简介:Theresearchworkhasbeenseldomdoneaboutcloverleafjunctionexpressionina3-dimensionalcitymodel(3DCM).Themainreasonisthatthecloverleafjunctionisofteninacomplexandenormousconstruction.Itsmainbodyisbestraddleinair,andhasaerialintersectionsbetweenitsparts.Thiscomplexfeaturemadecloverleafjunctionquitedifferentfrombuildingsandterrain,therefore,itisdifficulttoexpressthiskindofspatialobjectsinthesamewayasforbuildingsandterrain.Inthispaper,authorsanalyzespatialcharacteristicsofcloverleafjunction,proposeanall-constraintpointsTINalgorithmtopartitioncloverleafjunctionroadsurface,anddevelopamethodtovisualizecloverleafjunctionroadsurfaceusingTIN.Inordertomanagecloverleafjunctiondataefficiently,theauthorsalsoanalyzedthemechanismof3DCMdatamanagement,extendedBLOBtypeinrelationaldatabase,andcombinedR-treeindextomanage3Dspatialdata.Basedonthisextension,anappropriatedatastructur
简介:老师说:“豆豆,你来回答这个问题:秦始皇灭六国的先后顺序是什么?”豆豆回答:“韩赵魏楚燕齐。”老师说:“不错,和同学们说说你是怎么背的吧。”豆豆说:“喊赵薇去演戏。”
简介:标准名称:ASTMD5772–15StandardTestMethodforCloudPointofPetroleumProducts(LinearCoolingRateMethod)ASTMD5772–15石油产品浊点的标准试验方法(线性冷却速率法)说明:对于石油产品和生物柴油,浊点是某些用途时能有效使用的最低温度指标。太多的蜡晶