中波红外高光谱仿真中的辐射影响模型

LiBo,WangXiangfeng,SunLina,CuiYan(ShenyangInstituteofEngineering,Shenyang110136,China)

Abstract:InordertoimprovethefidelityoftheIRhyperspectraltargetcharacteristicsimulation,aninfluencemodelwaspresentedinthispapertocalculatetheinfluenceofthenearbybuildingonthetargetfinalradiationatcertainwavelength.Avirtualexperimentscenewasconstructedwith1976U.S.standardatmosphere.Simulationexperimentsweredonebasedontheconstructedvirtualscenein3.0-5.0滋matintervalsof0.01滋m,andthecalculationresultswerecomparedwiththetargetreflectedsolarradiationandthetargetself-radiation.Experimentsresultsshowthattheradiationinfluencefromthebuildingarehigherthanthetargetreflectedsolarradiationorthetargetself-radiationatsomewavebandranges,whichmeanstheradiationinfluenceisthemostcriticalradiationinsomeimagesoftheimagecube.Itprovestheinfluencemodelpresentedinthispaperisnecessaryandimportantinhyperspectralsimulation.Throughtheanalysisofsimulationresults,thebuildingsurfacetemperature,atmospheretransmittanceandthevalidradiationareaaredeterminedtobethe3keyfactorstoaffecttheinfluenceradiationofnearbybuilding.Keywords:radiationinfluence;CLCnumber:TJ765atmospheretransmittance;reflectance;reflectedsolarradiationDocumentcode:ADOI院10.3788/IRLA201847.0304003中波红外高光谱仿真中的辐射影响模型李波，王祥凤，孙丽娜，崔妍(沈阳工程学院,沈阳辽宁110136)摘要院为提高红外高光谱目标特性仿真的逼真度，提出了一种辐射影响计算模型，用于计算目标周围的建筑物对目标的最终辐射特性的影响。建立了一个虚拟实验场景，设定场景的大气环境为1976年的美国标准大气。在建立的虚拟场景上在中波红外3.0~5.0滋m范围内以0.01滋m为步长对目标所受的辐射影响进行了仿真计算，并将辐射影响与太阳辐射、目标自身辐射进行了比较。实验结果显示在中波红外的某些波段范围内，相邻建筑单位面积的辐射影响亮度要高于太阳辐射亮度和目标自身辐射亮度。这表明在图像立方体的某些图像中，辐射影响是成像的最主要的辐射源，证明了多光谱/高光谱仿真情况下该模型的必要性和重要性。通过对仿真结果的分析，确定了建筑表面温度、大气透过率和有效辐射面积是辐射影响因素中的三个关键因素。关键词院辐射影响；大气透过率；反射率；反射的太阳辐射收稿日期院2017-10-10曰基金项目院作者简介院通讯作者院修订日期院2017-11-20(2015020020)曰(L2015368,L201602,LQN201709,L15BGL035)曰(18-015-7-29)

袁袁袁袁袁遥遥Email:lbian@126.com

(1980-)袁(1981-)袁0304003-1

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第3期www.irla.cn第47卷0IntroductionWiththeapplicationanddevelopmentofinfraredbecomeimagingthenewtechnology,generation[1-3]

simulationshouldnotusethewayoftraditionalIRsimulationdirectlybecauseoftheignoranceoftinywavebandrangcharacteristic.Aradiationinfluencemodelforthehyperspectraltargetradiationcharacteristictheofinfraredmultispectral/hyperspectralimagingtechnologyhasphotoelectricdetectiontechnology,andhasbeenwidelyusedsimulationisproposedinthispaper.Themodelisusedtocalculatetheradiationinfluenceonthetargetradiationfromanearbybuildinginthewavebandrangof3-5滋matintervalsof0.01滋mbasedonavirtualscene.Thecalculationresultsshowtheradiationdifferencesamongtinywavebandsandtheimportanceandnecessityoftheradiationinfluencemodel.Theresearchworkinthispapershowsthatsomefactorswhichneedn忆ttobeconsideredinthewidewavebandsimulation(like3.0-5.0滋m)couldbeveryimportantwhichcandecidewhetherthesimulationresultiscorrectinsometinywaveband.TheresulthasveryimportantguidingmeaningtothedeterminationofnecessaryfactorsintheIRhyperspectralsimulation.inmanyfieldssuchasmilitary,agriculture,industry,biologyandsoon.ComparedwithtraditionalIRimages,thehyperspectralimagescanprovidemoreinformationinformofimagecube,whichmergesthespatialinformationandspectralinformation.Inthe[4]

