Foundincomputerdisplaysystems,wherethedigitalcomputervaluesareconvertedtoanalogsignalstomanipulatetheelectronbeaminavideodisplay. Digitize<noun> ApairofXYcoordinates;<verb>toencodemapcoordinatesindigitalform. Digitizer Adeviceforenteringthespatialcoordinatesofmappedfeaturesfromamapordocumenttothecomputer.SeealsoCursor,Puck,Mouse. Directory Acollectionofhigh-levelinformationaboutwholedatasets,forexample,adirectorycouldconsistofdatasetname,locationwhereitisstored,andsourcesoffurtherinformation. Disk Astoragemediumconsistingofaspinningdiskcoatedwithmagneticmaterialforrecordingdigitalinformation. Diskette Acheap,lowcapacitystoragemedium,usuallymeasuring3.5,5.25or8in.indiameter.Muchusedinmicrocomputers;alsoknownasa'floppydisk'. Dirichlettesselation Theprocessofsplittingupastudyareasuchthatallpointsinthesampleareaaregroupedintotilesaccordingtotheminimumdistancebetweenthemandapreviouslysampledpoint.alsoknownasThiessenorVoronoipolygons. Distributedprocessing Theplacementofhardwareprocessorswhereneeded,insteadofconcentratingallcomputingpowerinalargecentralCPU. Dot-matrixplotter Aplotterofwhichtheprintingheadconsistsofmany,closelyspaced<100-400perinch>wirepointsthatcanwritedotsonthepapertomakeamap.Alsoknownasanelectrostaticplotterormatrixplotter. Doubleprecision Typicallyreferstotheuse<in32-bitwordcomputers>ofadoublewordof64bitstorepresentrealnumbersto,inthiscase,aprecisionofapproximately16significantfigures. Drumplotter AdeviceforplottingmapsinwhichtheY=axismovementsaregovernedbytherotationofthedrum. Drumscanner Adeviceforconvertingmapstodigitalformautomatically. DualIndependentMapEncoding<DIME> Aformofectordatastructure. Easement Arestrictiononlanduse.forexample,aneasementmayprohibitalandownerfromconstructionthatwouldpreventemergencyvehiclesfromgainingaccesstotheproperty. Edit Toremoveerrorsfrom,ortomodifyacomputerfileofaprogram,adigitizedmaporafilecontainingattributedata. ElectromagneticRadiation Energypropagatingthroughspaceormatterintheformofwavesofinteractingelectricandmagneticfields.Radiowavesandlightareexamplesofelectromagneticradiation. ElectromagneticSpectrum Therangeofwavelengthsofknownelectromagneticradiations,includingultravioletradiation,visibleradiation,infraredradiation,andmicrowaves. Electrostaticplotter SeeDot-matixplotter. Element Afundamentalgeographicalunitofinformation,suchasapoint,line,area,orpixel.Mayalsobeknownasan'entity'. EndofFile<EOF> Aspecificcomputercodeusedtoindicatetheendofadataset. Extrapolation Theactofextendingtheresultsofspatialsamplingtopointsoutsidetheareasurveyed-notrecommended. FalseColorComposite Animageformedbyassigningcolorsarbitrarilytotwoormoreblack-and-whiteimagesofasinglescene.Theresultingimagepinpointsdifferenceandsimilaritiesbetweentheoriginalimages;theinputdatafrequentlycomefromethedifferentwavelengthbandsofamultispectralsensor. FieldofView<FOV> Thesolidanglethroughwhichaninstrumentissensitivetoradiation. File Acollectionofrelatedinformationinacomputerthatcanbeaccessedbyauniquename.Filesmaybestoredontapesordisks. Filter Inrastergraphics,amathematicalydefinedoperationforremovinglong-range<high-pass>orshortrange<low-pass>variation.Usedforremovingunwantedcomponentsfromasignalorspatialpattern. Floppydisk Seediskette. Flathedplotter AdevicefordrawingmapswherebytheinformationisdrawnbytheplottingheadbeingmovedinboththeXandYdirectionsoveraflat,fixedsurface.Drawswithapen,lightbeam,orscribingdevice. Floatingpoint Atechniqueforrepresentingnumberswithoutusingafixed-positiondecimalpointinordertoimprovethecalculatingcapabilityoftheCPUforarithmeticwithrealnumbers. Floating-pointboard AprintedcircuitboardplacedintheCPUinordertospeeduparithmeticoperationsforrealnumbers.<Thealternativeistousespecialsoftware,whichisusuallymuchslower.