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NAME

       i.landsat.acca  - Performs Landsat TM/ETM+ Automatic Cloud Cover Assessment (ACCA).

KEYWORDS

       imagery, ACCA, cloud detection, satellite, Landsat

SYNOPSIS

       i.landsat.acca
       i.landsat.acca --help
       i.landsat.acca      [-5fx2s]      input=basename     output=name      [b56composite=float]
       [b45ratio=float]   [histogram=integer]   [--overwrite]  [--help]   [--verbose]   [--quiet]
       [--ui]

   Flags:
       -5
           Data is Landsat-5 TM
           I.e. Thermal band is ’.6’ not ’.61’)

       -f
           Apply post-processing filter to remove small holes

       -x
           Always use cloud signature (step 14)

       -2
           Bypass second-pass processing, and merge warm (not ambiguous) and cold clouds

       -s
           Include a category for cloud shadows

       --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=basename [required]
           Base name of input raster bands
           Example: ’B.’ for B.1, B.2, ...

       output=name [required]
           Name for output raster map

       b56composite=float
           B56composite (step 6)
           Default: 225.

       b45ratio=float
           B45ratio: Desert detection (step 10)
           Default: 1.

       histogram=integer
           Number of classes in the cloud temperature histogram
           Default: 100

DESCRIPTION

       i.landsat.acca implements the Automated Cloud-Cover Assessment (ACCA) Algorithm from Irish
       (2000) with the constant values for pass filter one from Irish et al. (2006). To do  this,
       it needs Landsat band numbers 2, 3, 4, 5, and 6 (or band 61 for Landsat-7 ETM+) which have
       already  been  processed  from  DN  into   reflectance   and   band-6   temperature   with
       i.landsat.toar).

       The  ACCA  algorithm  gives good results over most of the planet with the exception of ice
       sheets because ACCA operates on the premise that clouds are colder than the  land  surface
       they  cover. The algorithm was designed for Landsat-7 ETM+ but because reflectance is used
       it is also useful for Landsat-4/5 TM.

NOTES

       i.landsat.acca works in the current region settings.

EXAMPLES

       Run the standard ACCA algorithm with filling of small cloud  holes  (the  -f  flag):  With
       per-band  reflectance raster maps named 226_62.toar.1, 226_62.toar.2,  [...] and LANDSAT-7
       thermal band 226_62.toar.61, outputting to a new raster map named 226_62.acca:
       i.landsat.toar sensor=7 gain=HHHLHLHHL date=2003-04-07 \
         product_date=2008-11-27 band_prefix=226_62 solar_elevation=49.51654
       i.landsat.acca -f band_prefix=226_62.toar output=226_62.acca

REFERENCES

       1      Irish R.R., Barker J.L., Goward S.N., and Arvidson T., 2006.   Characterization  of
              the   Landsat-7   ETM+   Automated   Cloud-Cover   Assessment   (ACCA)   Algorithm.
              Photogrammetric Engineering and Remote Sensing vol. 72(10): 1179-1188.

       2      Irish, R.R., 2000. Landsat 7 Automatic Cloud Cover Assessment.  In  S.S.  Shen  and
              M.R. Descour (Eds.): Algorithms for Multispectral, Hyperspectral, and Ultraspectral
              Imagery VI. Proceedings of SPIE, 4049: 348-355.

SEE ALSO

        i.atcorr, i.landsat.toar

AUTHOR

       E. Jorge Tizado  (ej.tizado unileon es), Dept. Biodiversity and Environmental  Management,
       University of León, Spain

       Last changed: $Date: 2017-11-26 11:44:34 +0100 (Sun, 26 Nov 2017) $

SOURCE CODE

       Available at: i.landsat.acca source code (history)

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       © 2003-2019 GRASS Development Team, GRASS GIS 7.6.1 Reference Manual