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 21:09:06 +0200 (Fri, 16 May 2008) $ Full index © 2003-2014 GRASS Development Team