I have a few questions. - what level of ASTER data are you processing (1A, 1B, or other product)? - what steps did you do to prepare the ASTER VNIR-SWIR bands for FLAASH? - can you calculate the basic statistics of the radiance image you input to FLAASH and the statistics of the FLAASH output file and post them?

Mari, -I have AST_L1T data -First I had layer stacked VNIR and SWIR bands then converted to BIL format since AST_L1T is cross-talked. Then inserted the FLAASH parameters: Atm Model: Tropical water Column mult. 4.11 Aerosol Model: Maritime Aerosol R. none In.Vis.: 40km The rest of the informations are as in header file -Before FLAASH stat Basic Stats Min Max Mean Stdev Band 1 0 255 44.901330 37.097563 Band 2 0 255 27.107641 26.007663 Band 3 0 251 60.868664 46.069570 Band 4 0 166 32.873642 25.351234 Band 5 0 173 17.420035 14.306807 Band 6 0 220 18.141459 15.227885 Band 7 0 204 15.401500 13.301606 Band 8 0 255 13.212713 11.814200 Band 9 0 249 9.779717 8.215574 -After FLAASH Stat Basic Stats Min Max Mean Stdev Band 1 -1299 7455 817.855907 805.724700 Band 2 -31 8958 643.356109 763.798311 Band 3 -962 12681 2803.159186 2145.867290 Band 4 -32749 32729 6576.134001 5198.093173 Band 5 -32753 32757 11269.997102 10115.676820 Band 6 -32764 32759 12192.424962 11204.638870 Band 7 -32746 32763 11287.722531 10515.243759 Band 8 -32727 32766 -8863.864831 11253.730001 Band 9 0 0 0.000000 0.000000 Regards

It looks like there is data in your result but because the range of values is large, the display it not stretching the data so it can be viewed very well. It also look like the output scaled reflectance values are hitting the min/max limit for integers. This usually indicates a problem with the input parameters or calibration of the radiance cube. Did you calibrate the ASTER 1T data first using Radiometric Calibration with 'FLAASH Settings'? What is the scale factor you used in FLAASH for the input data? Can you post your template.txt?

Hi, I think the data have not calibrated using Radiometric calibration with FLAASH setting and that might be the source of this. Do you have a document that directs on how to go about this. Below is the template text ENVI FLAASH PARAMETERS TEMPLATE Project Parameters enviacc.prj.radiance_file = C:\Users\salma\Desktop\disertation\images\BIL\SWIR_ enviacc.prj.reflect_file = C:\Users\salma\Desktop\disertation\images\flaash\SWIR enviacc.prj.filter_func_file = C:\Program Files\Exelis\ENVI52\classic\filt_func\aster.sli enviacc.prj.filter_func_file_index = 0 enviacc.prj.water_band_choice = 1.13 enviacc.prj.red_channel = 0 enviacc.prj.green_channel = 0 enviacc.prj.blue_channel = 0 enviacc.prj.water_abs_channel = 0 enviacc.prj.water_ref_channel = 0 enviacc.prj.kt_upper_channel = 0 enviacc.prj.kt_lower_channel = 0 enviacc.prj.kt_cutoff = 0.0800 enviacc.prj.kt_ratio = 0.5000 enviacc.prj.cirrus_channel = 0 enviacc.prj.water_retrieval = 0 enviacc.prj.user_stem_name = Flaash_ enviacc.prj.modtran_directory = C:\Users\salma\Desktop\disertation\images\flaash\ ; ; MODTRAN Parameters enviacc.modtran.visvalue = 40.0000 enviacc.modtran.f_resolution = 15.0000 enviacc.modtran.day = 4 enviacc.modtran.month = 5 enviacc.modtran.year = 2005 enviacc.modtran.gmt = 7.7300 enviacc.modtran.latitude = -8.9600 enviacc.modtran.longitude = 39.1061 enviacc.modtran.sensor_altitude = 705.0000 enviacc.modtran.ground_elevation = 0.1000 enviacc.modtran.view_zenith_angle = 180.0000 enviacc.modtran.view_azimuth = 0.0000 enviacc.modtran.atmosphere_model = 1 enviacc.modtran.aerosol_model = 4 enviacc.modtran.multiscatter_model = 2 enviacc.modtran.disort_streams = 8 enviacc.modtran.co2mix = 390.0000 enviacc.modtran.water_column_multiplier = 4.1100 ; ; Image Parameters enviacc.img.nspatial = 2776 enviacc.img.nlines = 2449 enviacc.img.data_type = 1 enviacc.img.margin1 = 0 enviacc.img.margin2 = 0 enviacc.img.nskip = 0 enviacc.img.pixel_size = 30.0000 enviacc.img.sensor_name = UNKNOWN-MSI ; ; Analysis Parameters enviacc.ana.aerosol_scaleht = 1.5000 enviacc.ana.use_adjacency = 1 enviacc.ana.output_scale = 10000.0000 enviacc.ana.polishing_res = 0 enviacc.ana.aerosol_retrieval = 0 enviacc.ana.calc_wl_correction = 0 enviacc.ana.reuse_modtran_calcs = 0 enviacc.ana.use_square_slit_function = 0 enviacc.ana.convolution_method = fft enviacc.ana.use_tiling = 1 enviacc.ana.tile_size = 100.0000 ; ; 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 = micron enviacc.spc.lambda = [ 1.6560, 2.1670, 2.2090, 2.2620, 2.3360, 2.4000] enviacc.spc.fwhm = [ -1.000000, -1.000000, -1.000000, -1.000000, -1.000000, -1.000000] enviacc.img.p_input_scale = [ 10.0000, 10.0000, 10.0000, 10.0000, 10.0000, 10.0000] Regards

