测绘工程专业英语课文全部翻译

Section2TheReliabilityofaSurveyandErrors测量误差可靠性Sinceeverytechniqueofmeasurementissubjecttounavoidableerror,surveyorsmustbeawareofallsourcesandtypesoferrorandhowtheycombine.Iftheaccuracyofameasurementisdefinedasthenearnessofthatvaluetoitstruevalue(aquantitywecanneverknow)thenasurveyormustensurethatthetechniqueshechooseswillproducearesultthatissufficientlyaccurate.Hemustknow,therefore,howaccurateheneedstobe,howtoachievethisaccuracyandhowtocheckthattherequiredaccuracyhasbeenachieved.因为每个测量技术是不可防止误差，测量员必须知道全部误差起源和类型，以及它们是怎样结合。假如测量准确性，其真正值（我们能够永远不知道数量）靠近程度，该值被定义为，然后测量员必须确保他选择技术将产生一个结果，是足够精准。所以，他必须知道他需要精度怎样，怎样实现这一目标准确性和怎样检验所要求精度已经达成。AccuracyrequiredWhensurveyingtoproduceaplan,theaccuracyrequiredisdefinedbythescaleoftheplot,sincethereshouldbenoplottableerrorinthesurveydata.Agooddraughtsmancanplotalengthtowithin0.25mmandso,ifaplanofanareaisrequiredatascaleof1/1000,i.e.,1mmontheplanrepresents1montheground,thesmallestplottabledistanceis0.25m.Thus,forasurveyat1/1000scale,allthemeasurementsmustbetakensuchthattherelativepositionsofanypointwithrespecttoanyothermustbedeterminedto0.25morbetter.当测量一个平面时,精度通常是依照展图百分比决定，因为在绘图中不能有测量误差。一个好绘图员能够在大约0.25毫米范围内画图，假如一个地域图纸百分比尺要求是1/1000，即1毫米图上距离代表1米实地距离，那么最小测距应该是0.25米。所以，对于1/1000百分比尺测量，全部测量必须确保任意一点与其余任一点相对位置不得大于0.25米。Thespecificationsofsurveysforotherpurposessuchasengineeringworksorpropertyboundarydefinitionmightwellbedeterminedbyengineeringtolerancesorlegalstandards.基于测量规范可能被用于其余目标，如工程测量或财产边界测量将由工程限差和正当基准决定。AchievingthespecificationToensurethatthespecificationisachievedtheequipmentandmethodsmustbechosensuchthat,notonlywilltheycollecttherightsortofdata,i.e.,thecorrectcombinationofanglesanddistances,butthatthedatawillbetotherequiredaccuracy.Thereareseveraltypesoferrorthatoccurandaknowledgeoftheirimportanceandcharacteristicsisessentialintheunderstandingofthelimitationsofthetechniquesofmeasurement.Thesalientfeatureswillbestatednowbutfurtherinformationisgiveninlaterchapters.为了确保测量符合规范，仪器和数据应按照以下要求进行，并不是只是得到正确数据，即更正角和边关系，从而得到数据满足精度要求。在测量中有几个类型误差，掌握它们主要性和特征对于了解测量技术限差是必不可少。本章主要讲解这些误差主要特征，后面章节将提供深入阐述。Mistakes粗差Blundersormistakesareofteninaccuratelyreferredtoasgrosserrors.Miscountingthenumberoftapelengthswhenmeasuringalongdistanceortransposingnumberswhenbookingaretwoverysimple,butalltoocommon,examplesofmistakes.Thesetypesofmistakescanoccuratanystageofasurvey,whenobserving,booking,computingorplotting,andtheywouldobviouslyhaveaverydamagingeffectontheresultsifleftuncorrected.However,byfollowingstrictlyawell-plannedobservingprocedureitispossibletoreducethenumberthatoccurandthenindependentchecksateachstageshouldshowupthosethathavebeenmade.Inpractice,noneshouldevergoundetectedanduncorrected.错误经常不准确了解为粗差。当测量很长一段距离时，读错尺读数或统计两个简单数时颠倒它们位置，这些都是很常见错误例子。这些类型误差能够发生在测量任何阶段，当观察，统计，计算和绘图，假如不纠正这些错误，他们在结果上显然有一个非常有害影响。不过，经过严格周详观察过程，可能杜绝这些错误产生，然后在每个阶段应独立检测能够是这些错误显现出来。在实践中，没有不可发觉和不可纠正粗差。