developmentofrelevantinstruments,equipmentsandthevalidationofrelevantalgorithm,plentyofhyperspectralimagesareneeded.Theimagesacquiredfromrelevantequipmentsareexpensive,anditisimpossibletocaptureimagesinvariousmeteorologicalenvironmentontheotherhand.Asaresult,theinfraredhyperspectralsimulationtechnologyhasbecomeanewresearchhotspot.Theinfraredhyperspectralsimulationtechnologyisdevelopedfromtraditionalinfraredsimulationtechnology[5].Theimagesfromtraditionalinfraredsimulationtechnologyfocusontheoverallradiationstatusofawidewavebandrangelike3-5滋mand8-12滋m,whichignoretheradiationcharacteristicofeverysingletinywavebandrangelike3.04-3.05滋mand9.25-9.26滋m,whilethehyperspectralradiationimagescanexactlytinyshowthedifferencesbetweenwaveband员EstablishmentofthemodelThemainfactorsforthetargetradiationcharacteristicsimulationinthetraditionalIRsimulationarethetargetself-radiationandthereflectedradiationofthetargetfromenvironment,whiletheenvironmentradiationincludingthesolarradiation,theatmosphereradiationandthegroundradiationisshowninformula(1):Lobj()=Lobjself()+Lrsun()+Lrground()+Lrsky()simulatethetargetcharacteristicin(1)theTheformula(1)isnotpreciseenoughtohyperspectralsimulationbecauseoftheignoranceoftheradiationinfluence.Forexample,ifthetargetisbeyondabuilding,thebuildingwillinfluencetheradiationcharacteristicofthetarget.Theinfluenceeffectisespeciallyobviousinhyperspectralsimulation,andcan爷tbeshownbyformula(1).ranges.Theradiationdifferenceshaveimportantsignificanceinmanyfieldssuchastargetdetectionandidentification,IR-counter-countermeasures[6]andsoon.Atthemeantime,thehyperspectralsimulationrequiresmuchmoreprecisedata,becauseanytinydatanoisemayinfluencetheeffectofthesimulationimages.Therefore,asmanyaspossiblefactorsshouldbeinvolvedinthehyperspectralsimulation[7]

.Andthehyperspectral0304003-2

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第3期www.irla.cn第47卷AvirtualsceneisconstructedasshowninFig.1.Thereisatargetinthescene,whosesurfaceisthegroundradiationtheatmosphereradiationareignoredinthispaper.AsshowninFig.1,theradiationinfluenceofthetargetwhichcanbecalculatedbyformula(3)ismainlyfromtheself-radiationofthenearbybuildingandthereflectedsolarradiationofthenearbybuilding.Linfl()=Lrb()+Lrbsun()(3)WhereLrb()isthetargetreflectedradiationfromFig.1Virtualscene

nearbybuilding,andLrbsun()isthetargetreflectedradiationfromthenearbybuildingreflectedsolarradiation.Intheprocessofradiationtransmission,theatmospherewillresultinanabsorptionlosstotheradiation.Thereflectedradiationofapointonthetargetfromperunitareaofthenearbybuildingcanbecalculatedasinformula(4),whichisrelatedtotheatmospheretransmittanceandthereflectivityofthematerialoftheouterwallofthebuilding.Lrbu()=Lbp(,T)伊()伊r()WhereLbp(,T)istheradianceofwavebandtemperatureTofaunitvalidradiationarea,istheatmospheretransmittanceatwavebandandrmadeofaluminiumalloy.Aconcretebuildingislocated100mfarfromthetarget,whoseouterwallisroughenoughtoworkasaLambertreflectingplane.Settingtheatmosphereofthevirtualsceneis1976USstandardatmosphere,thewheatheriscleanandcalm,thevisibilityonthegroundis23km,theaerosolmodelofneargroundistypicalaerosolmodel.Thecloudeffectandconvectionisunconsideredinthevirtualscene.Thesunisinthe200thdayinayear,thezenithangleandazimuthangleare30毅.AllthereflectionbythetargetandthebuildinginthesceneissetasLambertianreflection.Inviewofthissituation,theinfluencecalculationmodelisproposedtoachievemoreprecisesimulationofthetargetcharacteristic.Lobj()=Lobjself()+Lrsun()+Lrground()+Lrsky()+Linfl()(2)WhereLinfl()isthecalculationitemoftheradiationinfluenceforthetargetfromnearbybuildings.Consideringthefactthatthesolarradiationandthetargetself-radiationaretwomostimportantitemsintheprocessofIRdetection,ifsomeradiationcouldbecomparedtothistworadiation,thentheradiationshouldnotbeignored.Inordertodescribetheimportanceoftheradiationfromnearbybuildings,theresearchofthezerostadiaradiationcharacteristicofthetargetismainlyfocusedonthesetwofactors,and(4)at(),()isthereflectanceofthetargetsurfaceat.wavebandForanypointPonthetargetsurface,thetotalradiationfromthenearbybuildingisrelatedtothevalidradiationareaforpointP,asshowninFig.2.ThetotalradiationPreceivedcouldbedescribedinformula(5):Lrb()=乙S0

