《数字测图》课件-3.4.2三维激光扫描仪进行野外数据采集基本知识认识

数字测图DigitalMapping3DLaserScannerforFieldDataCollectionBasicKnowledgeUnderstanding三维激光扫描仪进行野外数据采集基本知识认识三维激光扫描数据采集是一种集成了多种高新技术的新型测绘手段，采用非接触式高速激光测量方式，以点云的形式获取地形及复杂物体三维表面的阵列式几何图形数据。Three-dimensionallaserscanningdatacollectionisanewsurveyingmethodthatintegratesvarioushigh-techtechnologies.Itusesanon-contact,high-speedlasermeasurementmethodtoobtainpointclouddataintheformofaseriesofgeometricgraphicsforthethree-dimensionalsurfaceofterrainandcomplexobjects.三维激光扫描仪进行野外数据采集基本知识认识3DLaserScannerforFieldDataCollectionBasicKnowledgeUnderstanding三维激光扫描系统(3DLSS)，也被称为三维激光成图系统，它主要是由三维激光扫描仪和系统软件组成。方便、快速、准确地获取近距离静态物体的空间三维模型就是它的工作目标，这样可以方便对模型进行进一步的分析和数据处理。Thethree-dimensionallaserscanningsystem(3DLSS),alsoknownasthethree-dimensionallasermappingsystem,mainlyconsistsofathree-dimensionallaserscannerandsystemsoftware.Itsworkgoalistoobtainathree-dimensionalspatialmodelofstaticobjectsatashortdistanceinaconvenient,fast,andaccuratemanner,sothatthemodelcanbefurtheranalyzedandprocessed.三维激光扫描仪进行野外数据采集基本知识认识3DLaserScannerforFieldDataCollectionBasicKnowledgeUnderstanding

三维激光扫描技术是一种全自动先进的高精度立体扫描技术，能够完整并高精度的重建扫描实物和快速获得原始测量数据。它是继GNSS技术以来测绘领域的又一次技术革命，将使测绘服务能力与水平数据的获取方法、数据处理方法等进入更全面、更新的发展阶段。Three-dimensionallaserscanningtechnologyisanadvanced,automatic,andhigh-precisionthree-dimensionalscanningtechnologythatcancompletelyandaccuratelyreconstructscannedobjectsandquicklyobtainoriginalmeasurementdata.ItisanothertechnologicalrevolutioninthesurveyingandmappingfieldafterGNSStechnology,whichwillmakethesurveyingandmappingservicecapabilitiesandtheacquisitionandprocessingmethodsofdataenteramorecomprehensiveandnewerdevelopmentstage.三维激光扫描仪进行野外数据采集基本知识认识3DLaserScannerforFieldDataCollectionBasicKnowledgeUnderstanding

传统的大地测量方法，如三角测量方法，CPS测量都是基于点的测量，而三维激光扫描是基于面的数据采集方式。三维激光扫描获得的原始数据为点云数据。Traditionallandsurveymethods,suchastriangulationmethodandCPSmeasurement,arebasedonpointmeasurement,whilethree-dimensionallaserscanningisbasedondataacquisitionofsurfaces.Theoriginaldataobtainedbythree-dimensionallaserscanningispointcloud.三维激光扫描仪进行野外数据采集基本知识认识3DLaserScannerforFieldDataCollectionBasicKnowledgeUnderstanding

三维激光扫描技术，具有高精度、速度快、分辨率高非接触式兼容性好等优势。比起传统的测量技术，如全站仪技术、航空摄影测近景量摄影测量等。Thethree-dimensionallaserscanningtechnologyhastheadvantagesofhighprecision,highspeed,highresolution,non-contact,andgoodcompatibility.Comparedwithtraditionalmeasurementtechnologiessuchastotalstationtechnology,aerialphotogrammetry,andclose-rangephotogrammetry.三维激光扫描技术特点CharacteristicsofThree-dimensionalLaserScanningTechnology01非接触式Non-contact三维激光扫描技术采用的测量方式为非接触式高速激光测量方式，它不需要反射棱镜，直接对目标体进行扫描，采集的是目标体表面云点的三维坐标信息。