Systematicerrors系统误差Systematicerrorsarisefromsourceswhichactinasimilarmanneronobservations.Themethodofmeasurement,theinstrumentsusedandthephysicalconditionsatthetimeofmeasurementmustallbeconsideredinthisrespect.Expansionofsteeltapes,frequencychangesinelectromagneticdistancemeasuring(EDM)instrumentsandcollimationinalevelarejustafewexamplesofpossiblesourcesofsystematicerrors.系统误差起源于以相同观察方式。测量时要考虑这些方面，测量方法、测量仪器和外界环境。钢尺膨胀，电磁测距仪频率改变和水准仪照准情况都是系统误差可能起源。Theseerrorsareofvitalimportanceinactivitieswhichconsistofaddingtogetherasuccessionofindividualobservations(seesectionsonlevelingandtraversing).Ifalltheindividualmeasurementscontainthesametypeofsystematicerror,whichbytheirnaturealwaysactinthesamedirection,thenthetotaleffectisthesumofthemall.这些误差在由一系列独立观察（参见水准测量和导线测量部分）累加在一起组成测量值中极为主要，假如全部独立测量包含相同类型系统误差，且这些系统误差总是表现出相同性质，那么总影响是全部这些总和。Itmustbeensuredthatmeasurementsareasaccurateasrequiredbyremovingtheeffectsofallfactorsthat,ifneglected,wouldresultinasignificanterror.Theerrorscausedbysomefactorscanbeeliminatedwiththecorrectobservingprocedureandotherscounteredbyapplyingcorrections.Systematicerrorsarenotrevealedbytakingthesamemeasurementagainwiththesameinstruments.Theonlywaytocheckadequatelyforsystematicerroristoremeasurethequantitybyanentirelydifferentmethodusingdifferentinstruments.经过消除全部原因影响确保精度满足要求。怎样忽略这些原因将会造成重大错误。经过正确观察程序以及纠正计算能够消除误差。经过一样仪器用一样方法测量是检测不出系统误差。唯一能充分检测系统误差就是重测这些量经过使用完全不一样测量方法和测量仪器。RandomerrorsRandomerrorsarereallyallthosediscrepanciesremainingoncetheblundersandsystematicerrorshavebeenremoved.Evenifaquantityismeasuredmanytimeswiththesameinstrumentinthesameway,andifallsourcesofsystematicerrorhavebeenremoved,itisstillhighlyunlikelythatallresultswillbeidentical.Thedifferences,causedmainlybylimitationsofinstrumentsandobservers,arerandomerrors.随机误差实际上是除去粗差和系统误差后。即使测定数量很数次以一样方式与相同仪器，和已被删除，假如全部系统误差起源，它依然是极不可能，全部结果将是相同。差异，主要仪器和观察员限制造成，是随机误差。Itisfoundinpracticethattheseerrors,althoughcalledrandom,havethefollowingcharacteristics:(1)smallerrorsoccurmorefrequentlythanlargeones(2)positiveandnegativeerrorsareequallylikelytooccur(3)verylargeerrorsseldomoccur.

在实践中发觉，这些误差，即使称为随机，具备以下特点：小误差发生频率比大

（2）正面和负面误差发生可能性相同

（3）非常大误差极少发生。Thesecharacteristicsaretypicaloferrorswhicharenormallydistributedanditisassumedthatwecanusethemathematicaltheorybasedonthenormaldistributiontodealwiththeerrorsmetwithinsurveying.正态分布是这些误差经典特点是，我们能够用基于正态分布数学理论来处理这些测量中误差。Understandingtheerrorsthatlimittheaccuracyofthemeasurementtechniquesisbutonesteptoensuringspecificationsareachieved,aswillbeseenwhenthemethodsofsurveyaredescribed:

了解限定测量方法精度误差仅仅是确保满足测量规范一步，按照以下测量方法进行：(a)Thesurveyareaisalwaystotallycoveredwiththesimplestpossibleframeworkofhighqualitymeasurements.Iftherestofthesurveyworkiscarriedoutwithinthiscontrolthepossibledamagingaccumulationoferrorscanbecontained.Thisisoftentermed'workingfromthewholetothepart',测区总是由高精度测量框架所覆盖。假如剩下测量工作在这个控制网内进行话，累积误差就能够得到有效地控制。这通常被称为“从整体到部分工作，(b)Observingproceduresaredesignedsothat(i)mostmistakesthatoccurarediscoveredimmediatelyand(ii)possiblesourcesofsystematicerrorseliminated.

