Hi ENVI user community, I hope somebody can help me identify what I’m doing wrong with FLAASH. I’m using 4.4 (so that’s probably the start of the problem right ) I’ve been following the steps outlined in the tutorial http://www.ittvis.com/por...SH_Multispectral.pdf The results seem especially strange in bands 5 & 7, making me think that the entire operation is suspect. Below I’ve outlined what is going on, and the procedure I’ve taken to do it. This is the first time that I’ve used ENVI for any processing – so I’m hoping it’s a simple, blindingly obvious mistake on my part. Problems Output appears “wrong” Bands 5 and 7 have ranges from -32768 to +32767 Large number of negative values in both bands It’s as if the result has been too large, reached a cutoff point and started writing again from the negative side of the graph. http://www.flickr.com/pho...8855@N04/4991487425/ http://www.flickr.com/pho...8855@N04/4991487363/ (sorry about the links to flickr - I couldnt get the images to upload to the post - file names are descriptive of the image) This gives for example, a very strange 2D plot of the data in feature space http://www.flickr.com/pho...8855@N04/4992108518/ http://www.flickr.com/pho...8855@N04/4992108598/ Spectral profiles do not appear as I would expect them to. Highly reflecting sites (eg saltpans) giving very low values in band 5 http://www.flickr.com/pho...8855@N04/4991541899/ http://www.flickr.com/pho...8855@N04/4992148652/ The processing steps I took Convert Geotiff DN to radiance http://www.flickr.com/pho...8855@N04/4991518749/ http://www.flickr.com/pho...8855@N04/4992125622/ Band math, divide by 10 to give radiance in [μW/(cm2*sr*nm)]. Stack individual layers http://www.flickr.com/pho...8855@N04/4991562099/ - possible hint to problem here - the histograms look very "spiky" - is that normal? compared to the histograms of the geotiffs, which are very smooth. having said that it is only bands 5 & 7 that appear to be radically wrong. band 5 =yellow band6 = light blue Manually input wavelength into header file http://www.flickr.com/pho...8855@N04/4991551259/ Run flaash with following template file. ; ;ENVI FLAASH PARAMETERS TEMPLATE (4.4) ;Written Mon Sep 13 15:29:56 2010 ; ; Project Parameters enviacc.prj.radiance_file = C:\steve\ENVI_test\20031113\covert_to_radiance\9480_20031113_div10_allstack_bil enviacc.prj.reflect_file = C:\steve\ENVI_test\20031113\flaash\9480_20031113_flaash enviacc.prj.filter_func_file = C:\Program Files\ITT\IDL64\products\envi44\filt_func\tm.sli enviacc.prj.filter_func_file_index = 6 enviacc.prj.water_band_choice = 1.13 enviacc.prj.red_channel = 3 enviacc.prj.green_channel = 2 enviacc.prj.blue_channel = 0 enviacc.prj.water_abs_channel = 0 enviacc.prj.water_ref_channel = 0 enviacc.prj.kt_upper_channel = 6 enviacc.prj.kt_lower_channel = 3 enviacc.prj.kt_cutoff = 0.1000 enviacc.prj.kt_ratio = 0.4500 enviacc.prj.cirrus_channel = 0 enviacc.prj.water_retrieval = 0 enviacc.prj.user_stem_name = 9480_20031113_flaash_working_ enviacc.prj.modtran_directory = C:\steve\ENVI_test\20031113\flaash\ ; ; MODTRAN Parameters enviacc.modtran.visvalue = 80.0000 enviacc.modtran.f_resolution = 15.0000 enviacc.modtran.day = 13 enviacc.modtran.month = 11 enviacc.modtran.year = 2003 enviacc.modtran.gmt = 23.8611 enviacc.modtran.latitude = -28.8708 enviacc.modtran.longitude = 145.1514 enviacc.modtran.sensor_altitude = 705.0000 enviacc.modtran.ground_elevation = 0.1530 enviacc.modtran.view_zenith_angle = 180.0000 enviacc.modtran.view_azimuth = 0.0000 enviacc.modtran.atmosphere_model = 2 enviacc.modtran.aerosol_model = 1 enviacc.modtran.multiscatter_model = 2 enviacc.modtran.disort_streams = 8 enviacc.modtran.co2mix = 390.0000 enviacc.modtran.water_column_multiplier = 1.0000 ; ; Image Parameters enviacc.img.nspatial = 8171 enviacc.img.nlines = 7011 enviacc.img.data_type = 4 enviacc.img.margin1 = 0 enviacc.img.margin2 = 0 enviacc.img.nskip = 0 enviacc.img.pixel_size = 30.0000 enviacc.img.sensor_name = Landsat TM5 ; ; Analysis Parameters enviacc.ana.aerosol_scaleht = 2.0000 enviacc.ana.use_adjacency = 1 enviacc.ana.output_scale = 10000.0000 enviacc.ana.polishing_res = 0 enviacc.ana.aerosol_retrieval = 1 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 = [ 0.4850, 0.5600, 0.6600, 0.8300, 1.6500, 2.2150] enviacc.spc.fwhm = [ -1.000000, -1.000000, -1.000000, -1.000000, -1.000000, -1.000000] enviacc.img.p_input_scale = [ 1.0000, 1.0000, 1.0000, 1.0000, 1.0000, 1.0000] Thanks Steve