Themeasurementmethodofthree-dimensionallaserscanningtechnologyisanon-contacthigh-speedlasermeasurementmethod.Itdoesnotneedreflectionprismsanddirectlyscansthetargetbodytocollectthethree-dimensionalcoordinateinformationofthesurfacecloudpointsofthetargetbody.三维激光扫描技术特点CharacteristicsofThree-dimensionalLaserScanningTechnology02扩展性强、数字化程度高StrongExpandabilityandHighDegreeofDigitalization扩展性强、数字化程度高。三维激光扫描系统是把采集的数字信号作为数据，数据具有全数字的特征，易于分析、处理、输出和显示。Strongexpandabilityandhighdegreeofdigitalization.Thethree-dimensionallaserscanningsystemtreatsthecollecteddigitalsignalasdata,andthedatahasthecharacteristicsoffulldigital,whichiseasytoanalyze,process,outputanddisplay.三维激光扫描技术特点CharacteristicsofThree-dimensionalLaserScanningTechnology03数据采样率高HighDataSamplingRate目前，采用脉冲激光或时间激光的三维激光扫描仪采样点速率可达到数千点/s，而采用相位激光方法测量的三维激光扫描仪甚至可以达到数十万点/s。Highdatasamplingrate:Currently,thesamplingrateofthree-dimensionallaserscanningsystemswithpulselasersortimelaserscanreachthousandsofpoints/s,andthree-dimensionallaserscanningsystemswithphaselaserscanevenreachtensofthousandsofpoints/s.三维激光扫描技术特点CharacteristicsofThree-dimensionalLaserScanningTechnology04高分辨率HighDataSamplingRate三维激光扫描技术可以进行快捷、高质量高密度的三维数据采集，从而达到高分辨率的目的。Three-dimensionallaserscanningtechnologycanquicklyandefficientlycollectthree-dimensionaldatawithhighqualityanddensity,therebyachievinghighresolution.三维激光扫描技术特点CharacteristicsofThree-dimensionalLaserScanningTechnology一台高速精确的激光测距仪，配上一组可以引导激光并以均匀角速度扫描的反射棱镜就是三维激光扫描仪的主要构造。Ahigh-speedandpreciselaserdistancemeasuringinstrument,combinedwithasetofreflectionprismsthatcanguidethelaserandscanatauniformangularspeed,constitutesthemainstructureofathree-dimensionallaserscanner.三维激光扫描仪工作原理WorkingPrincipleofThree-dimensionalLaserScanner发射激光的是激光测距仪，与此同时接收由自然物表面反射的信号从而可以进行测距，针对每一个扫描点可测得测站至扫描点的斜距，再配合扫描的水平和垂直方向角，可以得到每一扫描点与测站的空间相对坐标。如果测站的空间坐标是已知的，那么则可以求得每一个扫描点的三维坐标。Thelaserdistancemeasuringinstrumentemitsthelaser,andatthesametimereceivesthesignalreflectedbythenaturalobjectsurface,whichcanbeusedfordistancemeasurement.Foreachscannedpoint,thedistancefromthestationtothescannedpointcanbemeasured,andbycombiningthehorizontalandverticalangularscanningdirection,thespatialrelativecoordinateofeachscannedpointrelativetothestationcanbeobtained.Ifthespatialcoordinatesofthestationareknown,thenthethree-dimensionalcoordinatesofeachscannedpointcanbecalculated.三维激光扫描仪工作原理WorkingPrincipleofThree-dimensionalLaserScanner三维激光扫描仪的分类ClassificationofThree-dimensionalLaserScanners按照扫描平台Basedonthescanningplatform按照三维激光扫描仪的有效扫描距离Basedontheeffectivescanningdistanceofthethree-dimensionallaserscannerGround-basedLaserScanningSystems地面型激光扫描系统01Airborne(orSatellite-based)LaserScanningSystems机载（或星载）激光扫描系统02PortableLaserScanningSystems便携式激光扫描系统03Basedonthescanningplatform按照扫描平台Ground-basedLaserScanningSystems地面型激光扫描系统01固定式的激光扫描系统Fixed-typelaserscanningsystems移动式激光扫描系统Mobile-typelaserscanningsystems机载（或星载）类型激光扫描系统是由飞行惯导系统（INS），激光扫描仪（LS），成像装置（UI），DGPS定位系统，计算机和数据采集器、记录器、处理软件及电源构成。