Initial Radiometric Calibration of the AWiFS using Vicarious Calibration Techniques PDF
Preview Initial Radiometric Calibration of the AWiFS using Vicarious Calibration Techniques
RR EE LL EE AA SS EE DD - - P P rr inin Stennis Space Center tt ee dd d d oo cc uu mm ee nn tt ss m m Initial Radiometric Calibration of the AWiFS using aa yy b b ee o o Vicarious Calibration Techniques bb ss oo lele tt ee ;; v v aa lidlid aa tt ee p p Mary Pagnutti rr ioio rr t t oo u u ss ee .. Science Systems and Applications, Inc. John C. Stennis Space Center, MS 39529 228-688-2135 [email protected] JACIE Civil Commercial Imagery Evaluation Workshop Laurel, Maryland, USA March 14–16, 2006 RR EE LL EE AA SS EE DD - - Selected Targets – Wiggins, MS P P rr inin Stennis Space Center tt ee dd d d oo Gravel Pit Sand Rye Grass Field cc Four selected targets of opportunity near near Perkinston, MS near Big Level, MS uu mm ee Stennis Space Center are hundreds of nn tt ss m m meters across: aa yy b b – Two gravel pit sand sites ee o o bb – Large monoculture fields ss oo Specific lele – Cut grass amateur golf course tt ee Target ;; v v aa Areas lidlid aa Highlighted tt ee p p rr ioio rr 0 100 200 Meters 0 200 400 Meters t t Includes material © oo u u Gravel Pit Sand Grass Field Space Imaging, LLC ss ee near Wiggins, MS near Big Level, MS .. AWiFS imagery (4,3,2) 0 100 200 Meters 0 50 100 Meters April 27, 2005 Includes material ©DigitalGlobe, Inc. March 16, 2006 JACIE Civil Commercial Imagery Evaluation Workshop, Laurel, MD 2 RR EE LL EE AA SS EE DD - - Selected Targets - Park Falls, WI P P rr inin Stennis Space Center tt ee dd d d oo cc uu mm A target of opportunity was found near an ee nn tsts Aerosol Robotic Network (AERONET) site m m aa near Park Falls yy b b ee – Large grass field o o bb ss oo lele tt ee ;; v v aa lidlid aa tt ee p p rr ioio rr t t oo u u ss ee .. Landsat 7 imagery (7,4,2) August 5, 2005 Target field 150 m x 400 m AWiFS imagery (4,3,2) August 5, 2005 March 16, 2006 JACIE Civil Commercial Imagery Evaluation Workshop, Laurel, MD 3 RR EE LL EE AA SS EE DD - - Ground Reflectance Measurements P P rr inin Stennis Space Center tt ee dd d d oo cc uu mm • ASD FieldSpec® FR spectroradiometer ee nn tt measurements of Spectralon® panels ss m m and several target areas were taken aa yy b b – ~50 m x 50 m area of a grassy ee o o bb field/golf course ss oo lele – ~100 m x 200 m area of a rye tt ee ; v; v grass field aa lidlid – ~100 m x 100 m area of two sand aa tt ee sites p p rr ioio • Measurements were taken along rr t t oo transects aligned with the sensor u u ss ee azimuth .. – Measurements were taken at nadir and satellite elevation angles to account for BRDF effects – All measurements were taken while walking to increase spatial averaging – Periodic Spectralon panel measurements were taken • All data were acquired within 40 minutes of satellite overpass March 16, 2006 JACIE Civil Commercial Imagery Evaluation Workshop, Laurel, MD 4 RR EE LL EE AA SS EE DD - - SSC Calibration and Characterization P P rr inin Stennis Space Center tt ee of ASD FieldSpec Spectroradiometers dd d d oo cc uu mm ee • NASA SSC maintains four ASD nn tt ss m m FieldSpec FR spectroradiometers aa yy b b – Laboratory transfer radiometers ee o o bb ss – Ground surface reflectance for V&V oo lele tt field collection activities ee ;; v v aa lidlid • Radiometric Calibration aa tt e pe p – NIST-calibrated integrating sphere rr ioio rr serves as source with known t t oo u u spectral radiance ss ee .. • Spectral Calibration – Laser and pen lamp illumination of integrating sphere • Environmental Testing – Temperature stability tests performed in environmental chamber March 16, 2006 JACIE Civil Commercial Imagery Evaluation Workshop, Laurel, MD 5 RR EE LL EE AA SS EE DD - - Novel Hyperspectral Sun Photometer P P rr