无网格DEM构建关键技术研究

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1、南京师范大学博士学位论文无网格DEM构建关键技术研究姓名：朱莹申请学位级别：博士专业：地图学与地理信息系统指导教师：刘学军20090517摘要5．研究了基于无网格法进行地形因子与流域网络的提取。根据无网格法中导数求解方法和现有坡度坡向求解公式，给出了各点坡度坡向的计算方法。研究微分几何中主曲率与主方向的求解方法，以及地形中汇水线的数学性质，给出了提取汇水线上特征点的方法。研究将提取的特征点连接成为汇水线网络的方法。本研究通过无网格法构建一种灵活可变的散点结构的DEM，采用曲面模型的地形表达方法。解决了网格所带来的限制，为无网格法应用于地学模型提供了基础。关

2、键词：数字高程模型无网格法重构核近似支撑域断线形函数ⅡAbstraetAbstractAsoneofthemostimportantfundamentalgeographicdatainGIS，DEM(DigitalElevationModel)isthedigitalexpressionoflocalrelief,whichusesscatteredpointstosimulatecontinuoustopographicalsurface．DTA(DigitalTerrainAnalysis)istopographicinformationproces

3、singtechnologywhichisusedtocalculatetopographicattributesandextractfeaturesbasedonDEM．DEMandtheresultsfromDTAprovidetopographicparametersforvariousgeographymodels．TerrainfeaturesCallbedepicted，analyzedandextractedthroughDEM，andthesearethefundamentalmaterialsandbasicinformationfore

4、arthscience．AlthoughDEMplaysanimportantrole，、jl，itllmorefocusonGISandgee-scienceanalysis，GridGISdatausuallyrepresentsinconsistent埘mgeographymodels，whichresultsingridproblemsandalsoscaleeffect．ThemostrepresentativeproblemisMAUP(ModifiableArealUnitProblem)inecology．Meshfreemethoddoe

5、sn’tneedpredefinedgridinformationtodiseretizedomainwhensettingupthemodelofentireproblemdomain．Meshfreeapproximationisconstructedbynodes，SOithasadvantagesinsolvinggreatdeformationanddynamicdiscontinuityproblems．Thismethodisflexible，andnodesCanbeaddedordeletedfreelyduringcalculation

6、,soit’Seasytoachieveadaptiveanalysisandalsohigllcalculationaccuracy．MeshfreemethodprovidesanewwayforDTA．Topographyexpressionandterrainanalysisbasedonmeshfreemethodhavebeenthefoundationforsolvinggridproblems，providingfurtherpossibilitytoapplymeshfreemethodtogee·sciencemodels．Thisst

7、udyintroducesmeshfreemethodtoconstructDEMandappliesittoDTA，themainresearchesandinnovationsareasfollows：1．Meshfreemethodanditsapproximationsaresystematicallyreviewedandanalyzed，thecharacteristicsofmeshfreeapproximationconstructingmethodarelearned，andtheirsuitabilityforterrainexpres

8、sionisanalyzed．2．Adaptivemethodof