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1、实验七ENVI软件介绍目的：初步认识遥感数字图像处理软件ENVI,了解ENVI的组成；掌握TM、ETM+数据的ENVI读取；认识ENV1的数据文件；掌握辐射亮度和反射率的计算。实验原理：关于头文件的解读，传感器记录的数据，遥感的基木物理量，辐射亮度与DN值之间的关系。UseLandsatTMcalibrationtoconvertLandsatTMorETMdigitalnumberstoradianceorcxoatmosphcricreflectance(reflectanceabovetheatmosphere
2、)usingpublishedpost-launchgainsandoffsets(seehttp://landsat7.iisgs.gov/cpf/cpf.phpandhttp://edcftp.cr.usgs.gov/pub/metadata/satellite/landsat7.tar.gz).Thespectralradiance(LI)iscalculatedusingthefollowingequation:whereQCAListhecalibratedandquantizedscaledradianc
3、einunitsofdigitalnumbers,LMIN1isthespectralradianceatQCAL=(),LMAX1isthespectralradianceatQCAL=QCALMAX,andQCALMAXistherangeoftherescaledradianceindigitalnumbers.LMIN1andLMAX1arcderivedfromtablesprovidedintheLandsatTechnicalNotes(August1986)withtheinformationprov
4、idedthroughtheTMCalibrationParametersdialoginENVI.QCALMAXis255forallTMdataand127forallMSSdataexceptBand4(0.8to1.1mm),whichis63forcertaintimeperiods(dataacquiredbeforeFebruary1,1979forLandsat1-3andprocessedbeforeOctober22,1982).Theresultingradiance(LI)isinunitso
5、fwattspersquaremeterpersteradianpermicrometer(W/(m2*sr*mm)).LMINL十LMAXZ-LMINZQCALMAXQCALTheexoatmosphericreflectance(rp)iscalculatedusingthefollowingequation:_兀・—・『=ESUN?-cosOswhereLIisthespectralradiance,distheEarth・Sundistanceinastronomicalunits,ESUN1isthemea
6、nsolarexoatmosphericirradiance,andqsisthesolarzenithangleindegrees・ESUN1isderivedfromtablesprovidedintheLandsatTechnicalNotes(August1986).Theresultingreflectanceisunitlcss-Seehttp://lanclsat.usgs.gov/documcnts/L5TMCal2003.pdfforfurtherdetails.TMband6,ifpresent,
7、isconvertedtotemperature.If7bandsareinput,the6thbandisassumedtobethethermalinfraredband.Ifonly6bandsareinput,thenitisassumedthatthereisnothermalinfraredband・ForLandsat7GcoTIFFfilesthatdonotcontaincalibrationcoefficients,youcanuseLandsatTMcalibrationtospecifythe
8、calibrationcoefficientsandotherrelatedparameters,oryoucanextracttheparametersfromaWebserver.实验数据与工具：ENVLETM+数据实验内容：1、ENVI简介ENVI(TheEnvironmentforVisualizingImages)遥感影像处理软件是美
