GRASS logo

Note: A new GRASS GIS stable version has been released: GRASS GIS 7.6, available here.
Updated manual page: here


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


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


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)

Table of contents


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

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)*/



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


Yann Chemin, CSU, Australia

Last changed: $Date: 2016-05-18 00:07:29 -0700 (Wed, 18 May 2016) $


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

Note: A new GRASS GIS stable version has been released: GRASS GIS 7.6, available here.
Updated manual page: here

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

© 2003-2019 GRASS Development Team, GRASS GIS 7.4.5svn Reference Manual