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Last Post 14 Oct 2012 08:57 PM by  anon
FLAASH under 500 nm
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anon



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14 Oct 2012 08:57 PM
    Hello, I'm trying to use FLAASH to correct hyper-spectral images taken by CASI-1500, but the results aren´t good compared with In situ. The In situ data are collected during the fly time. The FLAASH results have an obvious curving down. Meanwhile, In situ data have a slight curving down. I have changed different even it is unreasonable for my area, it seems change the intensity of reflectance. This is the result between 4 hyper-spectral images and In situ one the same position. http://www.flickr.com/pho...94104/in/photostream This is my template. ; ; MODTRAN Parameters enviacc.modtran.visvalue = 16.0000 enviacc.modtran.f_resolution = 5.0000 enviacc.modtran.day = 13 enviacc.modtran.month = 8 enviacc.modtran.year = 2012 enviacc.modtran.gmt = 0.8353 enviacc.modtran.latitude = 23.3021 enviacc.modtran.longitude = 120.6691 enviacc.modtran.sensor_altitude = 2.2770 enviacc.modtran.ground_elevation = 0.5000 enviacc.modtran.view_zenith_angle = 180.0000 enviacc.modtran.view_azimuth = 0.0000 enviacc.modtran.atmosphere_model = 2 enviacc.modtran.aerosol_model = 0 enviacc.modtran.multiscatter_model = 2 enviacc.modtran.disort_streams = 16 enviacc.modtran.co2mix = 410.0000 enviacc.modtran.water_column_multiplier = 1.0000 ; ; Image Parameters enviacc.img.nspatial = 2215 enviacc.img.nlines = 12542 enviacc.img.data_type = 12 enviacc.img.margin1 = 0 enviacc.img.margin2 = 0 enviacc.img.nskip = 0 enviacc.img.pixel_size = 1.0000 enviacc.img.sensor_name = CASI ; ; Analysis Parameters enviacc.ana.aerosol_scaleht = 2.0000 enviacc.ana.use_adjacency = 1 enviacc.ana.output_scale = 10000.0000 enviacc.ana.polishing_res = 9 enviacc.ana.aerosol_retrieval = 0 enviacc.ana.calc_wl_correction = 0 enviacc.ana.reuse_modtran_calcs = 0 enviacc.ana.use_square_slit_function = 1 enviacc.ana.convolution_method = fft enviacc.ana.use_tiling = 0 enviacc.ana.tile_size = 1000.0000 ; ; GParameters Parameters enviacc.gparameters.gfact = 0 enviacc.gparameters.gval = 0.0000 enviacc.gparameters.use_lr_method = 0 enviacc.gparameters.multikernel = 1 enviacc.gparameters.autoroi = auto enviacc.gparameters.selarg = a ; ; Spectral Parameters enviacc.spc.wavelength_units = nanometer enviacc.spc.lambda = [ 367.6000, 377.2000, 386.8000, 396.5000, 406.1000, 415.7000, 425.3000, 434.9000, 444.5000, 454.1000, 463.7000, 473.3000, 482.9000, 492.4000, 502.0000, 511.6000, 521.2000, 530.7000, 540.3000, 549.9000, 559.4000, 569.0000, 578.5000, 588.1000, 597.6000, 607.2000, 616.7000, 626.2000, 635.8000, 645.3000, 654.9000, 664.4000, 673.9000, 683.5000, 693.0000, 702.5000, 712.1000, 721.6000, 731.1000, 740.7000, 750.2000, 759.7000, 769.3000, 778.8000, 788.3000, 797.9000, 807.4000, 816.9000, 826.5000, 836.0000, 845.5000, 855.1000, 864.6000, 874.2000, 883.7000, 893.3000, 902.8000, 912.4000, 921.9000, 931.5000, 941.1000, 950.6000, 960.2000, 969.8000, 979.4000, 988.9000, 998.5000, 1008.1000, 1017.7000, 1027.3000, 1036.9000, 1046.5000] enviacc.spc.fwhm = [ 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000, 9.600000] enviacc.img.p_input_scale = [ 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000, 1000.0000] Thank for helps.

    MariM



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    22 Oct 2012 08:19 AM
    It looks like there is a slight over-correction in the blue bands, which isn't uncommon. Since you cannot perform an aerosol retrieval, you can try setting the initial visibility to a higher value such as 80-100km to try and compensate.

    Deleted User



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    22 Oct 2012 07:35 PM
    Hi~ It seems a little help for over-correction. Taiwan are a Monsoon climate. It also be a factor that cause slight over-correction. The origin MODTRAN Report has User-defined model. Is it possible to add a customer model in FLAASH? Thank you~
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