inin Stennis Space Center tt ee dd d d SSC 1/10/04 -16:33 GMT oo cc uu • Novel hyperspectral sun photometer is capable Percent mm ASR 27 ASD Difference Difference ee nn of acquiring measurements comparable to both tsts Band Generated Generated ASR-ASD 1 -(asd/asr) m m ASRs and MFRSRs by making use of the aa 380 nm 0.588 0.5982 -0.010 -1.74% yy b b laboratory radiometric calibration of the 400 nm 0.495 0.4852 0.010 1.99% ee o o bb FieldSpec FR spectroradiometers 440 nm 0.366 0.3216 0.044 12.14% ss oo lele – Optical Depth/Transmission 520 nm 0.224 0.1988 0.025 11.25% tt ee ; v; v – Diffuse-to-Global Ratio 610 nm 0.161 0.1563 0.005 2.91% aa lidlid 670 nm 0.108 0.1002 0.008 7.26% aa • Sun photometer developed with fewer tete 780 nm 0.07 0.0691 0.001 1.33% p p limitations than current sun photometers, riorio 870 nm 0.049 0.0508 -0.002 -3.58% r tor to utilizing equipment already used in the field RMS 1:8 0.019 u u ss – Radiometrically calibrated FieldSpec FR Sample Results ee .. spectroradiometers – 99% reflectance Spectralon panels • Measurements are made only at the time of overpass, thus reducing the impact of a changing atmosphere on the calculation of optical depth Novel Hyperspectral Sun Photometer Setup March 16, 2006 JACIE Civil Commercial Imagery Evaluation Workshop, Laurel, MD 6 RR EE LL EE AA SS EE DD - - Comparison to Spectralon Panel P P rr inin Stennis Space Center tt ee dd d d oo cc uu • Verification of parameters used to generate MODTRAN at-sensor radiance estimate mm ee nn – Measuring the radiance of Spectralon panel with a well-calibrated tt ss m m spectroradiometer is a way of measuring atmospheric global and diffuse aa yy irradiance b b e oe o – Use ground truth data and geometry modeling an ASD FieldSpec FR bb ss spectroradiometer measuring a 99% reflectance Spectralon panel as input to oo lele MODTRAN to predict radiance tt ee ;; v v – Compare MODTRAN-calculated radiance to actual radiance measured from aa lidlid Spectralon panel to verify the atmospheric model aa tt ee p p rr ioio rr t t oo u u ss Spectralon Radiance ee .. Avg. Spectralon Radiance MODTRAN Radiance March 16, 2006 JACIE Civil Commercial Imagery Evaluation Workshop, Laurel, MD 7 RR EE LL EE AA SS EE DD - - Data Acquisitions – Wiggins, MS P P rr inin Stennis Space Center tt ee dd d d oo cc uu mm ee nn tsts Overpass Satellite Satellite Sun Sun m m aa Date Camera Time (UTC) Elevation Azimuth Elevation Azimuth yy b b ee o o bb ss Mar 24, 2005 B 16:59 71.1 deg 285 deg 57.2 deg 149.8 deg oo lele tt ee ;; v v aa lidlid Apr 27, 2005 B 16:50 84.5 deg 285 deg 67.7 deg 135.4 deg aa tt ee p p rr ioio r tr t 0 0 o uo u 330 30 330 30 ss ee .. 300 60 300 60 Sun Sun 15 AWiFS 15 AWiFS 30 30 45 45 60 60 270 90 75 90 270 90 75 90 N 240 120 240 120 210 150 210 150 180 180 Wiggins, MS, 3/24/05 Wiggins, MS, 4/27/05 March 16, 2006 JACIE Civil Commercial Imagery Evaluation Workshop, Laurel, MD 8 RR EE LL EE AA SS EE DD - - Data Acquisitions – Park Falls, WI P P rr inin Stennis Space Center tt ee dd d d oo cc uu mm ee nn tsts Overpass Satellite Satellite Sun Sun m m aa Date Camera Time (UTC) Elevation Azimuth Elevation Azimuth yy b b ee o o bb ss Aug 5, 2005 A 17:02 83.9 deg 103 deg 57.8 deg 149.7 deg oo lele tt ee ;; v v aa lidlid aa tt ee p p rr ioio r tr t 0 oo u u 330 30 ss ee .. 300 60 Sun 15 AWiFS 30 45 60 75 270 90 90 N 240 120 210 150 180 Park Falls, WI, 8/5/05 March 16, 2006 JACIE Civil Commercial Imagery Evaluation Workshop, Laurel, MD 9 RR EE LL EE AA SS EE DD - - Green Band Calibration Summary P P rr inin Stennis Space Center tt ee dd d d oo cc uu mm ee nn tt ss m m aa yy b b ee o o bb ss oo lele tt ee ;; v v aa lidlid aa tt ee p p rr ioio rr t t oo u u ss ee .. March 16, 2006 JACIE Civil Commercial Imagery Evaluation Workshop, Laurel, MD 10
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