三维建模毕业答辩论文英文文献翻译.docx
《三维建模毕业答辩论文英文文献翻译.docx》由会员分享,可在线阅读,更多相关《三维建模毕业答辩论文英文文献翻译.docx(11页珍藏版)》请在冰豆网上搜索。
三维建模毕业答辩论文英文文献翻译
三维建模毕业答辩论文英文文献翻译
毕业设计(论文)
文献翻译
题目矿山测量三维模型制作
学院测绘科学与技术学院
专业测绘工程
班级0802班
学生史姝
学号0810020205
指导教师汤伏全
二〇一二年六月二日
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.Sothe3Dbuildingconstructingrulesproposedinthi