12大地测量学概念

Unit12GeodesyConcepts（大地丈量学观点）Asweknow,surveyingisdividedintotwomajorcategories:geodeticsurveyingandplanesurveying.（我们知道，丈量分为两个主要范围【

category种类、范围】：大地丈量和平面丈量）Geodeticsurveyingtakesintoaccountthetrueshapeoftheearthwhereasplanesurveyingtreatstheearthasaflatsurface（.大地丈量要考虑【

takeintoaccount考虑】地球的真切形状，而【whereas但是、但是】平面丈量把地球视为【treat】一个平面）ThesubjectofthistextaimsatthestudyofthesizeandshapeoftheearthwhichreferstoGeodesy（.这篇文章的主题【

subject】针对【aimat】的就是波及【referto】大地丈量学的地球的大小和形状的研究）Theexpression“thesizeandshapeof

theearth

”hasvariousmeaningsin

geodesyaccordingtothewayitisusedandtheprecisionwithwhichtheearth

’bedefined（.依据【accordingto】定义地球大小和形状所使用的方法和精度，“地球的大小和形状”的表达在大地丈量学中有各种各种的【

various】含义）Theactualtopographicsurfaceismostapparentwithitsvarietyoflandformsandwaterareas（.实质的地表【topographic地形的、地形学的surface表面这里直接译为地表】大多表现为地形【landform】和水域的多样性【variety】）【ismostapparentwith副词短语做表语】Thisis,infact,thesurfaceonwhichactualearthmeasurementsaremade.（事实上【infact】，事实上，这就是所做的地球实质表面丈量。）Itisnotsuitable,however,forexactmathematicalcomputationsbecausetheformulaswhichwouldberequiredtotaketheirregularitiesintoaccountwouldnecessitateaprohibitiveamountofcomputations（.但是，对于精准的【exact】数学计算这其实不适合，因为需要考虑到【takeintoaccount】不规则【irregularity】的公式【formula】将需要necessitate需要、被需要】大批的【prohibitive特别高的、受抑制的、严禁的】计算）Theconceptofgeodesyshouldbementionedfirst（.第一应当说一下【mention说起】大地丈量学的观点）FromtheConciseOxfordDictionary:geodesy.n.Thebranchofmathematicsdealingwiththefiguresandareasoftheearthorlargeportionsofit（.简洁【Concise简洁的】牛津词典：大地丈量学n.名词.数学的一个分支，用来办理地球或其一大多数【portion一部分】的形状和地区）EncyclopediaofScienceandTechnology,2001edition,AcademicPress,2000:Geodesyisascience,theoldestearth(geo-)science,infact.（科学与技术百科全书【Encyclopedia百科全书】，2001版，学术第一版社【AcademicPress】，2000：大地丈量学是一门科学，事实上，是最古老的地球科学）Itwasbornoffearandcuriosity,drivenbyatopredictnaturalhappeningsandcallsfortheunderstandingofthesehappenings（.受预知【predict】自然事件【现象】和要求理解这些事件【现象】的梦想所驱动，由惧怕和气奇而生。

）Theclassicaldefinition,accordingtooneofthe

“fathersofgeodesy

”thescienceofmeasuringandportrayingtheearth

’ssurface

”（[Helmert,经典188【classical经典的、古典的】定义，依据“大地丈量学之父”的此中一位的说法：“大地丈量学是丈量和描述【

portray】地球表面的科学”

[Helmert,1880,p.3]

）【Helmert德国人赫尔默特（

，1843—1917

）开创海上重力测定】Nowadays,weunderstandthescopeofgeodesytobesomewhatwider（.现在，我们理解大地丈量学的范围【scope范围】就有些【somewhat有些】宽了）Itiscapturedbythefollowingdefinition[VanicekandKrakiwsky,1986,p.45]:isthedisciplinethatdealswiththemeasurementandrepresentationoftheearth,includingitsgravityfield,inathree-dimensionaltimevaryingspace.（”从以下定义就能够得悉【capture俘获、获取，这里指可由下边的定义所认识】[VanicekandKrakiwsky,1986,45]：“大地丈量学是波及【dealwith】，在一个三维的时空中，丈量和描述包含重力场在内的地球的一门学科【discipline学科】）According

