r.bitpattern(1)

NAME
r.bitpattern

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

© 2003-2011 GRASS Development Team