（b）观察程序设计，（ⅰ）大多数误差及时被发觉，（ii）系统误差得到有效地控制。(c)Additional,orredundant,observationsaretakensothatalldatacanbecheckedforthemistakes,systematicerrorsandrandomerrorsthatdooccur.Forexample,thethreeanglesofatrianglewouldbeobservedalthoughonlytwoarerequiredtodefinetheshape.Thethirdanglecouldbededucedbut,whenmeasured,actsasacheck.

（c）多出观察是用来检测粗差、系统误差、偶然误差。比如，一个三角形观察中，只要观察两个角就能决定其形状。但第三角度观察是用来检核。(d)Manyquantitiesareobservedseveraltimes.Theserepeatedmeasurementsandtheobservationofredundantdataservebothaschecksandtoimproveontheprecisionofthefinalresults.

（d）许多数据需要数次观察。重复观察是用来检核并提升最终精度。CheckingthesurveyEvenwithallthecheckingproceduresthesurveyoremploys,errorscanstilloccurinthefinishedplanandforthisreasonfinalindependentchecksarerequired.Forsimpleworkthiswouldinvolveinspectingthefinalplaninthefieldandcomparingsomemeasurementsscaledofftheplanwiththeirequivalentsontheground.即使测量员按照检核步骤进行检核，不过误差依然能够出现在最终平面图中所以最终还需要进行独立检核。对于这项简单测量工作，需要到野外进行最终平面图纸检核和图纸距离放到实地进行比对。AngleandDirectionMeasurement角度和方向测量Horizontalandverticalanglesarefundamentalmeasurementsinsurveying.Itisnecessarytobefamiliarwiththemeaningsofcertainbasictermsbeforedescribingangleanddirectionmeasurement.Thetermsdiscussedherehavereferencetotheactualfigureoftheearth.水平角和竖直角是测量基本测量工作,在描述角度和方向测量之前，有必要熟悉几个基本术语含义,这里讨论这些术语与地球真实形状关于.BasicTerms基本术语Averticallineatanypointontheearth’ssurfaceisthelinethatfollowsthedirectionofgravityatthatpoint.Itisthedirectionthatastringwillassumeifaweightisattachedatthatpointandthestringissuspendedfreelyatthepoint.Atagivenpointthereisonlyoneverticalline.Ahorizontallineatapointisanylinethatisperpendiculartotheverticallineatthepoint.Atanypointthereareanunlimitednumberofhorizontallines.Ahorizontalplaneatapointistheplanethatisperpendiculartotheverticallineatthepoint.Thereisonlyonehorizontalplanethroughagivenpoint.Averticalplaneatapointisanyplanethatcontainstheverticallineatthepoint.Thereareanunlimitednumberofverticalplanesatagivenpoint.地球表面任一点垂线是指这点上沿着重力方向线,假如在这点上用线悬挂一个重物，当线自由静止时，这条线所展现方向即重力方向。在给定一个点上只有一条垂线。一点上水平线是垂直于过该点垂线直线。过任一点水平线有没有数条。过一点水平面是垂直于过该点垂线平面,过给定一个点只有一个水平面.过一点竖直面是包含过该点垂线任一平面过给定一点有没有数个竖直面.HorizontalAngleandVerticalAngle水平角和竖直角Ahorizontalangleistheangleformedinahorizontalplanebytwointersectingverticalplanes,orahorizontalanglebetweentwolinesistheanglebetweentheprojectionsofthelinesontoahorizontalplane.Forexample,observationstodifferentelevationpointsBandCfromAwillgivethehorizontalangle∠bacwhichistheanglebetweentheprojectionsoftwolines(ABandAC)ontothehorizontalplane.Itfollowsthat,althoughthepointsobservedareatdifferentelevations,itisalwaysthehorizontalangleandnotthespaceanglethatismeasured.Thehorizontalangleisusedprimarilytoobtainrelativedirectiontoasurveycontrolpoint,ortopographicdetailpoints,orpointstobesetout.Averticalangleisananglemeasuredinaverticalplanewhichisreferencedtoahorizontallinebyplus(up)orminus(down)angles,ortoaverticallinefromthezenithdirection.Plusandminusverticalanglesaresometimesreferredtoaselevationordepressionanglesrespectively.Averticalanglethusliesbetween0°and±90°.Zenithisthetermdescribingpointsonacelestialspherethatisasphereofinfinitelylargeradiuswithitscenteratthecenteroftheearth.Thezenithisananglemeasuredinaverticalplanedownwardfromanupwarddirectedverticallinethroughtheinstrument.Itisthusbetween0°and180°.