Aircraft-based(orsatellite-based)typelaserscanningsystemsconsistofinertialnavigationsystems(INS),laserscanners(LS),imagingdevices(UI),DGPSpositioningsystems,computers,dataacquisitiondevices,recorders,processingsoftware,andpowersupplies.Airborne(orSatellite-based)LaserScanningSystems机载（或星载）激光扫描系统02手持型激光扫描仪是移动式激光扫描系统，是集成了激光扫描仪，CCD相机以及彩色数码相机，数据采集和记录装置。由激光扫描仪和CDC相机获取原始数据，作为三维建模的数据源。Handheldlaserscannersaremobilelaserscanningsystemsthatintegratelaserscanners,CCDcameras,andcolordigitalcameras,dataacquisitionandrecordingdevices.TheoriginaldataisobtainedbythelaserscannerandCCDcamera,whichservesasthedatasourceforthree-dimensionalmodeling.Handheldlaserscanner手持型激光扫描仪03短距离三维激光扫描仪Short-rangethree-dimensionallaserscanners中距离三维激光扫描仪Medium-rangethree-dimensionallaserscanners长距离三维激光扫描仪Long-rangethree-dimensionallaserscanners航空三维激光扫描仪Aerialthree-dimensionallaserscanners.Basedontheeffectivescanningdistanceofthethree-dimensionallaserscanner按照三维激光扫描仪的有效扫描距离数据采集可以分为几个步骤：踏勘场地与布设控制网、控制测量、靶标布设、靶标测量与提取、扫描作业、纹理采集。Dataacquisitioncanbedividedintoseveralsteps:sitesurveyandlayoutofcontrolnetwork,controlmeasurement,targetsetting,targetmeasurementandextraction,scanningoperation,andtextureacquisition.三维激光扫描仪外业操作流程FieldOperationProcessofThree-dimensionalLaserScanning一踏勘场地SiteSurvey根据现场情况估计扫描测站应设的站数和位置，尽量保证扫描区域有公共部分，减少其他物体的遮挡，且也应保证扫描距离在扫描仪的有效测程内。Estimatethenumberandlocationofscanstationsbasedonthesiteconditions,toensurethatthescanningareahasapublicarea,reducetheobstructionofotherobjects,andalsoensurethatthescanningdistanceiswithintheeffectiverangeofthescanner.三维激光扫描仪外业操作流程FieldOperationProcessofThree-dimensionalLaserScanning一踏勘场地SiteSurvey控制点的布设在扫描测站开始前，按照扫描测站情况来进行要保证每一控制点和至少2个其他控制点通视，且控制点通视区域应尽量包含待扫描区域。Thelayoutofcontrolpointsshouldbecarriedoutbeforethestartofthescanstations,accordingtothesituationofthescanstations.Itisrequiredtoensurethateachcontrolpointisvisiblefromatleasttwoothercontrolpoints,andthevisibilityareaofthecontrolpointsshouldtocontainthescanningarea.三维激光扫描仪外业操作流程FieldOperationProcessofThree-dimensionalLaserScanning二获得高精度的靶标点位ObtainHigh-precisionTargetPointPositions为了布设高精度的控制网，获取高精度的控制点坐标，将控制测量分为高程控制测量及平面控制测量，分别进行测量与平差计算，这样获得高精度的靶标点位，并为后续的配准提供精确的转换坐标。Inordertolayoutahigh-precisioncontrolnetworkandobtainhigh-precisioncontrolpointcoordinates,elevationcontrolmeasurementsandplanecontrolmeasurementsarecarriedoutseparately,andmeasurementandadjustmentcalculationsarecarriedouttoobtainhigh-precisiontargetpointpositionsandprovidepreciseconversioncoordinatesforsubsequentregistration.