Lrbu()ds=乙S0

Lbp(,T)伊()伊r()ds(5)Fig.2ValidradiationareatoP

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第3期www.irla.cn第47卷WhereSisthevalidradiationareatopointP.Assumingtheouterwallofthenearbybuildingislambertbodybecauseofitsroughness,whichmeansthesolarradiationreflectedbytheouterwallhasthesameintensityatalldirection.Thebuildingreflectedsolarradiationwillbereflectedbythetargetsurface,aftertheabsorptionoftheatmosphere,andfinallyachievethesensor.TheradiationfromaunitvalidradiationareareceivedbypointPonthetargetsurfacecouldbedescribedasformula(6):Lrbsunu()=Lsun()伊b()伊()伊r()WhereLsun()isthesolarradiance,andatwaveband.b

relatedtothesurfacetemperatureTandtheemittancewavelength()ofthesurfacematerialat.AccordingtoPlancklawofblack-is:c2Tbodyradiation,theradiationexitanceofblack-bodyoftemperatureTatwavelengthMblack(,T)=Wherehis5the蓸e2仔hchckT2

-1Planck蔀c1

蓘蓸e5

-1k蔀蓡is(9)the2

constant,Boltzmannconstant,cisthespeedoflight,andTisthethermodynamictemperature.c1=2仔hc=3.7418伊10-16(W窑m2)andc2=hc=1.4388伊104(滋m窑K)karecalledthefirstandsecondradiationconstant.Theradiationexitanceofcommonisbodywhoseemittanceatwavelengthcalculatedasinformula(10):M(,T)=()伊Mblack(,T)Theradianceofthecommonbodyis:L(,T)=()伊Mblack(,T)/仔(11)Supposingthetransmittanceofconcreteouterwallandthetargetsurfaceareboth0,thentheemittanceofthematerialcouldbecalculatedbythematerialreflectancewhichcouldbeacquiredfromtheU.S.JPL(JetPropulsionLaboratory)ASTERSpectralLibrary[8]asinformula(12):()=1-()(12)Thereflectanceofaluminiuminwaveband3.0-5.0滋mfromASTERSpectralLibraryisshowninFig.3,andthecorrespondingemittanceisshowninFig.4.(10)()couldbe(6)()isthematerialreflectanceofthebuildingouterwallTheradiationamountreceivedbypointPisrelatedtothevalidradiationareaofthenearbybuildingtoP.TheradiancePreceivedfromthenearbybuildingreflectedsolarradiationcouldbedescribedasformula(7):Lrbsun()=Thefinal乙S0

Lsun()伊b()伊()伊r()dsinfluence(7)radiationcalculationformulaofpointPcouldbederivedbyformula(3)-(7)asformula(8):Linfl()=2SimulationcalculationForsimulation,theatmosphereofthevirtualsceneissetasU.S.standardatmospherein1976,dateisearlyinJuly,sunnywith30毅solarzenithangle,ignoringtheabsorptioneffectfromaerosolsorclouds.Assumingthematerialofthetargetsurfaceisaluminium,thematerialofbuildingouterwallisconstructionconcrete.Thesurfacetemperatuerofboththetargetandthebuildingis300K.Thesimulationcalculationisdoneinwaveband3.0-5.0滋m.圆.1Self-radiationofthetargetTheself-radiationoftargetatwavelengthis0304003-4

乙S0

(Lbp(,T)+Lsun()伊b()ds伊()伊r()(8)Fig.3Reflectanceofaluminiumin3.0-5.0滋m

红外与激光工程

第3期www.irla.cn第47卷Fig.4Emittanceofaluminiumin3.0-5.0滋m

Accordingtoformula(11),thecalculationresultofself-radianceofthetargetat300KisshowninFig.5.Fig.6Solarirradiance