水平角是指在一个水平面内由两相交竖直面形成角，或者说，两条线之间水平角是这两条线在水平面上投影线夹角.比如，在A点观察不一样高度B和C点，其水平角∠bac是由AB和AC两条线在水平面上投影组成.由此得出结论结论，即使被观察点在不一样高度上，测出总是水平角而不是空间角。水平角主要用来由联测控制点取得相对方向，或者地形测量碎部点、或者放样点,竖直角是在一个竖直面内参考于水平线正（仰）角或负（俯）角，或者相对于一个天顶方向垂线角.正负竖直角有时分别被称为仰角或俯角.Obviouslythezenithangleisequalto90°minustheverticalangles.Verticalanglesorzenithsareusedinthecorrectionofslopedistancetothehorizontalorinheightdetermined.Forthemostpart,theinstrumentusedinthemeasurementofanglesiscalledatransitortheodolite,althoughanglescanbemeasuredwithclinometers,sextants(hydrographicsurveys),orcompasses.Thetheodolitecontainsahorizontalandverticalcirclesofeitherglassorsilver.Thehorizontalandverticalcirclesoftheodolitecanbelinkedtocircularprotractorsgraduatedfrom0°to360°inaclockwisemannersetinhorizontalandverticalplane.Thehorizontalcircleisusedwhenmeasuringorlayingoffhorizontalanglesandtheverticalcircleisusedtomeasureorlayoffverticalanglesorzenithangles.Usuallytheunitsofangularmeasurementemployedinpracticearedegrees,minutes,andseconds,thesexagesimalsystem.竖直角位于0～90度之间.天顶方向是一个术语，用来描述在天球上点，天球是一个半径无限大球，其中心在地球中心。天顶距是一个在竖直面内从一个过仪器被定向为向上竖直方向线向下测量角。它范围是从0到180度。显然，天顶距等于90度减去竖直角.竖直角或天顶距用于斜距化平距改过或者高程测量.在极大程度上，用来测角工具被称为经纬仪，即使角度能够用倾斜仪、六分仪、或罗盘仪来测，经纬仪有一个玻璃或镀银水平度盘和竖直度盘.经纬仪水平度盘和竖直度盘与顺时针刻了0到360度刻划圆分度器相连。测或拨水平角时用水平度盘，测或拨竖直角或天顶距时用竖直度盘，通常角度测量法使用单位是六十进制度、分、秒。AngleMeasurement角度测量Ahorizontalangleinsurveyinghasadirectionorsense;thatis,itismeasuredordesignedtotherightortotheleft,oritisconsideredclockwiseorcounterclockwise.Intheabovefigure,theangleatAfromBtoCisclockwiseandtheanglefromCtoBiscounterclockwise.Withthetheodolitesetup,centered,andleveledoveratstationA,thenasimplehorizontalanglemeasurementbetweensurveyingpointB,AandCwouldbetakenasfollows:在测水平角有方向，就是说它是向左测还是向右测，或者是说，顺时针测还是逆时针测.如上图所表示，在A点由B到C就是顺时针角，而从C到B就是逆时针角，经纬仪在A点安置、对中、整平后，在B、A和C测量点间简单水平角测量能够按以下步骤进行：=1\*GB2⑴Commencingon,say,“faceleft”,thetargetsetatsurveypointBiscarefullybisectedandthereadingonhorizontalscaleis25°.=2\*GB2⑵TheupperplateclampisreleasedandtelescopeisturnedclockwisetosurveypointC.Thereadingonhorizontalcircleis75°=3\*GB2⑶Thehorizontalangleisthenthedifferenceofthetwodirections,i.e.(75°-25°)=50°=1\*GB2⑴说示意，“盘左”，将B点目标仔细分中，水平度盘读数为25度=2\*GB2⑵水平度盘制动螺旋松开，顺时针转动望远镜至C点，水平度盘读数75度=3\*GB2⑶水平角就是两个方向值差值，即，(75°-25°)=50°=4\*GB2⑷ChangefaceandobservepointCon“faceright”,andnotethereading=255°=5\*GB2⑸ReleaseupperplateandswingcounterclockwisetopointBandnotethereading=205°=6\*GB2⑹Thereadingorthedirectionmustbesubtractedinthesameorderas255°-205°=50°=7\*GB2⑺Themeanoftwovalueswouldbeacceptediftheyareinacceptableagreement.=4\*GB2⑷换度盘方向至盘右并照准C点，记下读数为255度=5\*GB2⑸松开水平度盘，逆时针旋转至B点并记下读数为205度=6\*GB2⑹读数或者说是方向值按一样法则相减，255°-205°=50°=7\*GB2⑺假如两个减出来值一致性是可接收，取两个值平均值。