> Font Symbolismusedfordrawingalineorrepresentingtypefacesusedfordisplayingtext. Footprint Theareaonthesurfacebeinginvestigatedbyaremotesensingdevice; Format Thewayinwhichdataaresystematicallyarrangedfortransmissionbetweencomputers,orbetweenacomputerandadevice.Standardformatsystemsareusedformanypurposes. FORTRAN<FORmulaTRANslation> Ahigh-levelprogramminglanguage,muchusedincomputergraphicsandCAD/CAM.Recentimprovements,embodiedinFORTRAN77,havemadestructuredprogrammingandinteractivedatainputmucheasier. Fourieranalysis Amethodofdissociatingtimeseriesorspatialdataintosetsofsineandcosinewaves. Fractal Anobjecthavingafractionaldimension;onewhichhasvariationthatsself-similaratallscales,inwhichthefinallevelofdetailisneverreachedandnevercanbereachedbyincreasingthescaleatwhichobservationsaremade. Gap Thedistancebetweentwographicentities<usuallylines>onadigitizedmap.Gapsmayarisethrougherrorsmadewhiledigitizingorscanningthelinesonamap. Geocoding Theactivityofdefiningthepositionofgeographicalobjectsrelativetoastandardreferencegrid. GeographicInformationSystem<GIS> Thecompletesequenceofcomponentsforacquiring,processing,storagingandmanagingspatialdata. GeostationarySatellite Asatelliteorbitingabovetheearth'sequatoratanaltitudeofapproxium36000km,suchthatitsperiodofrevolutionabouttheEarthmatchestheEarth'srotationalperiod.thus,thesatellitecontinuouslyviewsthesameportionoftheEarth'ssurface.Alsocalledgeosynchronoussatellite. GIMMS GeographicInformationManipulationandMappingSystems.Awell-known,low-costpolygonmappingGIS. GKS GraphicskernalSystem.Asetofsoftwareprimitivesforallowingdevice-independentgraphicsprogramming. Graphicstablet Asmalldigitizer<usuallymeasuring11×11in.>usedforinteractiveworkwithaGISorCAD/CAMsystem. Greyscales Levelsofbrightness<ordarkness>fordisplayinginformationonmonochromedisplaydevices. Grid 1.AnetworkofuniformlyspacedpointsorlinesontheCRTforlocatingpositions. 2.Asetofregularlyspacedsamplepoints. 3.Incartography,anexactsetofreferencelinesovertheearth'ssurface. 4.Inutilitymapping,thedistributionnetworkoftheutilityresources,e.g.electricityortelephonelines. Gridmap Amapinwhichtheinformationiscarriedintheformofgridcells.SeeRaste. GroundTruth Informationobtainedontheground,atthesametimearemotesensingisacquiringdatfromthesamelocation.Groundtruthisnormallycon****themostaccurateavailable,andisusedtointerpretandcalibrateremotesensedobservations. Hard-copy AcopyonpaperofagraphicsormapimageoriginallydisplayedonaCRT. Hardware ThephysicalcomponentsofaGIS-thecomputer,plotters,printers,CRTs,andsoon. Hiddenlineremoval Atechniqueinthree-dimensionalperspectivegraphicsforsuppressingtheappearanceoflinesthatwouldordinarilybeobscuredfromview. Hierarchicaldatabasestructure Amethodofarrangingcomputerfilesorotherinformationsothattheunitsofdatastorageareconnectedbyahierarchicallydefinedpathway.Fromabovetobelow,relationsareone-to-many. High-DensityDigitalTape<HDDT> Ananalogsystemforstoringveryhighratedatathatisnotdirectlycompatiablewithgeneral-purposecomputersystems. High-levellanguage Acomputerprogramminglanguageusingcommandstatements,symbolsandwordsthatresembleEnglish-languagestatements.ExamplesareFORTRAN,PASCAL,C,PL/1,COBOL,BASIC. Histogram Adiagramshowingthenumberofsamplesthatfallineachcontiguouslydefinedsizeclassoftheattributestudied. Hostcomputer Theprimary,orcontrollingcomputerinadatanetwork. HotineObliqueMercator<HOM> Amapprojection,oftenusedfordatafromspacecraftplatforms. HumanEngineering Thedesignandimplementationofautomatedandmechanicalsystems,takinghumanpsychologicalconcernsintoconsideration. Hypsometry Themeasurementoftheelevationoftheearth'ssurfacewithrespecttosealevel. Image Atwo-dimensionaldatarepresentation,Examplesincludeaphotograph,amultispectralimagingsensor'sdataoutput,andtheprocessedresultofanaeromagneticsurvey. ImageClassification Analysisofdigitalimagevalues,includingoneormorespatial,temporal,andspectralbandrelationships,toobtaincategoriesofinformationaboutspecificfeatures. Information Datathathasbeenprocessedforaparticularuse. InitialGraphicsExchangeSpecification<IGES> Aninterimstandardformatforexchanginggraphicsdatabetweencomputersystems. Input <Noun>thedataenteredtoacomputersystem.