DESCRIPTION
This module creates a raster map containing concentric rings around a given
point. The cell values are increasing linear from the center point to outer
rings. Minimum and maximum radius can be selected. Optionally a "donut" ring
can be created to use as (binary) filter for i.ifft inverse Fourier
transform (apply filter with r.mask).
EXAMPLES
Generate a circle at current map center with a radius of 300m:
EASTCENTER=`g.region -c | awk ' /region center easting:/ { print $4 }'`
NORTHCENTER=`g.region -c | awk ' /region center northing:/ { print $4 }'`
r.circle -b out=circle coordinate=$EASTCENTER,$NORTHCENTER max=300
SEE ALSO
g.remove,
g.rename,
i.fft,
i.ifft
AUTHOR
Bill Brown, U.S. Army Construction Engineering Research Laboratory
Additional flag/min/max parameter by Markus Neteler, University of Hannover
Last changed: $Date$