简介:Thelinecartographicsymbollocatedontheboundaryandthepointcartographicsymbollocatedbysinglepointarethemainbodyandstressofthemap.Thecartographicsymbolsaredividedintopoint,lineandareasymbolincartographyandtraditionaleducationalbooks,butuptonowthereisonlyqualitativedescriptionaboutthethreekindsofsymbols,therearenotthemathematicaldefinitionsofpoint,lineandareasymbols.Thispapertriestosolvetheproblem.Theauthorsproposethemathematicaldefinitionaboutpoint,lineandareacartographicsymbolaccordingtothetheoryoftopologyandexpoundtheirdependencerelation.
简介:ThispaperdiscussestheapproachesforautomaticalsearchingofcontrolpointsintheNOAAAVHRRimageonthebasisofdatarearrangementintheformoflatitudeandlongitudegrid.Thevegetationindextransformationandmulti-levelmatchingstrategieshavebeenproveneffectiveandsuccessfulastheexperimentsshowwhilethecontrolpointdatabaseisestablished.
简介:静态、运动学的testings被使用IGS5min,30年代和5s间隔调查在精确的点放的精确卫星钟产品(PPP)答案。测试结果证明IGS卫星钟的采样率在静态的PPP答案上有很小的效果。精确卫星钟的采样间隔的所有三种类型能满足放精确性的公里厘米水平;更高的采样率没为PPP答案有重要改进。然而,卫星钟的采样率在运动学的PPP在PPP答案上有重要影响。越高卫星钟的间隔,精确性完成了越多更好。运动学的PPP的精确性完成了由用30s间隔,精确卫星钟被使用精确卫星钟和30s间隔卫星钟能几乎生产的5min间隔被将近3050%关于答案改进运动学的答案的一样的精确性。而且,从不同分析中心的精确卫星钟产品的使用可以也差不多在PPP答案上生产效果。