Mari, I have not calibrated the data using Radiometric Calibration with FLAASH Settings. I have been trying to go through the help menu but stacks somewhere. Is there a document that directs on how to go about that? I used the scale factor of 10 for FLAASH input data. I think here is where the problem might be. The following is the template text: ENVI FLAASH PARAMETERS TEMPLATE ;Written Thu Jul 21 19:54:40 2016 ; ; Project Parameters enviacc.prj.radiance_file = C:\Users\salma\Desktop\disertation\images\BIL\vnir-swir enviacc.prj.reflect_file = C:\Users\salma\Desktop\disertation\images\flaash\vnir-swir- enviacc.prj.filter_func_file = C:\Program Files\ITT\IDL71\products\envi47\filt_func\aster.sli enviacc.prj.filter_func_file_index = 0 enviacc.prj.water_band_choice = 1.13 enviacc.prj.red_channel = 2 enviacc.prj.green_channel = 1 enviacc.prj.blue_channel = 0 enviacc.prj.water_abs_channel = 0 enviacc.prj.water_ref_channel = 0 enviacc.prj.kt_upper_channel = 0 enviacc.prj.kt_lower_channel = 2 enviacc.prj.kt_cutoff = 0.1000 enviacc.prj.kt_ratio = 0.4500 enviacc.prj.cirrus_channel = 0 enviacc.prj.water_retrieval = 0 enviacc.prj.modtran_directory = C:\Users\salma\Desktop\disertation\images\flaash\ ; ; MODTRAN Parameters enviacc.modtran.visvalue = 40.0000 enviacc.modtran.f_resolution = 15.0000 enviacc.modtran.day = 4 enviacc.modtran.month = 5 enviacc.modtran.year = 2005 enviacc.modtran.gmt = 7.7300 enviacc.modtran.latitude = -8.9595 enviacc.modtran.longitude = 39.1054 enviacc.modtran.sensor_altitude = 705.0000 enviacc.modtran.ground_elevation = 0.1000 enviacc.modtran.view_zenith_angle = 180.0000 enviacc.modtran.view_azimuth = 0.0000 enviacc.modtran.atmosphere_model = 1 enviacc.modtran.aerosol_model = 4 enviacc.modtran.multiscatter_model = 2 enviacc.modtran.disort_streams = 8 enviacc.modtran.co2mix = 390.0000 enviacc.modtran.water_column_multiplier = 4.1100 ; ; Image Parameters enviacc.img.nspatial = 5552 enviacc.img.nlines = 4898 enviacc.img.data_type = 1 enviacc.img.margin1 = 0 enviacc.img.margin2 = 0 enviacc.img.nskip = 0 enviacc.img.pixel_size = 15.0000 enviacc.img.sensor_name = ASTER ; ; Analysis Parameters enviacc.ana.aerosol_scaleht = 1.5000 enviacc.ana.use_adjacency = 1 enviacc.ana.output_scale = 10000.0000 enviacc.ana.polishing_res = 0 enviacc.ana.aerosol_retrieval = 0 enviacc.ana.calc_wl_correction = 0 enviacc.ana.reuse_modtran_calcs = 0 enviacc.ana.use_square_slit_function = 0 enviacc.ana.convolution_method = fft enviacc.ana.use_tiling = 1 enviacc.ana.tile_size = 100.0000 ; ; Spectral Parameters enviacc.spc.wavelength_units = micron enviacc.spc.lambda = [ 0.5560, 0.6610, 0.8070, 1.6560, 2.1670, 2.2090, 2.2620, 2.3360, 2.4000] enviacc.spc.fwhm = [ -1.000000, -1.000000, -1.000000, -1.000000, -1.000000, -1.000000, -1.000000, -1.000000, -1.000000] enviacc.img.p_input_scale = [ 10.0000, 10.0000, 10.0000, 10.0000, 10.0000, 10.0000, 10.0000, 10.0000, 10.0000] Regards