三维激光扫描仪外业操作流程FieldOperationProcessofThree-dimensionalLaserScanning三准确地提取靶标中心点AccuratelyExtracttheTargetMarkerCenter靶标按作用可分为拼接标靶和控制标靶，拼接标靶用来进行两站的点云数据配准，控制标靶用来纠正点云数据到真实坐标。拼接标靶和控制标靶均需采取较高分辨率的进行扫描，以便能准确地提取靶标中心点。Targetmarkerscanbedividedintopatchmarkersandcontrolmarkers,patchmarkersareusedforregisteringpointclouddatabetweentwostations,andcontrolmarkersareusedtocorrectpointclouddatatorealcoordinates.Bothpatchmarkersandcontrolmarkersneedtobescannedwithhighresolutiontoaccuratelyextractthetargetmarkercenter.三维激光扫描仪外业操作流程FieldOperationProcessofThree-dimensionalLaserScanning四设置相应的扫描分辨率SettheAppropriateScanResolution扫描作业采用地面三维激光扫描仪，根据所需目标物的点云密集程度设置相应的扫描分辨率。Scanningisperformedusingaground-basedthree-dimensionallaserscanner,andthescanningresolutionissetaccordingtothepointclouddensityrequiredforthetargetobject.三维激光扫描仪外业操作流程FieldOperationProcessofThree-dimensionalLaserScanning点云数据预处理PointCloudDataPreprocessing（1）点云数据去噪PointCloudDataDenoising（2）点云数据压缩PointCloudDataCompression（3）点云数据封装PointCloudDataPackaging三维激光扫描仪外业操作流程FieldOperationProcessofThree-dimensionalLaserScanning原始点云数据在采集的过程中，受到采集设备本身以及环境因素的影响，其中包含了大量的无用数据，这些无用数据因为含有大量误差，因此也被称为噪声点。噪声数据的存在会降低三维坐标的计算精度，同时也会增加计算量。Therawpointclouddatacollectedduringtheacquisitionprocessisaffectedbythecollectionequipmentitselfandenvironmentalfactors,andcontainsalargeamountofuselessdata.Theseuselessdataareconsiderednoisepointsbecausetheycontainalargeamountoferrors.Theexistenceofnoisedatawillreducetheaccuracyofthree-dimensionalcoordinatesandalsoincreasethecomputingload.（1）点云数据去噪PointCloudDataDenoising三维激光扫描仪外业操作流程FieldOperationProcessofThree-dimensionalLaserScanning三维激光扫描技术与其他测绘技术相比，精度更高。而这一优点的实现主要依赖大量的点云数据。大量的点云数据虽然能够更为全面、准确的描绘目标物体。Comparedwithothersurveyingtechnologies,three-dimensionallaserscanningtechnologyhashigheraccuracy.Andthisadvantageismainlydependentonalargeamountofpointclouddata.Alargeamountofpointclouddatacanmorecomprehensivelyandaccuratelydescribethetargetobject.（2）点云数据压缩PointCloudDataCompression三维激光扫描仪外业操作流程FieldOperationProcessofThree-dimensionalLaserScanning但与此同时，大量的点云数据也增加了后续的处理时间，给系统带来了巨大压力，因此在不影响测绘的目的下，需要进行压缩处理。压缩处理方法主要包括统一采样法、曲率采样法等间距采样法、随机抽样法等几种。Butatthesametime,alargeamountofpointclouddataalsoincreasesthesubsequentprocessingtimeandputsgreatpressureonthesystem.Therefore,datacompressionisneededinordertonotaffectingthepurposeofsurveying.Thecompressionmethodsmainlyincludeuniformsamplingmethod,curvaturesamplingmethod,etc.spacingsamplingmethod,randomsamplingmethod,etc.（2）点云数据压缩PointCloudDataCompression三维激光扫描仪外业操作流程FieldOperationProcessofThree-dimensionalLaserScanning将处理好的点云数据进行网格化处理，即按就近原则连接相邻数据点，创建多边形几何模型。Theprocessedpointclouddataistreatedwithmeshprocessing,whichconnectsadjacentdatapointsbythenearestprincipleandcreatespolygonalgeometricmodels.