Modernelectronicdigitaltheodolitescontaincircularencodersthatsensetherotationsofthespindlesandthetelescope,converttheserotationsintohorizontalandvertical(orzenith)angleselectronically,anddisplaythevalueoftheanglesonliquidcrystaldisplays(LCDs)orlight-emittingdiodedisplays(LEDs).Thesereadoutscanberecordedinaconventionalfieldbookorcanbestoredinadatacollectorforfutureprintoutorcomputation.Theinstrumentcontainsapendulumcompensatororsomeotherprovisionforindexingtheverticalcirclereadingstoanabsoluteverticaldirection.Thecirclecanbesettozeroreadingsbyasimplepressofabuttonorinitializedtoanyvalueontheinstrument.Azimuthisthehorizontalanglemeasuredinaclockwisedirectionfromtheplaneofthemeridian,whichisalineonthemeansurfaceoftheearthjoiningthenorthandsouthpoles.Azimuthrangesinmagnitudefrom0°to360°,valuesinexcessof360°,whicharesometimesencounteredincomputations,aresimplyreducedby360°beforefinallisting.Bearingisthetraditionalwayofstatingtheorientationoftheline.Itisactuallytheanglemeasuredfromthenorthorsouth.Thebearing,whichcanbemeasuredclockwiseorcounterclockwisefromthenorthorsouthendofthemeridian,isalwaysaccompaniedbylettersthatlocatethequadrantinwhichthelinefalls.Forexample,bearingN32Windicatesalinetrending32°westofthenorth.Itisequaltoanazimuthof328°.BearingS12Windicatesalinetrending12°westofthesouth.Itisequaltoanazimuthof192°.Itisimportanttostatethatthebearingandazimutharerespecttotruenorth.当代电子数字经纬仪包含编码度盘，能够感知轴和望远镜旋转，并使之电子地转换为水平角度和竖直角度，并在液晶显示器或发光二极管显示器上显示出来，这些显示能够被一个传统野外电子手簿或数据搜集器统计，方便日后打印或计算。这种仪器具备一个悬挂赔偿器或其它装置，使竖盘指标读数指向一个绝对竖直方向，这个度盘能够经过简单按一个键就将其置零，或初始化成任一值。方位角是从子午面起算按顺时针旋转角，子午线是在地球平均表面连接北极与南极线。方位角取值范围从0度到360度，超出360值――有时会在计算时碰到，只需减去360度即可。方向角是一个传统描述直线方向方法。实际上，它是从南或北方向开始量测角，方向角能够从子午线，北端或南端以顺时针或逆时针量测，总是伴以字母，用来标明直线所落在象限。方向角N32W代表一条直线从北方向转向西方向32度，它等于方位角328度，方向角S12W代表一条直线从南方向转向西方向12度，它等于方位角192度。需要重点说明是，方向角和方位角所用是真北方向。Unit5Traversing（导线测量）Thepurposeofthesurveyingistolocatethepositionsofpointsonornearthesurfaceoftheearth.（测量目标是确定地表或靠近地表点点位。）Todeterminehorizontalpositionsofarbitrarypointsontheearth’ssurfaceandelevationofpointsaboveorbelowareferencesurfaceareknownasacontrolsurvey.（确定地表任一【arbitrary任意】点平面位置和确定点高于或低于一个参考面高程工作被称为控制测量）Thepositionsandelevationsofthepointsmakeupacontrolnetwork.（这些点平面位置和高程组成了一个控制网）Therearedifferenttypesofcontrolnetworksdependingonwhereandwhytheyareestablished.（依照它们建立地点和目标不一样，有不一样控制网类型）Acontrolnetworkmayhaveveryaccuratepositionsbutnoelevations(calledaHorizontalControlNetwork)orveryaccurateelevationsbutnopositions(calledaVerticalControlNetwork).（一个控制网可能有精准平面位置而没有高程（称为平面控制网），或者有精准高程而没有平面位置（称为高程控制网））Somepointsinacontrolnetworkhavebothaccuratepositionsandelevations.（有些控制网点现有精准平面位置也有精准高程）Controlnetworksrangefromsmall,simpleandinexpensivetolargeandcomplexandveryexpensivetoestablish.