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1、矢量河网渐进式传输方法研究AbstractProgressivetransmissionisanewtypeofnetworktransmissionmodeonspatialdata.ItisanimportantresearchtopicinGISatpresent.Progressivetransmissionachievesthattransmissionsynchronizewithdisplay.Itnotonlyfollowsthecognitivelawofhumanbeingsfromcoarsetofinefo
2、rm,butalsoshortensthewaitingtimeforusers,andrealizestheinteractionwithusers.Itisaneffectivemethodtosolvethecontradictionbetweenthelimitednetworkbandwidthandtransmissionanddisplayofmassivedata.Geographicinformationsystemsexisttwotypesofspatialdata,i.e.rasterandvector.T
3、hedatastructureofrasterdataisrelativelysimple.Progressivetransmissionbasedonrasterdatastudieshavebeenrelativelymature,andachievedremarkableresults.Vectordatahasitsowndiversityandcomplexity.Theresearchofprogressivetransmissionisnotyetmature.Therearestillmanyproblemsnee
4、dtobesolved.Studyonprogressivetransmissionofvectordatamainlyfocusesonthreeaspectsthatincludingprogressivetransmissionframe,vectordatageneralization,dataorganizationmethodbasedonmultiresolution.Thispapercarriedonthethoroughanalysisandresearchfromtheangleofcompressionan
5、dorganizationofcurvewiththeriverelementsastheresearchobject,proposeamethodforcurvecompressionanddataorganization,basedonthetheorythatutilizeaxistodividebend,whichappliestoprogressivetransmission.Thebasicideaisthat,firstofall,theendpointconnectionastheinitialaxisofthec
6、urve,accordingtothescreeningthresholdofthecorrespondingaxistoscreeningbendsandextractnodeandthefeaturepointsaremaintained.Later,accordingtothetypeofcombinationofadjacentbendstogeneratenewaxesandextractnodesfromthescreeningofbending.Afterthat,itutilizemultitreetorecord
7、extractiondata,andadjustthemultitreeinordertoensuretherationalityofcurveprofile.Finally,inordertoimprovetheefficiencyofdataretrieval,storagenodedatalinearly.Themethodtakesintoaccountthehierarchicalcharacteristicofcurvefromtheangleofcompositebends.Itnotonlymaintainsthe
8、topologicalrelationofspatialelements,butalsorealizesmultiscaleexpressionofvectorrivernetworkingeometricdetaillayer.Multiscal