（3）点云数据封装PointCloudDataPackaging三维激光扫描仪外业操作流程FieldOperationProcessofThree-dimensionalLaserScanningPointCloudDataRegistration点云数据配准点云数据一般来自不同的测站，每一测站负责一部分点云数据的获取，因此采集的点云数据并不是完整的，需要将每一测站的点云数据映射到统一坐标系统当中，构成一个大的目标区域的完成点云数据。以上过程就被称为点云数据的配准。目前点云数据配准方法主要有三种，即基于标靶的配准方法、基于特征点的配准方法和基于ICP算法拼接方法。Pointclouddataisusuallycollectedfromdifferentstations,whereeachstationisresponsibleforcollectingaportionofpointclouddata.Therefore,thecollectedpointclouddataisnotcompleteandneedstobemappedtoaunifiedcoordinatesystem,whichconstitutesacompletepointclouddataforalargetargetarea.Theaboveprocessiscalledpointclouddataregistration.Currently,therearethreemainmethodsforpointclouddataregistration,includingtarget-basedregistrationmethod,featurepoint-basedregistrationmethod,andICPalgorithm-basedstitchingmethod.Three-dimensionalModelConstruction三维模型构建三维模型构建是三维激光扫描技术的最后一个环节，即利用上述处理好的点云数据，进行三维模型构建。在这里需要借助一种强大的后处理软件进行建模，建模流程主要包括两项任务，即粗建模和纹理映射。前者过程是将处理的好的点云数据按照最近原理来构造的三角网格面，使得整个轮廓不但接近目标原型，然后再通过曲面拟合的方法，经过反复的修补、光滑，完成对三维模型的构建。Three-dimensionalmodelconstructionisthelaststepinthree-dimensionallaserscanningtechnology,whichinvolvesusingtheprocessedpointclouddatatoconstructthree-dimensionalmodels.Thisprocessrequiresapowerfulpost-processingsoftwaretobuildthemodel.Themodelingprocessmainlyincludestwotasks,roughmodelingandtexturemapping.Theformertaskistoconstructatriangularmeshsurfaceoftheprocessedpointclouddatabasedonthenearestprinciple,sothattheentireoutlineisnotonlyclosetothetargetprototype,butalsothenthroughthemethodofsurfacefitting,therepairsandsmoothingarerepeatedlyrepeatedtocompletetheconstructionofthree-dimensionalmodels.Three-dimensionalModelConstruction三维模型构建后者为了使生成的三维模型看起来更具有逼真的效果，需要对模型进行纹理映射。这里需要利用事先采集目标物体的表面图像，获得其纹理图像，然后将得到的纹理图像与建立的三维模型进行重合和叠加，使得三维图像接近更加立体和形象。Thelattertaskistomakethegeneratedthree-dimensionalmodellookmorerealistic.Texturemappingisrequired.Asurfaceimageofthetargetobjectiscollectedbeforehandtoobtainitstextureimage,andthentheobtainedtextureimageissuperimposedandoverlaidontheestablishedthree-dimensionalmodeltomakethethree-dimensionalimageclosertoamorethree-dimensionalandrealisticimage.01土石方体积测量VolumeMeasurementofEarthandStone土石方工程是建设工程施工中的一项重要工作。三维激光扫描技术凭借着高效采集大量点云数据的优势，可以快速地完成土石方数据的采集工作，运用相应的后处理软件可以有效地建立立体模型，从而精确地计算得出所测区域的土石方量。Earthandstoneengineeringisanimportanttaskinconstructionengineering.Withtheadvantagesofefficientdatacollectionoflargepointclouddata,three-dimensionallaserscanningtechnologycanquicklycompletethedatacollectionofearthandstone,andbyusingthecorrespondingpost-processingsoftware,itcaneffectivelyestablishathree-dimensionalmodel,therebyaccuratelycalculatingthevolumeofearthandstoneinthemeasuredarea.三维激光扫描技术的应用TheApplicationofThree-dimensionalLaserScanningTechnology02历史建筑保护HistoricalBuildingPreservation采用三维激光扫描仪对某历史建筑进行数据采集，便可以得到历史