Hi, ENVI provide special tool for radiometric calibration WV images but unfortunately in older versions ENVI this tool does not complain if the input is WV-2. In ENVI 4.8, this bug has been fixed. For radiometric calibrationWV-2 images in older versions ENVI you can use Aplly Gain and Offset (with gains calculated from metadata). You can found data for radiometric calibration in *.IMD file. For examples: compressionType = "None"; BEGIN_GROUP = BAND_C ...... absCalFactor = 9.295654e-03; effectiveBandwidth = 4.730000e-02; TDILevel = 24; END_GROUP = BAND_C BEGIN_GROUP = BAND_B You can calculate the value of gain for each band with a calculator or Excel. gain= absCalFactor/effectiveBandwidth and than use it with Apply Gain and Offset tool (Basic Tools -> Preprocessing -> General Purpose Utilities) Gain - calculated values, Offset - 0. Type - float point.Your result - radiance image, values in units of W*m-2 * µm-1* sr-1. Scale factor (FLAASH window) will be equal 10 for all bands (use single scale factor for all bands). Best Regards...

I just imported a WV-2 multispectral dataset into ENVI 5.2, using File > Open As > WorldView-2 and choosing the *.TIL file. I then performed Radiometric Calibration on it, converting it to Radiance in BIL interleave with floating point values. ENVI automatically extracted the gain and offset values from the IMD file (this was not true in versions of ENVI before 5.2). The output from this looked great. I wonder if perhaps you've done something different than what I describe above? If so, providing those details about what is different might help us track down what is going wrong for you.

Hi Alex, I calculated the gains from the absCalFactor and effectiveBandwidth and used them in the Apply Gain and Offset tool. When I try to use the radiance image in FLAASH it requires the BIL or BIP file type. If I try to use the radiance image in the Radiometric Calibration tool it says "Calibration requires gain and offset for each band". I'm not sure why it is not recognizing the applied gains/offsets from the previous step. Do you know what might be causing this issue? The file header looks like this for the radiance image: ENVI description = { Gain and Offset Correction [Fri Feb 20 09:51:02 2015]} samples = 1760 lines = 1894 bands = 8 header offset = 0 file type = ENVI Standard data type = 4 interleave = bsq sensor type = Unknown byte order = 0 x start = 4243 y start = 6004 map info = {UTM, 1.000, 1.000, 297668.000, 2153320.000, 2.0000000000e+000, 2.0000000000e+000, 5, North, WGS-84, units=Meters} coordinate system string = {PROJCS["UTM_Zone_5N",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",500000.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",-153.0],PARAMETER["Scale_Factor",0.9996],PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]]} wavelength units = Unknown band names = { Gainoff (Band 1:15JAN29210848-M2AS-053883497010_01_P001.TIF), Gainoff (Band 2:15JAN29210848-M2AS-053883497010_01_P001.TIF), Gainoff (Band 3:15JAN29210848-M2AS-053883497010_01_P001.TIF), Gainoff (Band 4:15JAN29210848-M2AS-053883497010_01_P001.TIF), Gainoff (Band 5:15JAN29210848-M2AS-053883497010_01_P001.TIF), Gainoff (Band 6:15JAN29210848-M2AS-053883497010_01_P001.TIF), Gainoff (Band 7:15JAN29210848-M2AS-053883497010_01_P001.TIF), Gainoff (Band 8:15JAN29210848-M2AS-053883497010_01_P001.TIF)}

Hello Peg, I've tried the following steps using ENVI 5.2: 1) File>Open As>WorldView-2> .TIL File 2) Radiometric Calibration Tool> Error pops up "Calibration requires gain and offset for each band". 3) Apply Gains and Offset Tool (after calculating values manually from .IMD file since ENVI does not populate these values automatically for me)> Output Data Type= Float 4) Using the corrected gains and offset file> Radiometric Calibration> "Same error as above", I'm not sure if the Gains and Offset tool is working- when viewing the metadata of the outputed file (from the Gains and Offset tool) in the Spectral category, it only shows values for the Wavelengths and FWHM, but no values are listed in the Radiance Gains or Radiance Offsets columns of the metadata.