（控制网范围从小、简单、廉价网到大、复杂、昂贵网）Acontrolnetworkmaycoverasmallareabyusinga“local”coordinatesystemthatallowsyoutopositionthefeaturesinrelationtothecontrolnetworkbutdoesn’ttellyouwherethefeaturesareonthesurfaceoftheearth,orcoveralargeareabyconsistingofafewwell-placedandprecise-establishedcontrolpoints,whichissometimescalledtheprimarycontrol.（一个控制网能够是覆盖小范围，使用区域坐标系统，允许你相对于控制网确定地貌特征【feature】，但却不告诉你它们在地表什么地方；或者覆盖一个广大区域，由少数被适当安置并精准测设控制点组成，有时被称为基础控制）Thehorizontalpositionsofpointsinanetworkcanbeobtainedinanumberofdifferentways.（控制网点平面位置能够由许多不一样方法来取得）Thegenerallyusedmethodsaretriangulation,trilateration,traversing,intersection,resectionandGPS.（通常使用方法有，三角测量、三边测量、导线测量、交会测量、后方交会测量、和GPS测量）Themaintopicofthistextreferstothetraversing.（这篇课文主要讲是导线测量）Triangulation（三角测量）Themethodofsurveyingcalledtriangulationisbasedonthetrigonometricpropositionthatifonesideandthreeanglesofatriangleareknown,theremainingsidescanbecomputedbythelawofsines.（这种测量方法称为三角测量，基于三角法则，假如三角形一条边和三个角已知，剩下边能够用正弦定理计算出）Furthermore,ifthedirectionofonesideisknown,thedirectionoftheremainingsidescanbedetermined.（而且，假如一条边方向已知，余下边方向也能够确定）Andthencoordinatesofunknownpointscanbecomputedbyapplicationoftrigonometry.（那么未知点坐标就能够使用三角法计算出来）Trilateration（三边测量）Sincetheadventoflong-rangeEDMinstrument,amethodofsurveyingcalledtrilaterationwasadoptedtocombinewithtriangulation.（自从远距EDM出现以来，一个叫做三边测量方法用来和三角测量联合使用。）Thetrilaterationisbasedonthetrigonometricpropositionthatifthethreesidesofatriangleareknown,thethreeanglescanbecomputedbythelawofcosines.（三边测量基于三角法则——假如三角形三条边已知，那么三个角能够由余弦定理计算出）TrilaterationpossessessomeadvantagesovertriangulationbecausethemeasurementofthedistanceswithEDMinstrumentissoquick,preciseandeconomicalwhilethemeasurementoftheanglesneededfortriangulationmaybemoredifficultandexpensive.（三边测量具备一些相对于三角测量优势，EDM测距快速、准确、经济，而三角测量所需角度测量则相对困难和昂贵）Forsomepreciseprojects,thecombinationoftriangulationandtrilaterationwhichiscalledtriangulaterationisapplied.（在一些精密工程当中，三角测量和三边测量联合使用，被称为边角测量）Traversing（导线测量）Asurveytraverseisasequenceoflengthsanddirectionsoflinesbetweenpointsontheearth,obtainedbyorfromfieldangleanddistancemeasurementsandusedindeterminingpositionsofthepoint.（导线是一系列地球上点之间有长度和方向直线，由野外角度和距离测量取得，用来确定点位）Theanglesaremeasuredusingtransits,theodolites,ortotalstations,whereasthedistancescanbemeasuredusingsteeltapesorEDMinstruments.（角度能够使用经纬仪或全站仪来测，而距离能够使用卷尺或EDM来测）Asurveytraversemaydeterminetherelativepositionsofthepointsthatifconnectsinseries,andiftiedtocontrolstationsbasedonsomecoordinatesystem,thepositionsmaybereferredtothatsystem.（导线能够用来确定相互连接点相对位置，假如想控制一些坐标系中站点，其位置应参考该坐标系）Fromthesecomputedrelativepositions,additionaldatacanbemeasuredforlayoutofnewfeatures,suchasbuildingsandroads.（从这些计算出相对位置，另外数据能够量出来，用以放样新地物，如：建筑物和道路。）SincetheadventofEDMequipment,traversinghasemergedasthemostpopularmethodtoestablishcontrolnetworkssuchasbasicareacontrol,mapping,controlofhydrographicsurveysandconstructionprojects.（自从EDM出现，导线测量作为最惯用建立控制网方法显现出来，比如基础区域控制、图根控制、水道测量控制和建筑工程控制）Inengineeringsurveying,itisidealwaytosurveysanddimensionalcontrolofroute-typeprojectssuchashighway,railroad,andpipelineconstruction.