Yes, I would first use Radiometric calibration with the original VNIR and SWIR datasets. Use the 'FLAASH Settings' option. This should apply the scale factors to convert the data to the expected units for FLAASH (microW/(cm*2/sr/nm). Then use Layer Stacking to stack the VNIR+SWIR bands into one file and convert the layer stacked file to BIL using Convert Interleave. When you select this stacked dataset for FLAASH, you can use a scale factor of 1. This should process the data in the correct units.

Mari, Thanks very much for the assistance. I have one more concern. When trying to do Radiometric Calibration it requires me to apply gain and offset. I have read that you can find those values for each band in the header file but they are a bit confusing me. From the below some of the header file which are gain and offset value? Or otherwise please let me know how to obtain the values. END_GROUP = PROCESSINGPARAMETERS1 GROUP = UNITCONVERSIONCOEFF1 OBJECT = INCL1 NUM_VAL = 1 VALUE = 0.675999999046326 END_OBJECT = INCL1 OBJECT = 2:12 PM 7/25/20161 NUM_VAL = 1 VALUE = -0.675999999046326 END_OBJECT = OFFSET1 OBJECT = CONUNIT1 NUM_VAL = 1 VALUE = "W/m2/sr/um" END_OBJECT = CONUNIT1 END_GROUP = UNITCONVERSIONCOEFF1 END_GROUP = VNIRBAND1DATA Regards

Those values are part of the unit conversion coefficients according to the ASTER User's Handbook: https://asterweb.jpl.nasa.gov/content... ENVI should extract these automatically and they should show up under the Metadata Viewer ->Spectral tab. If you run the Radiometric Calibration tool with ASTER 1T using 'FLAASH Settings' you should get a file with the factors applied and in the units expected by FLAASH.

Mari, Thanks very much for your help. I tried to follow your instruction and now it seems to be fine except that when I apply water column multiplier for the tropical region (>4.11 which is standard) where my ASTER data are originated I get very low reflectance values for mostly band 8 and 9 in such that no information is displayed. Is it ok to use the value below that (let say 1 for US standard) which I get values which they seems to be reasonable to me. Regards

Yes, I think it is fine to reduce the water column as these are only guidelines. The multiplier gives you the ability to increase or decrease the water column along with the generalized atmospheric model.

Thank you very much Mari. Highly appriciated.