基于WebGIS的校园三维电子地图的设计与实现计算机毕业设计外文翻译.docx

基于WebGIS的校园三维电子地图的设计与实现计算机毕业设计外文翻译.docx

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基于WebGIS的校园三维电子地图的设计与实现计算机毕业设计外文翻译

TheDesignandImplementationof3DElectronicMapofCampusBasedonWEBGIS

I.INTRODUCTION

Nowadays,digitalizationandinformatizationarethethemeofourtimes.Withthedevelopmentofinformationrevolutionandcomputerscience,computertechnologyhaspenetratedintoallfieldsofscienceandcausedmanyrevolutionarychangesinthesesubjects,theancientcartographyalsocan'tescape.Withthetechnicalandculturalconstantlyprogress,theformandthecontentofthemapchangeandupdateaswell.Asthecomputergraphics,geographicinformationsystems（GIS）constantlyappliedtotheWeb,theconventionalwayoffabricationanddemonstrationhassufferedgreatchange,andtheapplicationoftheMaphasextendeddramaticallyowingtothedevelopmentofadvancedinformationtechnology.Underthesecircumstances,cartographywillbefacedwithpromisingprospect.Ithasbranchedoutintomanynewproducts.Oneoftheproductscomeintobeingisthee-map[1].Withtherapiddevelopmentofthecomputertechnology,computergraphicstheory,remotesensingtechnology,photogrammetrictechnologyandotherrelatedtechnology.Usersrequirehandlingandanalysisofthree-dimensionvisualization,dynamicinteractivityandshowtheirvariousgeo-relateddata,somuchattentionshouldbepaidtotheresearchofthreedimensionalmaps.ThisarticlebasedontheNortheastPetroleumUniversityanditssurroundingsdesignsandcreatesthethree-dimensionalelectronicmap.

II.FUNCTIONDESIGN

Three-dimensionalelectronicmapsystemofcampusbasedonWEBGIShasgeneralcharacteristicsofthecommonmaps.Throughpressingthearrowkeys（Up,Down,Left,AndRight）onthekeyboard,onecanmakethemapmovetowardsthecorrespondingdirectionoftranslation.Throughdraggingmouse,onecanseewhereverhelikes.Usingthemousewheel,youcancontrolamap'smagnitude,accordingtotheuser'sneedstoviewdifferentlevelsofmap.Thelowerleftofthemapwherewilldisplaythecurrentcoordinateofthemouseonthemap.Inadivlayer,wedepictahotspotofnewbuildings,thislayercanbedisplayedaccordingtothedifferentmaplayers,italsocanautomaticallyscale.Byclickingonhotspots,itcanshowthehotspot'sspecificinformation.Onecanalsotypeintothequeryinformationbasedonhisneed,andgetsomerelevantinformation.Inaddition,onecanchoosetocheckthethreedimensionalmapsandsatellitemapsthroughclickingthemouse.

Majorfunctions:

•Userinformationmanagement:

Checktheusernameandpassword,setlevelcertificationdependingonthepermissions,allowusersofdifferentpermissionstologinthesystemviatheInternet.

•TheinquiryofLocationinformation:

Systemcanprovideuserswithfuzzyinquiresandquicklocation.

•Mapmanagement:

Implementloadingmaps,mapinquires,layermanagement,andothercommonoperationssuchasdistancemeasurement,andmapszoom,eagleeye,labels,printing,andmore.

•Roamthemap:

Usetheupanddownkeystoroamanyareaofthemap,ordrag-and-dropdirectly.

III.THEPROCESSOFSYSTEMDEVELOPMENT

Tothefirst,wecollecttheinformationwhichcontainstheoutwardappearanceofarchitecturalbuildings,theshapeofthetreesthedesignoftheroads.Andthen,weconstructthreedimensionalsceneswith3DSMAXsoftware[2].Thatistosaywerenderthesceneandachievethehigh-defmitionmap,afterthatwecutthemapintosmallpictureswiththecutfigureprogram,atlastwebuiltthehtmlpageswhichcanasynchronousloadmapsandachievethefunctionoftheelectronicmaps.TheflowchartofthesystemdevelopmentwillbeshowninFigure1:

Figure1systemdevelopmentflowchart

Traditionalmapshavestrictrequirementsonmathematicallaws,mapsymbolsandcartographicgeneralizationwhenindesign.Theproductionofnetworklandscapeelectronicmapalsohasitsowntechnicalstandardswhichissuperiortothetraditionalmap.Thethree-dimensionalelectronicmaphasdifferentzoomlevels;thereforeitneedsnotthestrictscalebuttheunifiedproductionstandards.Mapsymbolusuallyimitatetherealworldasmuchaspossibleandsimplifyitselfatthesametime.Thescopeofthescreenisfargreaterthanthefixedvisionofpaperymaps.Cartographicgeneralizationsthinkmuchofthebalancebetweentheabstractmodelandtheactualperformanceresults.

Asforthedataacquisitionandmanagement,suchastheintroductionandtheinformationusersobtainedfromthemaparefinalresultsofdataacquisition.Inthebeginning,wecollecttheneededdataincludingthename,theaddress,theintroductionandthedigitalphotosofthebuildingsandprepareforthesubsequentthree-dimensionalmodeling.Aftercollectingthedata,weshouldpayattentiontoarchivalandbackupthefilesincaseofloss.

