NAME

       r.bitpattern  - Compares bit patterns with a raster map.

KEYWORDS

       raster, map algebra

SYNOPSIS

       r.bitpattern
       r.bitpattern help
       r.bitpattern  [-q]  input=name  output=name  pattern=integer patval=integer  [--overwrite]
       [--verbose]  [--quiet]

   Flags:
       -q
           Quiet

       --overwrite
           Allow output files to overwrite existing files

       --verbose
           Verbose module output

       --quiet
           Quiet module output

   Parameters:
       input=name
           Name of input raster map

       output=name
           Name for output raster map

       pattern=integer
           Bit pattern position(s)

       patval=integer
           Bit pattern value

DESCRIPTION

       r.bitpattern performs bit pattern comparisons.  The module can be used to pixelwise verify
       a  satellite  image  for low quality pixels if a Quality Control Bit Index map is provided
       (e.g. as for MODIS sensor maps).  The functionality is two-fold:

       1      define position: set bit(s) to 1 which shall  match,  then  convert  this  position
              pattern to integer, set pattern= parameter with that integer value

       2      define  pattern  *value*  which  should  be  in that position: first bit pattern of
              value, convert to integer, set patval= parameter

       If several bitpatterns have to be tested, the resulting maps can be used  to  exclude  low
       quality pixel in the input satellite image using r.mapcalc (OR and NOT operators).

EXAMPLE

       1      define position:
                   xx xx 1x xx
                   binary: 1000 -> integer: 8 -> pattern=8

       2      define value:
                      Ex.: we want to check for 0 in that position
                   xx xx 0x xx
                   binary: 0000 -> integer: 0 -> patval=0
                      if value can be arbitray (0/1), then assume 0 value

SEE ALSO

        r.mapcalc

AUTHORS

       Radim Blazek, Markus Neteler

       Last changed: $Date: 2008-05-16 12:09:06 -0700 (Fri, 16 May 2008) $

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