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i.landsat.acca(1)	    GRASS GIS User's Manual	     i.landsat.acca(1)

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

KEYWORDS
       imagery,	ACCA, cloud detection, satellite, Landsat

SYNOPSIS
       i.landsat.acca
       i.landsat.acca --help
       i.landsat.acca	[-5fx2s]   input=basename   output=name	   [b56compos-
       ite=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=basenameA [required]
	   Base	name of	input raster bands
	   Example: 'B.' for B.1, B.2, ...

       output=nameA [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,  out-
       putting 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 As-
	      sessment	(ACCA)	Algorithm. Photogrammetric Engineering and Re-
	      mote 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 Multispec-
	      tral, 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 Envi-
       ronmental Management, University	of LeA^3n, Spain

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

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

       A(C) 2003-2021 GRASS Development	Team, GRASS GIS	7.8.6 Reference	Manual

GRASS 7.8.6						     i.landsat.acca(1)

NAME | KEYWORDS | SYNOPSIS | DESCRIPTION | NOTES | EXAMPLES | REFERENCES | SEE ALSO | AUTHOR | SOURCE CODE

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