NAME

       r.circle  - Creates a raster map containing concentric rings around a given point.

KEYWORDS

       raster, geometry

SYNOPSIS

       r.circle
       r.circle help
       r.circle   [-b]   output=name  coordinate=x,y   [min=float]    [max=float]    [mult=float]
       [--overwrite]  [--verbose]  [--quiet]

   Flags:
       -b
           Generate binary raster map

       --overwrite
           Allow output files to overwrite existing files

       --verbose
           Verbose module output

       --quiet
           Quiet module output

   Parameters:
       output=name
           Name for output raster map

       coordinate=x,y
           The coordinate of the center (east,north)

       min=float
           Minimum radius for ring/circle map (in meters)

       max=float
           Maximum radius for ring/circle map (in meters)

       mult=float
           Data value multiplier

DESCRIPTION

       This module creates an output raster map centered on the x,y  values  specified  with  the
       coordinate  parameter,  out  to  the  edge  of the current region.  The output cell values
       increase linearly from the specified center. The min and max parameters control the  inner
       and outer output raster map radii, respectively.

       The  mult  parameter  can  be used to multiply the output raster cells by a common factor.
       Note that this parameter does not affect the output raster position or size; only  the  z-
       values are changed with this parameter.

       Binary-output  raster  maps  (solid circles of one value) can be created with the -b flag.
       Raster maps so created can be used to create binary filters for  use  in  i.ifft  (inverse
       Fourier transformations; apply filter with r.mask).

EXAMPLES

       Generate  a  raster  circle  at  current  map  center  with a radius of 300m and outwardly
       increasing raster values:
       EASTCENTER=`g.region -c |  awk ' /center easting:/ { print $3 }'`
       NORTHCENTER=`g.region -c | awk ' /center northing:/ { print $3 }'`
       r.circle output=circle coordinate=${EASTCENTER},${NORTHCENTER} max=300
        Generate a binary raster ring around current map center with an inner radius of 500m  and
       an outer radius of 1000m:
       EASTCENTER=`g.region -c |  awk ' /center easting:/ { print $3 }'`
       NORTHCENTER=`g.region -c | awk ' /center northing:/ { print $3 }'`
       r.circle -b output=circle coordinate=${EASTCENTER},${NORTHCENTER} min=500 max=1000

SEE ALSO

        g.region, g.remove, g.rename, i.fft, i.ifft, r.mask

AUTHOR

       Bill Brown, U.S. Army Construction Engineering Research Laboratory
       Additional flag/min/max parameter by Markus Neteler, University of Hannover

       Last changed: $Date: 2009-01-05 14:04:18 -0800 (Mon, 05 Jan 2009) $

       Full index

       © 2003-2013 GRASS Development Team