摄影测量学毕设论文外文翻译翻译+原文.docx

摄影测量学毕设论文外文翻译翻译+原文.docx

《摄影测量学毕设论文外文翻译翻译+原文.docx》由会员分享，可在线阅读，更多相关《摄影测量学毕设论文外文翻译翻译+原文.docx（8页珍藏版）》请在冰豆网上搜索。

摄影测量学毕设论文外文翻译翻译+原文

Photogrammetry

TheprinciplesofphotogrametrycanbetracedbacktotheworksofLeonardodaVinciinthelatefifteenthcentury.Throughhisworkinthefieldsofgeometry,optics,mechanics,andgeophysiscs,daVincigraphicallyillustratedtheconceptsofaerodynamicsandopticalprojection.Itisnotuntilthemid1800sthatthefieldofphotogrammetrycameintoitsown,particularlywithintheEuropeancommunity.Thetermphotogrammetrywasfirstcoinedin1855bytheEuropeangeographerKersten,andwasincommonusethroughoutEuropeby1900.Theterm,however,didnotwinwideacceptanceintheUnitedStatesuntil1934.Inthatyear,theAmericanSocietyofPhotogrammetry（ASP）wasfounded.

TypesofPhotogrammetryTheASPcurrentlyconsiderphotogrammetrytobetheart,science,andtechnologyofsurveyingandmeasuringbyphotographicandotherenergy-emittingprocesses.Theprocedureisextensivelyusedintopographicmapping,andcanbeappliedfromthegroundaswellasintheair.Aerialphotogrammetry,though,istheproceduremostcommonlyusedinmapping.Ithasallbuteliminatedtheneedforextensivefieldsurveys.Ground,orterrestrial,photogrammetryisusedonlyasasupplementandcomplementtotheaerialprocess,orinareaswithunusualphysicalcharacteristics.

Likeotherprofessionaldisciplines,photogrammetryconsistsofavarietyofspecialtyareas.Forexample,therearethetwobroadareasifterrestrial（ground）andaerial（air）photogrammetry.Otherspecialtyareasofphotogrammetryaredefinedastothetechnologyorenergyemittingprocessused.Someofthetypesofphotogrammetryusedinthemappingandtopographicfieldarediscussedhere.

Radargrammetryistheuseofradarasameasuringdevicetodescribethephysicalcharacteristicofanareaoftheearth’ssurface.X-rayphotogrammetryemployX-raytocollectsurveyingdata,andtheuseofmotionpicturesforsurveyingiscalledcinephotogrammetry.

Hologrammetryistheuseofholographsimagesprojectedbytheuseofcoherentlightsystemssuchaslaserstomeasuresurfacecharacteristics.Inmonoscopicphotogrammetry,singleimagesorphotographsareuseorsurveyingpurposes.Finallythereisspaceorsatellitephotogrammetry,inwhichspacecraftorsatellitesareutilizedasutilizedasaplatformfortakingsurfacemeasurements.Thistypeisalsoreferredtoasextraterrestrialphotogrammetry.

AerialPhotography:

Theaerialphotographisperhapsthemostfamiliarproductofthephotogrammetryfield.Itapplicationinthemappingandtopographicdadacollectionprocesscombinestheuseofscientificandartisticproceduresandtechniques.Aerialphotogrammetry,then,istheuseofphotographicimagestakenfromanairbornebaseforsurveyingpurpose.

Thesuccessandaccuracyofanaerialphotographymissionisdependentuponanumberofimportantfactors,includingthefollowing:

1.Theuseofcorrectphotographicequipment,lenses,andsupplies;

2.Appropriatecorrectphotographicmaterials,suchasfilm,printandduplicationmaterials,reflectionprintmaterials,andplates;

3.Thephotographicteam（pilot,photographer,andfilmprocessor）;

4.Weatherconditions;

5.Thepositionofthesunwhenthephotographsaretaken.

ClassificationsofAerialPhotographyAerialphotographyisacomplexanddynamicprofession,asisthephotogrammetricfieldingeneral.Aerialphotographyrequiresavastarrayofequipment,technologies,andprocedures.Therefore,toclassifythevarioustypesofaerialphotographsusedinthemappingandtopographicfield,TheASPhasidentifiedfourcriteria:

theorientationofthecameraaxis,thetenssystems,thespectralrange,andthemodeofscanningthesecriteriaarediscussedinthissection.

OrientationofCameraAxisThisreferstotheangleatwhichthecameraisintentionallypositionedatthetimeofthephotograph.Adshowninfig.23-1,thesearetwoorientationsofaxis,usedinaerialphotography.Thesearetheverticalorientationaxisandtheobliqueorientationaxis.

Withaverticalorientationaxis,thephotographistakenwhenthecameraisintentionallypositionedasnearlyvertical-orascloseto90°totheearth’ssurface-aspossible.Becauseoftheearth’scurvatureandaeronauticalfactors,itisimpossibletoobtainatruetheoreticalverticalpicture（hencethequalifier“asnearlyverticalaspossible”）.Forpracticalmappingpurposes,however,the“nearvertical”ismorethansufficient.

