Calibration Utilities
Use Calibration Utilities to apply calibration factors to AVHRR, MSS, QuickBird, TM, TIMS, and WorldView-1 data, and to use a variety of atmospheric correction techniques.
AVHRR Calibration
Use the AVHRR calibration utility to calibrate AVHRR data from the NOAA-12, -14, -15, -16, -17, and -18 satellites. Bands 1 and 2 are calibrated to percent reflectance and bands 3, 4, and 5 are calibrated to brightness temperature, in degrees Kelvin. For details, see Calibrating AVHRR Data.
Landsat MSS Calibration
Use Landsat MSS calibration to convert Landsat MSS digital numbers to radiance or exoatmospheric reflectance (reflectance above the atmosphere) using published post-launch gains and offsets (see Landsat TM Calibration for more details):
From the ENVI main menu bar, select Basic Tools Preprocessing Calibration Utilities Landsat MSS. The Input File dialog appears.
Select an input file and perform optional Spatial Subsetting and/or Spectral Subsetting, then click OK. The MSS Calibration Parameters dialog appears.

From the Satellite drop-down list, select the satellite type.

Enter the data acquisition month, day, year, and sun angle into the appropriate fields.

Select the output type by selecting from the Radiance or Reflectance radio buttons.

Select output to File or Memory.

Click OK.
Landsat TM Calibration
Use Landsat TM calibration to convert Landsat TM or ETM digital numbers to radiance or exoatmospheric reflectance (reflectance above the atmosphere) using published post-launch gains and offsets (see http://landsat.usgs.gov/technical_de...bration_files/ and http://edcftp.cr.usgs.gov/pub/metada...e/landsat_etm/).
The spectral radiance (Ll) is calculated using the following equation:
where QCAL is the calibrated and quantized scaled radiance in units of digital numbers, LMINl is the spectral radiance at QCAL = 0, LMAXl is the spectral radiance at QCAL = QCALMAX, and QCALMAX is the range of the rescaled radiance in digital numbers. LMINl and LMAXl are derived from tables provided in the Landsat Technical Notes (August 1986) with the information provided through the TM Calibration Parameters dialog in ENVI. QCALMAX is 255 for all TM data and 127 for all MSS data except Band 4 (0.8 to 1.1 mm), which is 63 for certain time periods (data acquired before February 1, 1979 for Landsat 1-3 and processed before October 22, 1982). The resulting radiance (Ll) is in units of watts per square meter per steradian per micrometer (W/(m2*sr*mm)).
The exoatmospheric reflectance (rp) is calculated using the following equation:
where Ll is the spectral radiance, d is the Earth-Sun distance in astronomical units, ESUNl is the mean solar exoatmospheric irradiance, and qs is the solar zenith angle in degrees. ESUNl is derived from tables provided in the Landsat Technical Notes (August 1986). The resulting reflectance is unitless. See http://landsat.usgs.gov/dcidocuments/L5TMCal2003.pdf for further details.
TM band 6, if present, is converted to temperature. If 7 bands are input, the 6th band is assumed to be the thermal infrared band. If only 6 bands are input, then it is assumed that there is no thermal infrared band.
For Landsat 7 GeoTIFF files that do not contain calibration coefficients, you can use Landsat TM calibration to specify the calibration coefficients and other related parameters, or you can extract the parameters from a Web server.
Select one of the following options from the ENVI main menu bar:
Basic Tools Preprocessing Calibration Utilities Landsat TM
Basic Tools Preprocessing Data-Specific Utilities Landsat TM Landsat TM Calibration
Spectral Preprocessing Calibration Utilities Landsat TM
Spectral Preprocessing Data-Specific Utilities Landsat TM Landsat TM Calibration
The Input File dialog appears.

Select an input file and perform optional Spatial Subsetting and/or Spectral Subsetting, then click OK. The TM Calibration Parameters dialog appears.
For Landsat 7 HDF files, the data acquisition date information, gains and bias factors, and sun elevation and azimuth are automatically read from the header.

For Landsat 7 GeoTIFF files, you can obtain these parameters from the EROS Data Center as CPF files and MetaData files. You they may also acquire them through an ITT Visual Information Solutions web server (see step 3). The earth-sun distance used in Landsat-7 calibration is calculated from a table in the Landsat 7 User's Guide, dated May 1, 2001.

Choose from the following options:
Enter or change any of the parameters as necessary.

To download Landsat-7 parameters from the ITT Visual Information Solutions web server, use Get Calibration Parameters from Web, which is only available only when the file is in GeoTIFF format. You must have an active internet connection to use this option.

While a web browser can negotiate with the proxy server to access the ITT Visual Information Solutions site, ENVI establishes its own internet connection to the website and does not use a web browser. Your local network administrator may be able to allow your system to bypass the proxy to access the website. Currently, you cannot access this site through a firewall or proxy server. (If you try, your connection times out within 15 seconds.) See Manually Accessing Landsat-7 Calibration Parameters from the Web.

The information is obtained from the Web server and automatically entered into the corresponding fields.

If the input filename does not follow the Landsat 7 filenaming convention, the data acquisition date information defaults to January 1, 1984 and the sun elevation to 90 degrees. When the warning dialog appears, click OK. The TM Web Calibration Parameters dialog appears. Enter the original filename, or select the Date/Path/Row/Band button and enter the corresponding information.

The date, path, row, and band information is used to derive a filename based on the Landsat 7 naming convention.

Click OK.

For GeoTIFF files only, select an input band used for processing from the Data Acquisition Band drop-down list.

Select the output type using the Radiance or Reflectance radio buttons.

Provide Scale: Min and Scale: Max values if these values are not provided by a header or the Web server.

The minimum scale and maximum scale values are satellite parameters set for each band.ENVI uses these values to derive the gains and offsets.

Select output to File or Memory.

Click OK. When complete, ENVI adds the resulting output to the Available Bands List.