Interesting. I wonder why it is working for me, and not for you? Is this a multispectral WV-2 dataset? Are you sure you are working in ENVI 5.2 when this happens? This is behavior that I would have expected in an earlier version, but not in ENVI 5.2. Peg Exelis VIS

When you open the original WV-2 using the TIL, go to the Metadata viewer and then the Spectral Tab. Here is where the gains/offsets should be located if they are successfully extracted from the metadata on import. Can you save the text from the metadata viewer and post it? Is your dataset in NITF format? There was an issue with extraction of the gains/offsets from the IMD for WV datasets in NITF format in ENVI 5.1 that was resolved in ENVI 5.2. You would not want to use the Apply gain/offsets tool in this case. This is applying the values to the dataset, not updating the metadata.

Here is the full metadata exported to text: It's not reading any gains/offsets from the file. What tool for adding gain/offsets would be a better choice for this? Thanks ---- Raster Properties ---- Dataset = E:\Albizia\DigitalGlobe_PostIselle\053883497020_01\053883497020_01_P001_MUL\15JAN10211021-M2AS-053883497020_01_P001.TIF Size = 159,054,812 bytes Type = TIFF Columns = 3270 Rows = 6010 Bands = 8 Interleave = BSQ Data Type = Byte Sensor Type = WorldView-2 Product Type = Standard2A ---- Map Info Properties ---- Type = Projected Pixel Tie Point X = 0.0 Pixel Tie Point Y = 0.0 Map Tie Point X = 295840.0 Map Tie Point Y = 2171440.0 Pixel Size X = 2.0 Pixel Size Y = 2.0 Units = Meters Rotation = 0.0 ---- Associated RPC Info Properties ---- Line Offset = 3004.0 Sample Offset = 1634.0 Latitude Offset = 19.5736 Longitude Offset = -154.9151 Height Offset = 102.0 Line Scale = 3005.0 Sample Scale = 1635.0 Latitude Scale = 0.0547 Longitude Scale = 0.0318 Height Scale = 501.0 Line Numerator 1 = 1.48258400E-003 Line Numerator 2 = 6.21945800E-003 Line Numerator 3 = -1.00756200E+000 Line Numerator 4 = 0.00000000E+000 Line Numerator 5 = 1.39762100E-005 Line Numerator 6 = 0.00000000E+000 Line Numerator 7 = 0.00000000E+000 Line Numerator 8 = -5.16885700E-005 Line Numerator 9 = -7.48177400E-004 Line Numerator 10 = 0.00000000E+000 Line Numerator 11 = 0.00000000E+000 Line Numerator 12 = 0.00000000E+000 Line Numerator 13 = 1.08245800E-008 Line Numerator 14 = 0.00000000E+000 Line Numerator 15 = -1.21662100E-007 Line Numerator 16 = -5.68573900E-007 Line Numerator 17 = 0.00000000E+000 Line Numerator 18 = 0.00000000E+000 Line Numerator 19 = 0.00000000E+000 Line Numerator 20 = 0.00000000E+000 Line Denominator 1 = 1.00000000E+000 Line Denominator 2 = 5.18252500E-006 Line Denominator 3 = 7.39872600E-004 Line Denominator 4 = 0.00000000E+000 Line Denominator 5 = 0.00000000E+000 Line Denominator 6 = 0.00000000E+000 Line Denominator 7 = 0.00000000E+000 Line Denominator 8 = -3.76049600E-008 Line Denominator 9 = 5.60208000E-007 Line Denominator 10 = 0.00000000E+000 Line Denominator 11 = 0.00000000E+000 Line Denominator 12 = 0.00000000E+000 Line Denominator 13 = 0.00000000E+000 Line Denominator 14 = 0.00000000E+000 Line Denominator 15 = 0.00000000E+000 Line Denominator 16 = 0.00000000E+000 Line Denominator 17 = 0.00000000E+000 Line Denominator 18 = 0.00000000E+000 Line Denominator 19 = 0.00000000E+000 Line Denominator 20 = 0.00000000E+000 Sample Numerator 1 = -4.79922200E-004 Sample Numerator 2 = 1.02041800E+000 Sample Numerator 3 = 2.07442600E-002 Sample Numerator 4 = 0.00000000E+000 Sample Numerator 5 = -1.61880700E-004 Sample Numerator 6 = 0.00000000E+000 Sample Numerator 7 = 0.00000000E+000 Sample Numerator 8 = 2.42868600E-004 Sample Numerator 9 = 3.15246000E-005 Sample Numerator 10 = 0.00000000E+000 Sample Numerator 11 = 0.00000000E+000 Sample Numerator 12 = 2.59273300E-008 Sample Numerator 