Theverticalorientationaxisisthemostcommontypeofaerialphotographusedinmapping.Thistypeofphotographcambeeasilyconvertedintomapdrawings:

itfivesasenseofanexfistingmaporchart.Thethreemajoradvantagesofusingtheverticalorientationaxisarethatmeasurementscanbeeasilytakenoffthephotographandtransferred,surfaceobjectsandlandmarkscanbeeasilyidentifies,andtheamountofhiddenground（areasnotobservableinthephotograph）willbeminimal.

Obliqueorientationaxisphotographsareimagesintentionallyregisteredoffvertical,andintheoblique,technically,thismeansthatthecameralensangleisaimedbetweentruehorizontalandvertical.Thesephotographscanbefurthersubclassifiedintohighobliqueandlowoblique.highobliquephotographspertaintotheopticalaxisofthecamerabeingatahighangletothevertical,whilelow-obliquephotographshavetheopticalaxisofthecameraatalowangletothevertical.

Obliquephotographshavealimitedapplicationformapping.Theyareonlyofpracticaluseinsituationsrequiringsmall-scaledrawings.Thetwoadvantagesoftheobliquephotographsarethattheyprovideastereoscopicorthree-dimensionalperceptionofthephotographedarea,andtheycanprovidealargerareacoveragethanisprovidedbyverticalphotographs.thereare,however,threesignificantdisadvantagestousingthesephotographsformapandtopographicdrawings.Fist,thereisalossofimageryandresolution.Second,thescaleconstantlyreducesasoneobservesimagesawayfromthecamera.Thirddisadvantageisthathighlyskilledpersonnelandspecializedequipmentareneededtogenerateanaccurateandusefulproduct,resultinginhighercost.

LensSystemsTheseareclassifiedbythenumberandconfigurationofthecameralensesusedforaerialphotographs.Withinthisframework,alllenssystems,andthemultiplelenssystems.

Thesingle-lenssystemisthemostpopularandfrequentlyusedsysteminaerialphotography.Itisapplicableforeitherverticalorobliquephotographs.Thesingle-lenssystemusuallyemploysa153millimeter（mm）focallengthwitha228×228mmformat,whileusingonlyonelenspershot.Bycomparison,superwide-anglelenscamerasareseldomused.Ifused,however,itisforphotographicmissionsoverlow-reliefterrain.

Multiple-lenssystemsconsistoftwoormorelenses.Thesesystemscanbesubclassifiedbythetypeofmountingused.Thefistmountingiswherethelensesareseparatelymountingindifferentcamerasandtheshuttersaresynchronizedforsimultaneousexposures.Ineachcase,thelensesarefixedatdifferentopticalaxessothatthephotographscanbeusedonastereoscope.Theaccuracy,andusefulnessofphotographstakenwithamultiple-lenssystemaredependentuponthecareandaccuracy,ofthecalibrationandretentionoftheaxisangles.

Anothertermusedforthemultiple-lenssystemismultispectralsystemsconsistoftwoormorecameras,simultaneousexposuresofanareaofland,andthechoiceofdifferentfilmsand/orfiltercombinations.

SpectralRangeThiscriterionreferstotheentirerangeoflightonthespectrum.Thevastmajority,ofaerialphotographislimitedtotherangeofthespectrumthatcanbeobservedbythehumaneye.Thisiscalledtheopticalrange.insomesituations,aerialphotographsareusedtorecordimageswithintheinfraredrange.

Spectralismeasuredintermsofmicrometers（um）.AsshowninFig.23-2,theopticalrangeisfrom0.4umto0.8umum,whiletheinfraredrangestartsat0.8um.Withtheuseofphotographicfilmcapableofrecordingopticalrangeimage,itisalsopossibletorecordsomeinfraredimagesatthelowerendofthescale（i.e.,0.8umand0.9um）.Photographyfurtherintotheinfraredrangerequirestheuseofspecialfilmandprocedures.Becauseinfraredisusedtophotographtemperaturedifference,itisalsoreferredtoasthermalphotography.

ModeofScanningThisisthelastcriterionusedinclassifyingaerialphotographs.Therearethreescanningmodesusedinaerialphotography:

thesingleframe,panoramicandcontinuousstrip.Inthissense,scanningreferstohowthecameralensfunctionsduringthephotographicprocess.

Ofthethreescanningmodes,thesingle-framecamera,theentireframe（format）isexposedthroughalensthatisfixedinrelationtothefocalplane.Thesecamerasaretheeasiesttouseandtheleastexpensive.Theyalsoprovidethemostaccuratedatatotransferontomapsandtopographicdrawings.Thereare,however,twodisadvantagestosingleframephotographs.First,theseisaresolutionasonemovesawayfromthecenterofthephotography.

Theproblemsassociatedwithsingleframephotographscanbesolvedwiththeuseofpanoramicorcontinuous-stripcameras.Panoramicphotographycombinesahighresolutionatthecenterofthepictureoverthetotalanglescanned,whichinsomecasescanbefromhorizontohorizon.Panoramicphotographyisaccomplishedbyusingnarrowangles,fastlenssystems,byscanningthelenssystemthoughlargeanglesacrosstheflightpath,andbyusingnormal-widthfilmandadvancingitparalleltothescanningdirectionatgroundspeed.

Continuous-stripphotographyeliminatestheneedforaconventionalshuttersystem.Theimagesareexposedonthefilmasthefilm