三维建模毕业论文英文文献翻译.docx

三维建模毕业论文英文文献翻译.docx

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三维建模毕业论文英文文献翻译

毕业设计（论文）

文献翻译

ConstructingRulesandSchedulingTechnologyfor3DBuildingModels

ZhengweiSUI,LunWU,JingnongWENG,XingLIN,XiaoluJI

Abstract

3Dmodelshavebecomeimportantformofgeographicdatabeyondconventional2Dgeospatialdata.Buildingsareimportantmarksforhumantoidentifytheirenvironments,becausetheyareclosewithhumanlife,particularlyintheurbanareas.Geographicinformationcanbeexpressedinamoreintuitiveandeffectivemannerwitharchitecturalmodelsbeingmodeledandvisualizedinavirtual3Denvironment.Architecturalmodeldatafeatureswithhugedatavolume,highcomplexity,non-uniformrulesandsoon.Hence,thecostofconstructinglarge-scalescenesishigh.Meanwhile,computersarelackofprocessingcapacityuponalargenumberofmodeldata.Therefore,resolvingtheconflictsbetweenlimitedprocessingcapacityofcomputerandmassivedataofmodelisvaluable.Byinvestigatingthecharacteristicsofbuildingsandtheregularchangesofviewpointinvirtual3Denvironment,thisarticleintroducesseveralconstructingrulesandschedulingtechniquesfor3Dconstructingofbuildings,aimingatthereductionofdatavolumeandcomplexityofmodelandthusimprovingcomputers’efficiencyatschedulinglargeamountofarchitecturalmodels.Inordertoevaluatetheefficiencyofproposedconstructingrulesandschedulingtechnologylistedintheabovetext,theauthorscarryoutacasestudyby3DconstructingthecampusofPekingUniversityusingtheproposedmethodandthetraditionalmethod.Thetworesultsarethenexaminedandcomparedfromaspectsofmodeldatavolume,modelfactuality,speedofmodelloading,averagerespondingtimeduringvisualization,compatibilityandreusabilityin3Dgeo-visualizationplatforms:

ChinaStar,oneChina’sownplatformfor3DglobalGISmanufacturedbytheauthorsofthispaper.Theresultofcomparisonrevealsthatmodelsbuiltbytheproposedmethodsaremuchbetterthanthosebuiltusingtraditionalmethods.Fortheconstructingofbuildingobjectsinlarge-scalescenes,theproposedmethodscannotonlyreducethecomplexityandamountofmodeldataremarkably,butcanalsoimprovingcomputers’efficiency.

Keywords:

Constructingrules,Modelscheduling,3Dbuildings

I.INTRODUCTION

Inrecentyears,withthedevelopmentof3DGIS（GeographicalInformationSystem）softwarelikeGoogleEarth,Skyline,NASAWorldWind,large-scale3Dbuildingmodelswithregionalcharacteristicshavebecomeimportantformofgeographicdatabeyondconventional2Dgeospatialdata,likemulti-resolutionremotesensingimagesandvectordata[1].Comparedtotraditional2Drepresentation,geographicinformationcanbeexpressedinamoreintuitiveandeffectivemannerwitharchitecturalmodelsbeingmodeledandvisualizedinavirtual3Denvironment.3Drepresentationandvisualizationprovidesbettervisualeffectandvividurbangeographicinformation,andthusplaysanimportantroleinpeople'sperceptionsoftheirenvironment.Meanwhile,the3Dbuildingdataisalsoofgreatsignificancefortheconstructionofdigitalcities.

Buthowtoefficientlyvisualizethousandsof3Dbuildingmodelsinavirtual3Denvironmentisnotatrivialquestion.Themostdifficultpartofthequestionistheconflictsbetweenlimitedprocessingcapacityofcomputerandmassivevolumeofmodeldata,particularlyintheprocedureofmodelrendering.Takingthe3Dmodelingofacityfortheexampleusingtraditional3Dmodelingmethod,supposethereare100000buildingstomodelintheurbanareaandtheaveragesizeofmodeldataforeachbuildingisroughly10M.SothetotaldatavolumeofbuildingmodelsinthecitycouldreachaTBlevel.However,thecapacityofordinarycomputermemoryisonlyintheGBscale.Basedonthisconcern,theauthorsproposedtheschedulingtechnologyforlarge-scale3Dbuildingsmodelsinaspectsofmodelloadingandrendering.Duetothelackofbuildingconstructingrulesandstandard,modelsofbuildingsvaryinaspectsofconstructingmethods,texturescollectionandmodeldatavolume,especiallyinaspectsofmodelreusabilityandfactuality.Suchalargeamountofdatawithoutuniformconstructingrulesbecomesahugechallengefordatastorage,processingandvisualizationincomputers.Italsobringstheproblemofincompatibilityamongdifferent3DGISsystems.