13 = -2.67559500E-007 Sample Numerator 14 = -4.41037000E-008 Sample Numerator 15 = -7.08450200E-008 Sample Numerator 16 = 0.00000000E+000 Sample Numerator 17 = 0.00000000E+000 Sample Numerator 18 = 0.00000000E+000 Sample Numerator 19 = 0.00000000E+000 Sample Numerator 20 = 0.00000000E+000 Sample Denominator 1 = 1.00000000E+000 Sample Denominator 2 = 2.45251400E-004 Sample Denominator 3 = 1.74487500E-004 Sample Denominator 4 = 0.00000000E+000 Sample Denominator 5 = 0.00000000E+000 Sample Denominator 6 = 0.00000000E+000 Sample Denominator 7 = 0.00000000E+000 Sample Denominator 8 = -1.36633000E-008 Sample Denominator 9 = 2.44655000E-007 Sample Denominator 10 = -4.32212200E-008 Sample Denominator 11 = 0.00000000E+000 Sample Denominator 12 = 0.00000000E+000 Sample Denominator 13 = 0.00000000E+000 Sample Denominator 14 = 0.00000000E+000 Sample Denominator 15 = 0.00000000E+000 Sample Denominator 16 = 0.00000000E+000 Sample Denominator 17 = 0.00000000E+000 Sample Denominator 18 = 0.00000000E+000 Sample Denominator 19 = 0.00000000E+000 Sample Denominator 20 = 0.00000000E+000 Tile Offset X = 0.0 Tile Offset Y = 0.0 Geoid Offset = 0.0 ---- Coordinate System Properties ---- Projcs = "WGS_1984_UTM_Zone_5N" Geogcs = "GCS_WGS_1984" Datum = "D_WGS_1984" Spheroid = "WGS_1984",6378137.0,298.257223563 Prime Meridian = "Greenwich",0.0 Unit = "Degree",0.0174532925199433 Projection = "Transverse_Mercator" False Easting = 500000.0 False Northing = 0.0 Central Meridian = -153.0 Scale Factor = 0.9996 Latitude of Origin = 0.0 Unit = "Meter",1.0 Coordinate System String = PROJCS["WGS_1984_UTM_Zone_5N",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",500000.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",-153.0],PARAMETER["Scale_Factor",0.9996],PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]] ---- Extents Properties ---- Extent Left = 295840.0 Extent Top = 2171440.0 Extent Right = 302380.0 Extent Bottom = 2159420.0 Units = Meters ---- Spectral Properties ---- Band Names 1 = CoastalBlue Band Names 2 = Blue Band Names 3 = Green Band Names 4 = Yellow Band Names 5 = Red Band Names 6 = RedEdge Band Names 7 = NIR1 Band Names 8 = NIR2 Wavelengths 1 = 427.3 Wavelengths 2 = 477.9 Wavelengths 3 = 546.2 Wavelengths 4 = 607.8 Wavelengths 5 = 658.8 Wavelengths 6 = 723.7 Wavelengths 7 = 832.5 Wavelengths 8 = 908.0 FWHM 1 = 51.8 FWHM 2 = 60.8 FWHM 3 = 69.8 FWHM 4 = 38.5 FWHM 5 = 59.3 FWHM 6 = 39.8 FWHM 7 = 117.8 FWHM 8 = 92.5 Irradiance 1 = 1758.2229 Irradiance 2 = 1974.2416 Irradiance 3 = 1856.4104 Irradiance 4 = 1738.4791 Irradiance 5 = 1559.4555 Irradiance 6 = 1342.0695 Irradiance 7 = 1069.7302 Irradiance 8 = 861.2866 ---- Image Parameters Properties ---- Cloud Cover = 0.000000% Sun Azimuth = 154.600000° Sun Elevation = 44.600000° ---- Time Properties ---- Acquisition Time = 2015-01-10T21:10:21.743975Z

It is strange that it is getting all of the metadata but the gains/offsets. If you save the dataset to ENVI format, you might try using Edit ENVI Header and entering the gains/offsets in the header and see if the calibration tool recognizes the information. Have you tried this in ENVI 5.2? You mentioned you were using ENVI 5.1 initially.

If the .IMD file contains the key absCalFactor foreach band, it should be picking up the gains. I am curious as to what the .IMD file for the image looks like. I am curious if the file being opened is a .TIF with a .HDR in the same directory. Ryan Exelis Vis

hi,
I know this this a bit older thread, But interestingly I am having the same gain and offset missing problem for WV 3 images using ENVI 5.4.1. I am receiving the same error message! Just wondering whether you found a way to get the radiometric correction done at the end? I am having really a hard time with my image..

Thank you!