Fig.7Targetreflectedsolarradiance

2.3Targetreflectedself-radiationofbuildingFig.5Radianceofaluminiumin3.0-5.0滋m

Thereflectanceofconstructionconcrete2.2TargetreflectedsolarradiationInthispaper,thesunisconsideredtobeaconstantlightsource.ThesolarradiationhasveryimportantinfluenceintheprocessBelowofisIRthehyperspectralradianceLrsun():Lrsun()=Lsun()伊r()=Isun()伊r()/仔couldbecalculatedbyModtran,wavelength.(13)WhereIsun()isthesolardirectirradiancewhichr

acquiredfromJPLASTERSpectralLibraryisshowninFig.8,andtheemittanceisshowninFig.9.simulation.computationformulaoftargetreflectedsolar()istheFig.8Reflectanceofconstructionconcrete

reflectanceofthetargetsurfacematerialatTheresultofthesolarirradianceforthescenecalculatedbyModtraninwaveband3.0-5.0滋misshowninFig.6.Accordingtoformula(13),thecalculatedresultoftargetreflectedsolarirradianceisshowninFig.7.Fig.9Emittanceofconstructionconcrete

0304003-5

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第3期www.irla.cn第47卷Thetemperatureofthenearbybuildingouterwallis300K.Accordingtoformula(11),thecalculationresultoftheself-radianceoftheouterwallisshowninFig.10.Fig.12Radiancefromoneunitofthenearbybuilding

Fig.10Self-radianceofthenearbybuilding

Incurrentatmosphere,theIRradiationFig.13Targetreflectedradiancefromoneunitof

thenearbybuilding

atmospheretransmittanceindistanceof100minwavebandrange3.0-5.0滋mcalculatedbyModtranisshowninFig.11.Accordingtothecalculationresults,thetransmittanceisextremelyhighinalmostallthewavebandrangeexceptfor4.2-4.3滋m,wherethetransmittancededucedto0rapidly.Figure11showsclearevidencethattheradiancefromthebuildingcanreachthetargetwithonlyatinyenergyloss.2.4TargetreflectedradiancefromthenearbybuildingreflectedsolarradianceAccordingtoformula(6),consideringthebuildingasaLambertbody,thecalculatedresultsoftargetreflectedradiancefromoneunitofthenearbybuildingreflectedsolarradianceisshowninFig.14.Fig.11Transmittancein100m

Fig.14Targetreflectedradiancefromthenearbybuilding

reflectedsolarradiance

ThecalculationresultsofradiancereachesthetargetfromoneunitofthenearbybuildingisshowninFig.12.Accordingtoformula(4),thetargetreflectedradiancefromoneunitofthenearbybuildingisshowninFig.13.2.5RadiationinfluencefromoneunitofthenearbybuildingAccordingtoformula(8),theradiationinfluencefromthenearbybuildingisrelatedtothebuildingself-radiationandthebuilding0304003-6

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第3期www.irla.cn第47卷reflectedsolarradiation.Thetotalradiationreflectedsolarradiationandthebuildingradiationinfluencetothetargetwhichiscombinedwiththereflectedbuildingself-radiationandthereflectedsolarradiationfromthebuildingtogetherinonesinglefigureasshowninFig.17.influencetopointPfromoneunitfornearbybuildingisshowninFig.15.Fig.15Totalradiationinfluence

Sofar,allthe4criticalfactorsinthescenewhichcaninfluencethetargetfinialradiationcharacteristicsarecalculated.Putthe4calculationresultstogetherforcomparisoninonesinglefigureasshowninFig.16.Thereflectedbuildingself-radiationandthereflectedsolarradiationfrombuildingaretheradiationinfluencetothetarget.Figure16showsclearevidencethatthesolarradiationisthemostcriticalfactorinthesceneinwavebandrange3.0-5.0滋m,whilethetargetself-radiationisataprettylowlevel.Thebuildingreflectedsolarradiationishigherthanthebuildingself-radiationinwavelengthband3.0-3.9滋m,whilethebuildingself-radiationismuchhigherthanthebuildingreflectedsolarradiationinwavelengthband3.9-5.0滋m.Fig.17Radiationcomparisoninthescene