（在工程测量当中，导线测量是线型工程测量和立体控制理想方法，线型工程比如公路、铁路、和管线建筑）Ingeneral,atraverseisalwaysclassifiedaseitheranopentraverseoraclosedtraverse.（总体上，导线总是分为支导线和闭路导线【按说opentraverse是支导线，closedtraverse是闭合导线，而connectingtraverse是附合导线】）Anopentraverseoriginateseitheratapointofknownhorizontalpositionwithrespecttoahorizontaldatumoratanassumedhorizontalposition,andterminatesatastationwhoserelativepositionisnotpreviouslyknown.（支导线起始于一个水平位置已知（相对于一个水平基准）或水平位置假定点，终止于相对位置事先未知站点。）Theopentraverseprovidesnocheckagainstmistakesandlargeerrorsforitsterminationatanunknownhorizontalpositionandlackofgeometricclosure.（因为其终点位置未知而且缺乏图形闭合，支导线不能提供对错误和较大误差检核）Thislackofgeometricclosuremeansthatthereisnogeometricverificationpossiblewithrespecttotheactualpositioningofthetraversestations.（这种图形闭合缺乏意味着没有几何上检核可能性，对于实际导线点确实定。）Thus,themeasuringtechniquemustberefinedtoprovideforfieldverification.（因而，这种测量技术应该提供野外检核使之精准。）【字面意思是该技术应该被精准化提供给野外确认】Ataminimum,distancesaremeasuredtwiceandanglesaredoubled.（最少，距离测两遍，角度测两个测回。）Opentraversesareoftenusedforpreliminarysurveyforaroadorrailroad.（支导线经惯用于道路或铁路初测）Aclosedtraversecanbedescribedinanyoneofthefollowingtwoways:（闭路导线能够由下面两种方式任一个描述：）=1\*GB2⑴Aclosedlooptraverse,asthenameimplies,formsacontinuousloop,enclosinganarea.（闭合环路导线，正如名字所表示，呈一个连续环，围绕一个区域）Thistypeofclosedtraversestartsatassumedhorizontalpositionorataknownhorizontalpositionwithrespecttoahorizontaldatumandendsatthesamepoint.（这种闭路导线起始于一个平面位置假设或相对于一个水平基准已知点，并终止于该点）=2\*GB2⑵Aconnectingtraversestartsandendsatseparatepoints,whoserelativepositionshavebeendeterminedbyasurveyofequalorhigherorderaccuracy.（附合导线起始和终止于不一样点，它们由等于或高于要求精度测量测设）Aknownhorizontalpositionisdefinedbyitsgeographiclatitudeandlongitude,orbyitsXandYcoordinatesonagridsystem.（一个已知水平位置是由它大地经纬度或格网系XY坐标表示）Closedtraverses,whethertheyreturntothestartingpointornot,providechecksonthemeasuredanglesanddistances.（闭合导线，不论它们是否回到起始点，都能提供角度和距离检核。）Inbothcases,theanglescanbeclosedgeometrically,andthepositionclosurecanbedeterminedmathematically.（在两种情况中，角度能够在几何上闭合，位置闭合能够数学确实定【计算出来】）Thereforetheyaremoredesirableandusedextensivelyincontrol,construction,property,andtopographicsurveys.（所以它们更理想【desirable理想】，在控制测量、建筑测量、房地产测量和地形测量使用更广泛）Aswementionedabove,aclosedtraverseprovideschecksonthemeasuredanglesanddistances.（正如我们上面所提到，闭合导线能够提供角度和距离检核）Forexample,thegeometricsumoftheinterioranglesinann-sideclosedfigureshouldbe(n-2)×180°,butduetosystematicandrandomerrorsofthemeasurements,whenalltheinterioranglesofaclosedtraversearesummed,theymayormaynottotalthenumberofdegreesrequiredforgeometricclosure.（比如，在一个n边闭合图形当中，内角和应该是：(n-2)×180°，不过因为【dueto】测量中系统误差和偶然误差存在，当闭合导线全部内角加起来后，其角度和【total】可能等于或不等于其几何理论闭合差值）Thedifferencebetweenthegeometricsumandactualfieldsumoftheinterioranglesiscalledangularclosure.（内角和理论值和实际值差值被称为角度闭合差）Thetotalerrorofangularclosureshouldbedistributedevenlytoeachangle(ifallanglesweremeasuredwiththesameprecision)beforemathematicalanalysisofthetraverse.（在导线进行数学分析之前，角度闭合差应该平均分配到每个角上（假如全部角都是相同观察精度））Theimportantpointbeforedoingthisisthattheoverallangularclosurecan’tbebeyondthesurveyspecifications.