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i.aster.toar

Calculates Top of Atmosphere Radiance/Reflectance/Brightness Temperature from ASTER DN.

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

Example:

i.aster.toar input=name dayofyear=float sun_elevation=float output=name

grass.script.run_command("i.aster.toar", input, dayofyear, sun_elevation, output, flags=None, overwrite=False, verbose=False, quiet=False, superquiet=False)

Example:

gs.run_command("i.aster.toar", input="name", dayofyear=float, sun_elevation=float, output="name")

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)
-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
--qq
    Very quiet module output
--ui
    Force launching GUI dialog

input : str | list[str], required
    Names of ASTER DN layers (15 layers)
    Used as: input, raster, name
dayofyear : float, required
    Day of Year of satellite overpass [0-366]
sun_elevation : float, required
    Sun elevation angle (degrees, < 90.0)
output : str, required
    Base name of the output layers (will add .x)
    Used as: output, raster, name
flags : str, optional
    Allowed values: r, a, b, c, d, e
    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: bool, optional
    Allow output files to overwrite existing files
    Default: False
verbose: bool, optional
    Verbose module output
    Default: False
quiet: bool, optional
    Quiet module output
    Default: False
superquiet: bool, optional
    Very quiet module output
    Default: False

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)
Latest change: Wednesday Apr 02 17:48:37 2025 in commit 571253a