totheclassicaldefinition

of

Helmert,

geodesyis

the

“scienceof

themeasurementandmappingoftheearth

’ssurface（依据赫”尔.默特的经典定义，大地测量学是“丈量和绘制地球表面的科学”）Thisdefinitionhastothisdayretaineditsvalidity;itincludesthedeterminationoftheearth’sexternalgravityfield,aswellasthesurfaceoftheocean（floor这个.定义时到现在天tothisday到现在】还保存着【retain保存】它的有效性【validity有效性、正确性】；它包含地球的外面【external外面、外面的】重力场、也包含了大海底部的表面的测定【determination这里翻译成测定】。）Withthisdefinition,whichastobeextendedtoincludetemporalvariationsoftheearthanditsgravityfield,geodesymaybeincludedinthegeosciences,andalsoinengineeringsciences,e.g.,NationalAcademyofSciences(1978)（.依据这个定义——对于【asto】被扩展包含时间变量【temporal时间的；variation变量】的地球和它的重力场，大地丈量学能够被包含进地球科学、也能够被包含进工程学，比如【e.g.注意读音i:dgi】，国家科学院（1978））So,we’velearnedthatGeodesyisthedisciplinethatdealswiththemeasurementandrepresentationoftheearth,itsgravityfieldandgeodynamicphenomena(polarmotion,earthtides,andcrustalmotion)inthree-dimensionaltimevaryingspace（.这样【so】，我们已经知道了大地丈量学是对于在三维时空中丈量和表述地球自己、它的重力场和地球动力学【geodynamic】现象（极移【motion挪动】，固体潮，和地壳【crustal】运动）的学科【discipline】）Geodesyisprimarilyconcernedwithpositioningandthegravityfieldandgeometricalaspectsoftheirtemporalvariations（.大地丈量学主要波及它们的时间变量【temporal时间的；variation变量】的地点、重力场和几何表面）Triggeredbythedevelopmentofspaceexploration,geodesyturnedincollaborationwithothersciencestowardthedeterminationofthesurfacesofothercelestialbodies(moon,otherplanets).（因为空间探究的发展的触发【Trigger】，大地丈量学转而与其余科学合作【incollaborationwith与合作】，来【toward为了、向】确立其余天体【celestialbody】（月球、其余行星）的表面）Thecorrespondingdisciplinesarecalledselenodesyandplanetarygeodesy（.其相应的学科被称为月面丈量学【selenodesy】和行星大地丈量学【planetarygeodesy】）Geodesymaybedividedintothreebasicsubdisciplines:geometricgeodesy,physicalgeodesy,andspacegeodesy（.大地丈量学能够分红三个基安分支：几何大地丈量学、物理大地丈量学、和空间大地丈量学）Geometricgeodesy(alsocalledastro-geodesy)concernswithdeterminationofthesizeandshapeoftheearthaswellasthepositionontheearthsurface（.几何大地丈量学（也称为天文大地丈量学【astro-geodesy】）波及确立地球大小和形状，还有地球表面上的地点确实定。）Forthepurposeofdeducingthesizeandshapeoftheearthandthepreciselocationofspecificpositionsontheearth’ssurface,geometricgeodesyconsidersthegeoidththeuseofastrogeodeticmethods（.为了【Forthepurposeof】推出【deduce】地球的大小和形状，还有地球表面上的明确【specific明确的】地点的精准定位【location地点、点位n.】，几何大地丈量学考虑的是大地水平面，经过几何大地丈量的方法）Thisaspectofthescienceisinvolvedwiththebasicprinciplesoftheestablishmentofthenationalgeodeticnetworkswhichincludebothhorizontalandverticalcontrolsandstrictlygeometricalrelationshipsmeasuredinvariousways:astronomicpositioning,triangulation,trilateration,andtraversearefourtraditionalsurveyingtechniquesingeneralusefordeterminingtheexactpositionsofpointsontheearthsurface（.该学科【’thesscience】的这个方面【aspect】波及成立国家大地网的基来源理【basicprinciple】，包含水平易高程控制，并以不一样方式【invariousways】严格测定几何关系：天订婚位、三角丈量、三边丈量、导线丈量是在确立地表点精准地点时往常的四种传统丈量技术）Inrecentyears,moderntechnologicaldevelopmentshaveaddedseveralnewmethodsutilizingartificialearthsatellites.（最近几年来，现代科技的发展增添了几种利用【utilize利用】人造地球卫星【artificial人造的】的新方法。）Othermethodsrelevanttogeodeticsurveyingarebeingdeveloped（.其余有关的【relevant有关的】大地丈量方法也获取发展）Physicalgeodesyutilizesmeasurementsandcharacteristicsoftheearthtyfieldas’sgravwellastheoriesregardingthisfieldtodeducetheshapeofthegeoidandincombinationwitharcmeasurements,theearth（物’理s大size地测.量学利用【utilize利用】丈量和地球重力场特点还有对于重力场的理论，来推出大地水平面的形状；与弧度丈量【arcmeasurement】相联合【incombinationwith与联合】推出地球的大小）Withsufficientinformationregardingtheearth

’sgravityfield,itispossibletodgeoidalundulations,gravimetricdeflections,andtheearth

（利用波及’地sflattening球重.力场充分的【sufficient】信息【regarding波及，介词prep.】，就能够确立大地水平面颠簸【undulations】、重力误差【gravimetricdeflection】、和地球扁率）Spacegeodesy(Satellitegeodesy)usessatellitesforgeodeticpurposeswhichwereadvocatedandpublishedasearlyas1956（.空间大地丈量学（卫星大地丈量学）把卫星用于大地丈量的目的，早在【asearlyas早在】1956年就被提出【advocate】和发布【publish发布、第一版】了）Withtheconstantgrowthofspacetechnology,thedevelopmentofelectronicdistancemeasuringdevices,andtheperfectionofelectronicdataprocessingequipment,satellitesspecificallyequippedforgeodeticpurposeshavebeendeveloped,launched,observedandthedatautilized.（跟着空间技术的不停发展，电子测距仪的发展，和电子数据办理electronicdataprocessing电子数据办理】装置的完美【perfection】，特为【specifically特别地】大地丈量目的装备的卫星已经被发展、发射、观察和数据利用了【或译为：已经发展、发射、观察并其数据已获取应用了】）Severalobservationalsystems,geodeticcameras,electronicrangingandDopplerSatelliteSurveysweredevelopedandimproved（.几种观察系统，大地丈量摄像机，电子测距和多普勒卫星丈量被发展和改良了）Someoftheareasofnewgeodeticdevelopmentsare:satellitelaserranging,lunarlaserranging,verylongbaselineinterferometry,satelliteradaraltimetry,theGlobalPositioning