Figure17showsthatthesolarradiationisdozensoftimestohundredstothetargetself-radiationinentirewavebandrange3.0-5.0滋m.That忆swhythetargetself-radiationcouldbeignoredintraditionalIRsimulationinwaveband3.0-5.0滋m.ButforhyperspectralIRsimulationwhichfocusesonthedifferencesinonesinglewavelength,thetargetself-radiationshouldnotbeignored.Forexample,inwavelength4.9滋m,thetargetself-radiationishigherthanthesolarradiation.Accordingtothecalculationresults,theradiationinfluencefromthebuildingandthesolarradiationinthevirtualsceneareatthesameorderofmagnitude.Inthewavebandrange3.0-4.4滋m,theradiationinfluenceisseveraltimessmallerthanthesolarradiation,whileitisbiggerin4.4-5.0滋m.Thecalculationresultsprovethattheradiationinfluenceismoreimportantthanthesolarradiationinsomewavelengthrange,andshouldbeseriouslyconsideredinthesimulationprocess.Fig.1criticalradiationfactors

猿.1InfluencewithchangesofthevalidradiationareaThecalculationresultsshowninFig.17aretargetbasedontheradiationfromonesingleunitfrom猿住nalysisofthesimulationresultsPutthetargetself-radiation,the0304003-7

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第3期www.irla.cn第47卷thenearbybuilding.Withtheincreaseofthevalidradiationarea,theinfluenceeffectbecomeslargerandlarger,andtheradiationfromthebuildingbecomesthemostimportantradiationinmoreandmorewavelengths.AsshowninFig.18,whendoublingthevalidradiationarea,theradiationfromthebuildingbecomesthemostimportantradiationin4.3-5.0滋m.Whentriplingthevalidradiationarea,theradiationinfluencebecomesthemostimportantradiationin4.2-5.0滋m.Whenquadruplingthevalidradiationarea,theradiationinfluencebecomesthemostimportantradiationin4.0-5.0滋m.influencesinAtthemeantime,theradiationotherwavebandareenhancedWhenthetemperatureishigherthan290K,theself-radiationofthebuildingisstrongerthanthesolarradiationin3.0-5.0滋m.Asthetemperatureincreases,theinfluencelevelimprovessignificantly.Fig.19Comparisonoftheradiationatdifferenttemperatures

obviously.Accordingtothecalculation,whenthevalidradiationareaincreasedby12times,theradiationinfluencewillbecomethemostimportantradiationin3.0-5.0滋m.Thestudyshowsthatsurfacetemperatureofthebuildinghasanobviouseffectontheradiationcharacteristicoftarget,andtheinfluenceeffectbecomestrongerinhyperspectralsimulationconditionsespecially.4ConclusionAimingatthecharacteristicoftheIRhyperspectralsimulationandbuildingsthataremadeofconcrete,theradiationinfluencemodelispresentedAndinthispaperforthearetargetdoneinIRacharacteristicsimulationwithanearbybuilding.Fig.18Radiationinfluencewithdifferent

validradiationarea

simulationexperimentsconstructedvirtualsceneinwavebandrange3.0-5.0滋m.Thesimulationexperimentsresultsshowthattheradiationfromthenearbybuildinghashugeinfluenceonthefinalradiationcharacteristicofthetarget.Thesurfacetemperatureofthenearbybuilding,thevalidradiationareaandthedistancefromthetargettothebuildingarecriticalfactorsforthetargetfinalradiationcharacteristic.Tosumupinconclusion,inIRhyperspectralsimulation,thenearbybuildingsofthetargetcancausehugeinfluenceonthetargetfinalradiationcharacteristicatsomewavelength.Thereforethenearbybuildingfactorshouldbeserially3.2InfluencewithchangesofthesurfacetemperatureofthenearbybuildingFigure19showsthecomparisonofthetargetreflectedself-radiationofthebuildingatdifferenttemperatureswiththetargetself-radiationandthetargetreflectedsolarradiationatonesingleunitradiationarea.Thefigurerevealsthattheself-radiationofthebuildingisnothigherthanthebuildingreflectedsolarradiationin3.0-4.2滋m,whiletheself-radiationismuchhigherthanthebuildingreflectedradiationinwaveband4.2-5.0滋mwhenthebuilding忆stemperatureislessthan290K.0304003-8

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第3期www.irla.cnconsideredinhyperspectralsimulation.Theradiationinfluencemodelpresentedinthispapercouldcalculatetheradiationinfluenceeffectivelyandprecisely.[5]

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