AfteryearsofresearchinGIS（GeographicInformationSystem）,peoplehaveaccumulatedanumberofwaystosolvetheaboveproblems[3].Howeverinvirtual3Denvironment,becauseofthedifferenceindataorganizationandmannersofhumancomputerinteraction（HCI）,weneedtoapplyanewstandardizedmethodofmodelingandschedulingfor3Dmodels.Atpresent,thereisnosuchauniformmethodastheconstructingspecificationorstandardforthemodelingof3Dbuildings.Existingapproachesareinsufficientandinefficientintheschedulingoflarge-scalebuildingmodels,resultinginpoorperformanceorlargememoryoccupancy.Inresponsetosuchquestions,theauthorsproposedanewmethodfortheconstructionof3Dbuildingmodels.Modelsbuiltusingtheproposedmethodscouldbemuchbetterthanthosebuiltusingtraditionalmethods.Forthe3Dmodelingofbuildingobjectsinscenesoflargescale,theproposedmethodscannotonlyremarkablyreducethecomplexityandamountofmodeldata,butcanalsoimprovingthereusabilityandfactualityofmodels.Concerningtheschedulingoflarge-scalebuildingmodels,theModelLoadingJudgmentAlgorithm（MLJA）proposedinthispapercouldsolvetheoptimaljudgmentproblemofmodelloadingin3Dvisioncone,particularlyincircumstancewithuncertainuserinteractions.

Thispaperfirstexaminesandanalyzesexistingproblemsinconstructingandschedulingstepsof3Dbuildingmodels.Thentheauthorsproposeasetofconstructingrulesfor3Dbuildingmodelstogetherwithmethodsofmodeloptimization.Besides,specialschedulingtechnologyandoptimizationmethodformodelrenderingisalsoappliedinthispaperforlarge-scale3Dbuildingmodels.Inordertoevaluatetheefficiencyofproposedrulesandmethods,acasestudyisundertakenbyconstructinga3DmodelforthemaincampusofPekingUniversityandShenzhenusingboththeproposedmethodandthetraditionalmethodrespectively.Thetworesulting3DmodelsofPekingUniversitycampusandShenzhenarethenexaminedandcomparedwithoneotherinaspectsofmodeldatavolume,modelfactuality,speedofmodelloading,averagerespondingtimeduringvisualization,compatibilityandreusabilityinvarious3Dgeo-visualizationplatformslikeChinaStar（oneChina’sownplatformfor3DglobalGISmanufacturedbytheauthors）,Skyline,etc.Resultofcomparisontellsthatprovidedsimilarfactualityofmodels,usingtheproposedmethodofus,thedatavolumeofmodelswasreducedby86%;thespeedofmodelloadingwasincreasedby70%;theaveragerespondingtimeofmodelduringvisualizationandinteractionspeedwasreducedby83%.Meanwhile,thecompatibilityandreusabilityof3Dmodeldataarealsoimprovediftheyareconstructedusingourapproach.

II.MODELINGRULESOF3DBUILDINGS

3Dsceneisthebestformofvisualizationfordigitalcitysystems.Whileconstructing3Dmodelsforbuildingsobjects,propermethodsandrulesshouldbeused,whicharemadewithfullconcernsofthecharacteristicsof3Dbuildingmodels[2].Theresultingmodelsshouldberobust,reusableandsuitableenoughfortransmissionovercomputernetwork,andshouldatthesametimebeautomaticallyadaptedtosystemcapability.

Generallyspeaking,methodsofconstructing3Dbuildingmodelscanbeclassifiedintothreetypes:

wireframemodeling,surfacemodelingandsolidmodeling.Innormalcircumstances,tomodelbuildingsin3Dformat,theframeworkofbuildingshouldbeconstructedfirstaccordingtothecontourfeatures,numberoffloors,floorheight,aerialphotographandliveactionphotosofbuildings.Then,gatherthecharacteristicsofscenethatthebuildingstomodelarerepresenting.Importantcharacteristicsincludebuildingsaerialphotographorliveactionshootingphotos.Finally,mapthegatheredtexturetomodelframework,optimizethemodelandcreatedatabaseofthe3Dbuildingmodels.

Althoughtherehavealreadybeenmanyapproachesfortheconstructionof3Dbuildingmodels,aunifiedmodelingmethodandrulesarestillneededtoimprovetheefficiency,quality,facilitatechecking,reusabilityandarchivingofconstructedmodels.Byinvestigatingthecharacteristicsofbuildings,wefoundthatbuildingshaveregulargeometricsolidformodeling,similartextureonthesurfacesofdifferentdirections,highsimilarityinsmall-scalemodelsofbuildings,etc.Accordingtothese,thisarticlegivesadiscussiononthemodelingrulesfromthreeaspects,includingconstructingrulesofthe3Dbuildingmodels,texturemappingrulesof3Dbuildingmodelsandoptimizationmethodforconstructedmodelsbasedonmentionedconstructingrules.

A.Constructingrulesofthe3Dbuildingmodels

The3Dbuildingmodelingreferstotheprocedureofrepresentingtruebuildingsfromtherealworldintocomputerintheformof3Dobjects[4].Humanbeings,asthecreatorandatthesametimepotentialusersofmodels,playakeyroleinthisprocedure.Peoplearedifferentfromeachotherintheunderstandingofthebuildingobjects,methodsofmodelingandthesoftwaretoolstheyuseformodeling.Suchdifferencesamongpeoplewhocarryoutmodelingworkatthesametimeleadtothe3Dmodelsofdiversequalityandlowefficiency.Sothe3Dbuildingconstructingrulesproposedinthisarticlebecomenecessaryandhelpfultosolvetheaboveproblems.

1）Combinesimilarfloorsasawholeandkeeptheroofindependent

2）Sh