sinusoidal vs. geographic projec6on · sinusoidal vs. geographic projec6on nima pahlevan 1,2,...

SinusoidalVs.GeographicProjec6on

NimaPahlevan1,2,SudiptaSarkar1,2,VirginiaKalb2,EricVermote2,SadashivaDevadiga1,2,,GaryLin1,RobertE.Wolfe2,

MiguelRoman2,andChrisJus6ce3

1Science,Systems,AndApplica6ons,Inc.(SSAI)2NASAGoddardSpaceFlightCenter(619)

3DepartmentofGeographicalSciences,UniversityofMaryland

MODIS/VIIRSScienceTeamMee1ng,LandbreakoutSilverSpringMD

June2016

Introduc6on

•  Sinusoidalprojec6onwasadopted…–  Itwasrecommendedbyclimatemodelers–  Itpreservesthearea–  Thereislessdistor6onovertropicalareas–  Thereislesscomputa6onoverhigh-la6tudeareas

•  Geographicprojec6on,ontheotherhand,facilitateseasierintegra6onwithvariousgeo-visualiza6ontoolsavailablenowadays

2ImpactsofProjec6onChangeonLandProducts-NimaPahlevanSSAI/NASAGSFC

SinusoidalProjec6on

3ImpactsofProjec6onChangeonLandProducts-NimaPahlevanSSAI/NASAGSFC

RasterMosaicDatasetfromscaledEVITOC,defined'nodata’,withunderlyingshadedreliefDEMat30arcseconds(USGS)

GeographicProjec6on

4ImpactsofProjec6onChangeonLandProducts-NimaPahlevanSSAI/NASAGSFC

RasterMosaicDatasetfromscaledEVITOC,defined'nodata’,withunderlyingshadedreliefDEMat30arcseconds(USGS)

Objec6ve

•  Evaluatetheimpactofchangeinprojec6ononLandSurfaceReflectanceandNDVIProductsover“GoldenTiles”

5ImpactsofProjec6onChangeonLandProducts-NimaPahlevanSSAI/NASAGSFC

Method:SimulateDailyMODIS/VIIRSProducts

MODIS

OLIscene

185km

185km

OLI-derivedsurfacereflectanceproducts

ScanOLIdataaccordingtoVIIRSandMODIS

•  ViewinggeometriesforoneorbitcycleAND•  ThePointSpreadFunc6ons

1kmgridding(GEOVS.SIN)

intercomparison

Swath-levelsimulatedMODISandVIIRSproducts

6ImpactsofProjec6onChangeonLandProducts-NimaPahlevanSSAI/NASAGSFC

Spa6alSamplingUsedinSimula6ons

Agg.3X1 Agg.2X1 Agg.1X1

MoredetailsonthemethodinPahlevan,N,Sarkar,S.,Devadiga,S.,Wolfe,R.E.,Román,M.O.,Vermote,E.,Lin,G.,andXiong,X.(2016).ImpactofSpa6alSamplingonCon6nuityofMODIS-VIIRSLandSurfaceReflectanceProducts:ASimula6onApproach.Submi&edtoIEEETransac4onsofGeoscienceandRemoteSensing(underreview).

8

SampleSimulatedNDVIs(SINVs.GEO)

ImpactsofProjec6onChangeonLandProducts-NimaPahlevanSSAI/NASAGSFC

h30v11 ï d2014016 ï t0502030

0

0.05

0.1

0.15

0.2h31v11 ï d2014016 ï t0502030

0

0.05

0.1

0.15

0.2

Metrics•  Histogram-basedanalysisofdifferencegridsofSINandGEOforLSRandNDVI

–  Per-pixel(i):PercentDifference(PD)andAbsolutePD(APD)

–  Per-area:histogrammean(PD&APD)andRMSD–  Median/min/maxofmeanvalues(mul6pleSIN-GEO)

9ImpactsofProjec6onChangeonLandProducts-NimaPahlevanSSAI/NASAGSFC

−20 −10 0 10 200

50

100

150

200C:NIR

Bias = 0.005%Kurtosis = 3.3PoP @ ±1% = 37.1%

±1%

±5%

±10%

PD (%)

Freq

uenc

y

Australia(barren)

10ImpactsofProjec6onChangeonLandProducts-NimaPahlevanSSAI/NASAGSFC

NWCanada(boreal)

11ImpactsofProjec6onChangeonLandProducts-NimaPahlevanSSAI/NASAGSFC

NorthernChile

12ImpactsofProjec6onChangeonLandProducts-NimaPahlevanSSAI/NASAGSFC

NDVI

13ImpactsofProjec6onChangeonLandProducts-NimaPahlevanSSAI/NASAGSFC

•  Ensembleofsimulateddifferenceimages(variousorbitsandlandcovers)

Conclusion

•  SIN>GEOyield,onaverage,insignificantdifferences(PD<0.5%&difference<1e-3)inLSRandNDVIproducts.

•  RecommendaMon–  Dependingonuserneeds,itispossibletotransiMontogeographicprojecMonwithveryminimalimpactonlandproducts.

–  FurtheranalysesoftheimpactcanbedonebysciencePIs(ifneeded)

14ImpactsofChangeinProjec6ononLandProducts-NimaPahlevanSSAI/NASAGSFC

Backup

ImpactsofSpa6alSamplingonProducts-NimaPahlevanSSAI/NASAGSFC 15

SampleSimulatedSwaths

16

ThesimulatedMODISLSRswathsre-projectedandoverlaidontogriddedMODISLSRs(MYD09)showninRGBfortheSWUSA(left)andNEChina(DOY=247)sites.CourtesyofPeteMa(NASAGSFC/SSAI).

ImpactsofProjec6onChangeonLandProducts-NimaPahlevanSSAI/NASAGSFC

MoredetailsonthemethodinPahlevan,N,Sarkar,S.,Devadiga,S.,Wolfe,R.E.,Román,M.O.,Vermote,E.,Lin,G.,andXiong,X.(2016).ImpactofSpa6alSamplingonCon6nuityofMODIS-VIIRSLandSurfaceReflectanceProducts:ASimula6onApproach.Submi&edtoIEEETransac4onsofGeoscienceandRemoteSensing(underreview).