NAME

       i.aster.toar   -  Calculates Top of Atmosphere Radiance/Reflectance/Brightness Temperature
       from ASTER DN.

KEYWORDS

       imagery, radiometric conversion, radiance, reflectance, brightness temperature, satellite,
       ASTER

SYNOPSIS

       i.aster.toar
       i.aster.toar --help
       i.aster.toar    [-rabcde]    input=name[,name,...]   dayofyear=float   sun_elevation=float
       output=name  [--overwrite]  [--help]  [--verbose]  [--quiet]  [--ui]

   Flags:
       -r
           Output is radiance (W/m2)

       -a
           VNIR is High Gain

       -b
           SWIR is High Gain

       -c
           VNIR is Low Gain 1

       -d
           SWIR is Low Gain 1

       -e
           SWIR is Low Gain 2

       --overwrite
           Allow output files to overwrite existing files

       --help
           Print usage summary

       --verbose
           Verbose module output

       --quiet
           Quiet module output

       --ui
           Force launching GUI dialog

   Parameters:
       input=name[,name,...] [required]
           Names of ASTER DN layers (15 layers)

       dayofyear=float [required]
           Day of Year of satellite overpass [0-366]

       sun_elevation=float [required]
           Sun elevation angle (degrees, < 90.0)

       output=name [required]
           Base name of the output layers (will add .x)

DESCRIPTION

       i.aster.toar calculates the Top Of Atmosphere (TOA) reflectance for Terra-ASTER L1B in the
       visible,  NIR  and  SWIR bands (9+1 bands) and brightness temperature for the TIR bands (5
       bands), all from L1B DN values.  It is useful to apply  after  import  of  original  ASTER
       imagery that is generally in standard DN values range.

       The order of input bands is

           •   VNIR: 1,2,3N,3B

           •   SWIR: 4,5,6,7,8,9

           •   TIR: 10,11,12,13,14
       in one comma-separated list.

NOTES

       Internally,  a  gain code is defined to modify gains according to spectral bands following
       the GeoSystems GmbH ATCOR  Ver.  2.0  Calibration  Files.   The  function  is  defined  in
       gain_aster.c file.
       /*Gain Code*/
           /*0 - High (Not Applicable for band 10-14: TIR)*/
           /*1 - Normal*/
           /*2 - Low 1(Not Applicable for band 10-14: TIR)*/
           /*3 - Low 2(Not Applicable for Band 1-3N/B and 10-14)*/

SEE ALSO

        i.landsat.toar, r.in.aster

       ASTER  sensor  data  download:  ASTER: Advanced Spaceborne Thermal Emission and Reflection
       Radiometer

AUTHOR

       Yann Chemin, CSU, Australia

SOURCE CODE

       Available at: i.aster.toar source code (history)

       Accessed: Thursday Aug 01 11:31:29 2024

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       © 2003-2024 GRASS Development Team, GRASS GIS 8.4.0 Reference Manual