Digital马赛克

PolarimetricMosaickingofOrtho-RectifiedALOS/PalsarDataY.
Rauste,A.
Lnnqvist,H.
Ahola,M.
Molinier,andT.
HmeALOSPISymposium2008,Rhodes,Greece3-7November2008VTTTECHNICALRESEARCHCENTREOFFINLAND2IntroductionOneofthebenefitsofEarthObservationistheabilitytomaplargeareasatatimePolarimetricALOS/Palsarscenesarelimitedinsize(29kmswath)Bymosaickingseveralscenestogether,awideareacouldbemappedinasingleanalysisstepObjective:ToproduceamosaicofseveralpolarimetricALOS/Palsarscenesinsuchaformthatpolarimetricprocessingmethodslikepolarizationsynthesisandvariousdecompositiontechniquescanbeappliedtothemosaicproduct.
VTTTECHNICALRESEARCHCENTREOFFINLAND3StudySiteFirstplantousetheforestrystudysiteofHeinavesi(62o17'N,28o26'E)andaugmentthedatasetbyordering3additionalscenestoforma4-scenemosaic.
PolarimetricALOS/PalsarscenesdidnotoverlapatthelatitudeoftheHeinavesisite.
Newsite,basedonavailabilityofpolarimetricALOS/Palsardataandtheoverlapbetweenneighboringscenes.
InFinnishLapland,centre68o30'N,27o30'E.
FromlakeInaritoLokkareservoir,includingthetownofIvaloandIvaloairportwithitsmeteorologicalstation.
VTTTECHNICALRESEARCHCENTREOFFINLAND4ALOS/PalsarDataFourscenes:2fromorbit6327(2.
4.
2007,theeasternstrip)and2fromorbit6575(19.
4.
2007,thewesternstrip)Snow-meltingseasoninLaplandThetemperatureduringimageacquisitionwas-2oon2.
4.
2007and+3oon19.
4.
2007=>thesnowisdrier(withathinicecrust)intheeasternstripVTTTECHNICALRESEARCHCENTREOFFINLAND5DigitalElevationModelTheShuttleTopographicMappingmissionDEM(SRTMDEM)doesnotextendthisfarnorthDEMwaspurchasedfromtheNationalLandSurveyofFinlandTheDEM(25-mpixelspacing)hasbeenmadestartingwiththecontourlinesfromtopographicmapsat1:20000Elevationaccuracybetterthan2m110kmby60kminareaVTTTECHNICALRESEARCHCENTREOFFINLAND6PalsarGeo-codingAlgorithmEquationsbyCurlander(1982):Least-squaresformulation:Solutionfrom:Curlander,J.
1982.
LocationofspaceborneSARimagery,IEEETransactionsonGeoscienceandRemoteSensing,Vol.
GE-20,No.
3,July1982,p.
359-364.
VTTTECHNICALRESEARCHCENTREOFFINLAND7Ortho-Rectification-SoftwareFrameworkforExperimentation(Simplified)JAXApol.
prod.
L1.
1yrpalsarpolcal2s2yrpalsarpol2s2S2filesS2filesS2filesS2filesyrs2tocohavgyrortho5_grdT3filesT3filesT3filesT3filesT3filesT3filesT3filesT3filesT3filesT3filesT3filesT3filesT3filesT3filesT3filesT3filesT3filesRectifiedT3filesyrpalsargrid.
gdcfileDEMSorDblpol.
L1.
1yrpalsarsinglepolextractS2fileyrdetectfloat2i16yrortho4_grd16-bitfileRectified16-bitfileyrt3toamplVTTTECHNICALRESEARCHCENTREOFFINLAND8RadiometricCorrectioninStokesDomainGammacorrection:Pcorrected=(Pin-Pnoise)An/Aprojected+PnoiseAn=nominalprojectedpixelarea,Aprojected=actual,DEM-computedprojectedpixelareaAppliedtoStokesmatrixdataF(16elements,9independentelements):Fcorrected=(Fin-Fnoise)An/Aprojected+FnoiseAprojectedcomputedbya"pixel-counting"algorithmVTTTECHNICALRESEARCHCENTREOFFINLAND9PixelCountingAlgorithminRadiometricCorrectionThecentreofoutputpixelcentredwithaDEMelementGoingtowardsthesub-satellitepointinDEM,findthefirstDEMelementthatisoutsidetheslantrangeresolutionFindtheintersectionbetweenDEMsurfaceandrangeresolutionRepeatgoingawayfromthesub-satellitepointComputetheverticaldimensionxoftheprojectedpixelareaVTTTECHNICALRESEARCHCENTREOFFINLAND10ImageGeometryinMosaicking77tiepointsbetweenscenesbyimagecorrelation13GCPsbetweenscenesandmapsBlockadjustmentstatistics:RMSE/tiepoints:8.
9/9.
5m(N/E),maximum21.
9/31.
2mRMSE/GCPs:13.
6/19.
8m(N/E),maximum27.
5/38.
2mVTTTECHNICALRESEARCHCENTREOFFINLAND11OutlookforRadiometricCalibrationbetweenScenesOverlappingarea19April2007(left,+3o)and2April2007(right,-2o)AdifferenceinbackscatterlevelCleardifferencesindominatingscatteringmechanisms,especiallyinopenareasVTTTECHNICALRESEARCHCENTREOFFINLAND12VisualisationofPolarimetricMosaicMissingpixelsfilledwiththeaverageofthefirstpolarimetricscene(Fukuoka)Left:PolsarProPaulidecompositionRight:PaulidecompositionoutsidePolSARproMaskingofmissingpixelsQuantityshown:amplitude,notpowerofHH-VV,HV,andHH+VVHistogramclippingpercolour:0…98%VTTTECHNICALRESEARCHCENTREOFFINLAND13VisualisationofPolarimetricMosaic2MissingpixelsfilledwiththeaverageofthemosaicLeft:PolsarProPaulidecompositionRight:PaulidecompositionoutsidePolSARproMaskingofmissingpixelsQuantityshown:amplitude,notpowerofHH-VV,HV,andHH+VVHistogramclippingpercolour:0…98%VTTTECHNICALRESEARCHCENTREOFFINLAND14APerspectiveviewofthePolarimetricMosaicProducedwithGrassGISRed=HH+VV,Green=HV,Blue=HH+VVVTTTECHNICALRESEARCHCENTREOFFINLAND15APerspectiveviewofaLandCoverMapMountaintopsareopen/mineralLandcovermapcourtesyofFinnishEnvironmentInstituteSYKEVTTTECHNICALRESEARCHCENTREOFFINLAND16ConclusionsTechniquesexistforgeometricprocessingofpolarimetricALOS/Palsardataintohomogeneousmosaics.
Imagingduringsnow-meltingperiodcancausesignificantdifferencesbetweenneighbouringscenes.
Summer-timeimageacquisitioninaforestedregionisrequiredforafutureevaluationofcapabilitiesofpolarimetricALOS/Palsarmosaics.
VTTTECHNICALRESEARCHCENTREOFFINLAND17AcknowledgementsJAXAandESAforprovidingALOS/PalsardataintheESA/ADENprojectESA-3713SYKE(FinnishEnvironmentInstitute)forprovidingCORINEland-coverdataTEKES(FinnishFundingAgencyforTechnologyandInnovation)forfundingprojectNewSAR