（主要一点是，在这么做之前，全部闭合差都不得超出测量规范）Closedtraversesprovidealsochecksonthemeasureddistances,andthepositionclosurecanbedeterminedmathematically,whichmeansthatanindicationoftheconsistencyofmeasuringdistancesaswellasanglesshouldbegiventoatraversethatclosesonitself.（闭合导线同时提供测量过距离检核，位置闭合差能够计算得到，这就意味着测量距离同测角一样，应该给予闭合Theoreticallythispositionclosurefromtheoriginbacktoitselfshouldbezero.（理论上，从起点闭合到它自己，位置闭合差应该是0）ButtheErrorsinthemeasureddistancesandanglesofthetraverses,however,willtendtoaltertheshapeofthetraverse,thereforeweshouldcomputethealgebraicsumofthelatitudesandalgebraicsumofthedepartures,andcomparethemwiththefixedlatitudeanddepartureofastraightlinefromtheorigintotheclosingpoint.（不过距离和角度测量误差，会改变【alter】导线形状，所以我们应该分别计算纵距与横距代数和，然后与从起点到终点连线确实定纵距与横距相比较）Bydefinition,latitudehereisthenorth/southrectangularcomponentofalineanddepartureistheeast/westrectangularcomponentofaline.（精准说，这里纵距就是指一条直线直角坐标南北分量，横距就是指一条直线直角坐标东西分量）Todifferentiatedirection,northisconsideredplus,whereassouthisconsideredminus.（对于不一样方向来说，北方向为正，南方向为负）Similarly,eastisconsideredplus,whereaswestisconsideredminus.（一样，东为正，西为负）Thenthediscrepancyshouldbeadjustedbyapportioningtheclosurebothinlatitudesandindeparturesonareasonablebasis.（然后差值应以合理标准进行调整分配闭合差到纵距和横距上去）Theadjustedpositionofeachtraversepointisdeterminedwithrespecttosomeorigin.（ThispositionisdefinedbyitsYcoordinatesanditsXcoordinateswithrespecttoaplanerectangularcoordinatesysteminwhichtheYaxisisassumednorth-southwhereastheXaxiseast-west.（其位置由平面直角坐标系Y坐标和X坐标来定义，Y轴代表南北方向，而【whereas反之】X轴代表东西方向）Unit6MethodsofElevationDetermination（高程测量方法）Anelevationisaverticaldistanceaboveorbelowareferencedatum.（高程是高于或低于一个参考基准一个垂直距离。）Althoughverticaldistancecanbereferencedtoanydatum,insurveying,thereferencedatumthatisuniversallyemployedisthatofmeansealevel(MSL).（即使垂直距离能够参考任何一个基准，不过在测量上，这个参考基准通常使用是平均海平面（MSL））MSLisassignedaverticalvalue(elevation)of0.000ftor0.000m.（MSL被赋予一个0.000英尺或0.000米高程）Allotherpointsontheearthcanbedescribedbytheelevationsaboveorbelowzero.（地球上全部其它点能够用高于或低于0高程来描述）Permanentpointswhoseelevationshavebeenpreciselydetermined(benchmarks)areavailableinmostareasforsurveyuse.（高程精准测出永久点（水准点）被用于大多数区域测量工作）InChina,7yearsofobservationsattidalstationsinQingdaofrom1950to1956werereducedandadjustedtoprovidetheHuanghaiverticaldatumof1956.（在中国，利用青岛验潮站从1950年到1956年7年观察数据处理和平差，建立了56黄海高程系统）Inthe1987,thisdatumwasfurtherrefinedtoreflectlongperiodicaloceantidechangetoprovideanewnationalverticaldatumof1985,accordingtotheobservationsattidalstationsfrom1952to1979.（1987年，在依照了验潮站1952到1979年观察资料后，这个基准被深入精准——反应长时期海潮改变85国家高程基准建立起来。）Although,strictlyspeaking,thenationalverticaldatummaynotpreciselyagreewiththeMSLatspecificpointsontheearth’ssurface,thetermMSLisgenerallyusedtodescribethedatum.（即使，严格说来，国家高程基准在特殊点上与MSL并不恰好吻合，术语MSL通常还是用来描述它）MSLisassignedaverticalvalue(elevation)of0.000ftor0.000m.（MSL高程赋值为0.000英尺或米）Differenceinelevationmaybemeasuredbythefollowingmethods:(JamesM.AndersonandEdwar