<Verb>theprocessofenteringdata. InstantaneousFieldofView<IFOV> Forasensingdevice,theareacoveredatasinglemoment,describedeitherattheanglethroughwhichthesensorgathersradiation,ortheareaonthegroundataspecifiedaltitude. Integer Anumberwithoutadecimalcompoent;ameansofhandingsuchnumbersinthecomputerwhichrequireslessspaceandproceedsmorequicklythanwithnumbershavinginformationafterthedecimalpoint. IntegratedGeographicInformatinSystem<IGIS> Ageographicinformationsystemthatincludesfacilitiesforworkingwithremotelysenseddata. Interactive AGISsysteminwhichtheoperatorcaninitiateormodifyprogramexecutionviaaninputdeviceandcanreceiveinformationfromthecomputerabouttheprogressofthejob. Interactivegraphicssystem Acomputersystemconsistingofacentralcomputer<usuallyaminicomputer>andanumberofworkstationsatwhichanoperatorcandraftmapsanddrawingsinteractively. InteractiveProcessing Operationofacomputersystemthroughcontinual,instantaneouscommunicationbetweenmanandmachine.Incontrasttobatchprocessin. Interface Ahardwareandsoftwarelinkthatallowstwocomputersystems,oracomputeranditsperipheralstobeconnectedtogetherfordatacommunication. Interpolate Toestimatethevalueofanattributeatanunsampledpointfrommeasurementsmadeatsurroudingsites. Interval 1.Thetimebetweentwoevents. 2.Asameasurementscale,variablesinwhichthedistancesbetweendatavaluesaremeaningfulbutbasedonanarbitrarystartingpoint<e.g.,CelsiusandFahrenheittemperaturescales>. Inter-recordGap<IRG> Theeffectivelyemptydistancebetweendatarecordsonmagnetictapestorage. Inventory Acollectionofinformationaboutthegranulesofadataset. Isoplethmap<Isoline> Amapdisplayingthedistributionofanattributeintermsoflinesconnectingpointsofequalvalue;Seecontour,contrastwithChoroplethmap. Jaggies Jargontermforcurvdlinesthathaveasteppedorsaw-toothappearanceonadisplaydevice. Join <Verb>toconnecttwoormoreseparatelydigitizedmaps;<Noun>thejunctionbetweentwosuchmaps,sometimesvisibleasaresultofimperfectionsinthedata. Joystick Aband-controlledleverforcontrollingthemovementsofthecursoronagraphicsCRT. Justification<right,left,orcentre> Therelativepositionofatextstringorsymbolonthemaptothelocationatwhichithasbeendigitized. Keyfile InsomeCAD/CAMsystems,afilecontainingthecodesdefiningtheoperationofcertainkeyboardfunctions,ormenucommands.InDBMS,afileontaininginformationaboutsearchpathsorindexesusedtoaccessdata. Keyboard Adevicefortypingalphanumericcharactersintothecomputer.Thearrangementofthekeysresemblesthatofatypewriter,butoftenhasmorecapabilities. Kriging Name<afterD.G.Krige>foraninterpolationtechniqueusinginformationaboutthestochasticaspectsofspatialvariation. LandCover Thematerialscoveringalandsurface,suchasvegetation,exposedsoils,andforth. LANDSAT ThegenericnameforaseriesofearthresourcescanningsatelliteslaunchedbytheUnitedStatesofAmerica. LandUse Human-imposedfunctionsofalandarea. Laserplotter Aplotterinwhichtheinformationiswrittenontolight-sensitivematerialusingalaser. Latitude Asystemforindicatinglocationnorthorsouthoftheequator,basedontheminimumanglesubtendedbetweenthelocationinqueston,theEarth'scenter,andtheequator. Layer Alogicalseparationofmappedinformationaccordingtotheme.ManygeographicalinformationsystemsandCAD/CAMsystemsallowtheusertochooseandworkonasinglelayeroranycombinationoflayersatatime. Legend Thepartofthedrawnmapexplainingthemeaningofthesymbolsusedtocodethedepictedgeoraphicalelements. Library Acollectionofstandard,oftenusedcomputersubroutines,orsymbolsindigitalform. LIDAR Theabbreviationforlightdetectionandranging.Aremotesensingsystem,usingtheinteractionoflightpulseswithmaterialsatadistance.Usedfordeterminingatmosphericconstituentsandrangeofdistantsurfaces,amongotherthings. Light-pen Ahand-heldphotosensitiveinteractivedeviceforidentifyingelementsdisplayedonarefreshedCRTscreen. Line Oneofthebasicgeographicalelements,definedbyatleasttwopairsofXYcoordinates. Linefollower Asemi-automaticdeviceinwhichalaserbeamisusedtotraceoutlinesfromasourcemapandconvertthemtodigitalform. Lineprinter Aprinterthatprintsalineofcharactersatatime. Longitude Anarbitrarysystemforindicationlocationeastorwest,basedontheanguldistancearoundtheEarth'ssurfacefromthehalfofagreatcirclepassingbetweenthenorthandsouthpolesandthroughGreenwich,Enland. Look-uptable Anarrayofdatavaluesthatcanbequicklyaccessedbyacomputerprogramto