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  brigthness  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)

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       © 2003-2019 GRASS Development Team, GRASS GIS 7.8.2 Reference Manual