i.aster.toar.1grass man page

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


imagery, radiometric conversion, Terra-ASTER, radiance, reflectance, brightness temperature


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



Output is radiance (W/m2)


VNIR is High Gain


SWIR is High Gain


VNIR is Low Gain 1


SWIR is Low Gain 1


SWIR is Low Gain 2


Allow output files to overwrite existing files


Print usage summary


Verbose module output


Quiet module output


Force launching GUI dialog


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)


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 after importing your Aster imagery from storage format 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.


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


Yann Chemin, CSU, Australia

Last changed: $Date: 2014-12-09 18:31:29 +0100 (Tue, 09 Dec 2014) $

Main index | Imagery index | Topics index | Keywords index | Full index

© 2003-2016 GRASS Development Team, GRASS GIS 7.0.4 Reference Manual


GRASS 7.0.4 Grass User's Manual