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1、PARTVIIITECHNICALAPPENDICESCHAPTER37GEOSPATIALDATADavidF.Maune,Ph.D.,C.P.‘‘Spatialdatadealswithlocation,shapesandtherelation-RasterDataandVectorDatashipsamongfeatures(topology).DescriptivedatadealswithRasterdataconsistsofgeoreferencedpixelsorgridcellsoftheattributesorcharacter
2、isticsofthefeatures.Thecombi-uniformresolution.Digitalimagesarerasterdata,asarenationofthetwotypesofdataisthekeytocreatingintel-mapsorengineerdrawingsscannedat500or1000dotsligentmaps.’’(ThePowerofMapsexhibit,SmithsonianInstitution)perinch(dpi),forexample.Apixel(pictureelement)
3、isthesmallestindivisibleelementofadigitalimage.OnepixelofINTRODUCTIONaLANDSATsatellitemultispectralimageequatestoa30-mby30-msquareareaontheground;1pixelofastandardGeospatialdataisinformationthatidentifiesthegeographicUSGSDigitalOrthophotoQuarter-Quad(DOQ)coversalocationandchara
4、cteristicsofnaturalorconstructedfea-turesandboundariesofearth.Thisinformationmaybe1-mby1-msquarearea;and1pixelofahigh-resolutionderivedfrom,amongotherthings,mapping,surveying,anddigitalorthophotoproducedspecificallyforalanddevel-remotesensingtechnologies.Geospatialdataandspatia
5、ldataopmentprojectmightcovera6-in.by6-in.areaonthearenormallyusedinterchangeably.However,spatialdataground.Suchimagesarereferredtoashaving30-m,1-m,couldincludethesize,relativelocation,and/orcharacter-or6-in.pixelsrespectively.Thisisalsocalledtheimageisticsoffeatureswithoutknow
6、ingtheirexactgeographicresolution.Theresolutionofscanneddocumentsisreferredlocation(e.g.,genericbuildingplansthatarenotgeorefer-tointermsofdpi.Rasterimagescanbedisplayedontheenced),whereasgeospatialdataisalwaysgeoreferencedincomputeratdifferentscales,tothepointwhere‘‘pixelterm
7、sofgeographiccoordinates(latitudeandlongitude)orbreakdown’’occursandindividualpixelsarevisible,butsomeformofrectangularcoordinates(normallyStatePlane‘‘zoomingin’’doesn’timprovetheaccuracyofsuchrasterorUTMcoordinates).data.LanddevelopmentengineersandsurveyorsneedtofullySomewhat
8、differentfromapixel,arastergridcellisoneunderstandgeospatiald
