简介:<正>所谓3S技术即GPS、GIS、RS技术。GPS(全球定位系统)是英文缩写词NAVSTAR/GPS(NAVigationSystemTimeAndRanging/GlobalPositioningSystem)的简称。全称应为“测时测距导航系统/全球定位系统”。GPS是由美国研制,并投入实际应用的最新卫星定位系统。其主要目的是为飞机和船舶导航定位。也可以用于其它多种目的。GPS技术已在航空、航天、航海、军事、地质、石油、勘探、交通、测绘等领域得到广泛的应用。美国于1993年6月26日已将GPS21颗卫星和3颗备用卫星全部发射入轨。
简介:Theproblemsoftheearth'sgravityfields'visualizationarebothfocusandpuzzlecurrently.Aimingatmultiresolutionrendering,modelingoftheEarth'sgravityfields'dataisdiscussedinthepaperbyusingLODalgorithmbasedonQuadTree.First,thispaperemployedthemethodofLODbasedonQuadTreetodivideuptheregionalgravityanomalydata,introducedthecombinednodeevaluationsystemthatwascomposedofviewpointrelatedandroughnessrelatedsystems,andtheneliminatedtheT-cracksthatappearedamongthegravityanomalydatagridswithdifferentresolutions.Thetestresultsdemonstratedthatthegravityanomalydatagrids'renderingeffectswereliving,andthecomputationalpowerwaslow.Therefore,theproposedalgorithmwasasuitablemethodformodelingthegravityanomalydataandhaspotentialapplicationsinvisualizationoftheearth'sgravityfields.
简介:ByusingobservedCHAMPorbitephemeredesandMSISE-90dryairmodelandregardingtheearthasasphereandanellipsoidrespectively,phasedelaysaresimulatedandthesimulateddataareretrievedunderdifferentschemes.Thecomparisonbetweentheinvertedtemperatureprofilesandthemodeltemperatureprofilesshowsthatbyinvertingobserveddata,wewillgettemperatureresultswithlargeerrorsiftheeffectofEarth'soblatenessisomitted.Thecorrectionmethodisprovedtobeeffectivebecausethetemperatureerrorsdecreasedobviouslywiththismethod.
简介:Theclassificationaccuracyofthevariouscategoriesontheclassifiedremotelysensedimagesareusuallyevaluatedbytwodifferentmeasuresofaccuracy,namely,producer'saccuracy(PA)anduser'saccuracy(UA).ThePAofacategoryindicatestowhatextentthereferencepixelsofthecategoryarecorrectlyclassified,whereastheUAofacategoryrepresentstowhatextenttheothercategoriesarelessmisclassifiedintothecategoryinquestion.Therefore,theUAofthevariouscategoriesdeterminesthereliabilityoftheirinterpretationontheclassifiedimageandismoreimportanttotheanalystthanthePA.ThepresentinvestigationhasbeenperformedinordertodetermineifthereoccursimprovementintheUAofthevariouscategoriesontheclassifiedimageoftheprincipalcomponentsoftheoriginalbandsandontheclassifiedimageofthestackedimageoftwodifferentyears.WeperformedtheanalysesusingtheIRSLISSIIIimagesoftwodifferentyears,i.e.,1996and2009,thatrepresentthedifferentmagnitudeofurbanizationandthestackedimageofthesetwoyearspertainingtoRanchiarea,Jharkhand,India,withaviewtoassessingtheimpactsofurbanizationontheUAofthedifferentcategories.TheresultsoftheinvestigationdemonstratedthatthereoccurssignificantimprovementintheUAoftheimperviouscategoriesintheclassifiedimageofthestackedimage,whichisattributabletotheaggregationofthespectralinformationfromtwicethenumberofbandsfromtwodifferentyears.Ontheotherhand,theclassifiedimageoftheprincipalcomponentsdidnotshowanyimprovementintheUAascomparedtotheoriginalimages.