Inordertogetthemap,agoodpreparationofthedesignofthestandardsceneisnecessary.Wesettheparameteroftheunderlay,lights,altitudes,rendereffectsandsoon,soastoensurethefinalfruitofoureffortwillhaveauniformeffect.Thespatialentity'sperformancesusuallyshowupastheformofspot,lineandsurfaceinthethree-dimensionalelectronicmap.

Comparedwithvectorgraphics,thegridgraphicshaveunparalleledadvantages.ThecombinationofthegridgraphicsandtheWEBGIS'sbackgroundpublishingtechnologycanimprovetheresponsespeedofsystemandsavesystem'sinputs.SystemachievestheinteractionwiththemapwiththeJavaScriptlanguages.Seeingthatthereliedifferencesinsupportingthescriptinglanguagesonvariousbrowsers,testingallkindsoffunctionsbydifferentbrowsersisacrucialstep.

IV.KEYTECHNOLOGIES

Thedevelopmentsofthree-dimensionalelectronicmapsareinseparablewiththedevelopmentofrelatedareas,anditlearnsresearchmethods,techniquesandtoolsfromotherareas.Whiletheresearchesofotherareasaredirectlyappliedtothedevelopmentandconstructionofthree-dimensionalelectronicmap,andComputergraphics,3-DGIS,VirtualRealityandGeographicDataBase,themodelingofvirtualsceneandsobecamethetechnicalsupportofthethree-dimensionalelectronicmapsystem.

TheWEBGIStechnologyonwhichthree-dimensionalelectronicmapsystemofcampusbasedisastandardSoftwaretechnologywhichmeanswithoutanycommercialsoftware'ssupport.DuringthedevelopmentofthesystemwemakeuseofthecommonavailabletechnologywhichincludestheJavaScripttechnology,Ajaxtechnology,XMLtechnology,etc.

Ajaxisnotaonefoldtechnology,itisamixturewhichmixesmultipletechnologiestogether,includingthedocumentobjectwhichusedtodisplayonthewebanditshierarchicalstructuredocumentobjectmodelDOM,andCSSthatusedtodefinetheelementsofstyle,anddataexchangeformatXMLorJSON,implementationandasynchronousserverofXMLHttpRequestandclientscriptlanguageJavaScript[3].Ajaxtakesadvantageofnon-synchronousinteractiontechnologywhichmeansthereisnoneedtoupdatepages;therefore,itwilllessentheuser'swaitingtimebothpsychologicallyandphysically.Thatiswhyitwillbeeasiertobeacceptedbypublic.

EXTisanexcellentAjaxframeworkwritteninJavaScript;ithasnothingtodowiththeback-endtechnologyandcanbeusedtodeveloprichclientapplicationswithagorgeousappearance.ThesystemenablestheEXTcombinedwithJSPtoachievetheotherpagefunctionsoftheelectronicmap.ThesystemcombinestheEXTwiththePrototypewhoseframeworkbearstheburdenofcreatingarichclientandahighlyinteractiveWebapplication,whichrealizestheapplicationoftherichclientefficientlyandmanagethesafetyoftheclientinasafewaythatcouldbecontrolled.

JavaScriptistheprincipletechnologyofthesystemduringthedesignandtheimplementationprocess.Itallowsavarietyoftaskswhichcanbecompletedsolelyontheclient,andwithouttheparticipationofthenetworkandserverwhichusedtosupportthedistributedcomputingandprocessing,andthereforereducingtheinvisiblewasteofresources.JavaScriptallowsneithertheaccesstothelocalharddisk,northedatatobesavedtotheserver,letalonetomodifyanddeletenetworkdocuments.ThesinglewaytobrowsetheWebinformationandrealizedynamicinteractionisthroughthebrowser,whichcaneffectivelyguardagainstthedata-loss,consequentlythesystemreachesahighsecuritycoefficient.JavaScriptcanbeusedtocustomizethebrowseraccordingtothediverseusers,themoreuser-friendlythedesignofwebpagesis,theeasierthemethodfortheuserstomaster.JavaScripttechnologymeansthroughthesmall-blockapproachtorealizetheprogramming.Justastheotherscriptinglanguages,JavaScriptisalsoaninterpretedlanguage;itoffersaconvenientdevelopmentenvironment.

Inthissystem,wetakeadvantageofJavaScriptscriptinglanguagetorealizethekeyfunctionssuchasloadingmaps,zoomingmaps,geographiclocation,andotherrelatedauxiliaryfunctions,i.e.mapicondisplay,ranging,eagleeye,tags.Oracledatabasemeetstheneedofthedatawhichisusedinbackstagemanagement,andtogetherwiththeJSP,XMLandHTMLtorealizetheuser'sauthenticationaswellasadding,deleting,revisingandinquiringinformation’s,etc.

ThemainfunctionofthesystemistorealizethethreedimensionalelectronicmapdisplayedinthebrowserthroughWEBGIStechnology.OwingtothecombinationofJavaScripttechnologyandWEBGISdevelopmentmodel,wecanreducethecostofthesystem,andatthesametimeimprovetheinteroperabilityandsystemperformance.ThankstotheapplicationofAJAXtechnology,wecanmakefurtherimprovementonloadingdynamicalmap.Allthetechnologiesweusewillreducethereactiontime,whichwillleaveaquickandeffi