NAME
s.to.poly.sh - create coarse-grained area vectors
from a site file
(GRASS Shell Script)
SYNOPSIS
s.to.poly.sh input=sitefile output=vectormap
[ filter=filterfile | filter=none ]
[ maxpoly=n ]
[ maxiter=n ]
DESCRIPTION
s.to.poly.sh
is a UNIX Bourne shell to create coarse-grained polygons that surround
site data. s.to.poly.sh differs from convex hull operations available in
s.geom in that s.to.poly.sh allows site data to clump into several polygons,
rather than a single polygon surrounding around all sites.
s.to.poly.sh first converts site data into an intermediate raster map,
and the filters the raster using r.mfilter to remove isolated
points. See the notes section for the default filter used. Any other filter
may be used by specifing the filter= option, or no filtering by
specifing filter=none.
Next, the raster data is converted into area vectors with r.poly and the
number of unique polygons are counted. If the number of polygons is
greater than the number specified with maxpoly=n, the raster is
grown using r.grow. Processing continues until either the number of
polygons is less than or equal to the number requested in maxpoly=n,
or until the maximum number of iterations has been reached, specified
with maxiter=n.
OPTIONS
Parameters:
- input=sitefile
- The name a site file.
- output=vectormap
- The name of the resulting vector map. The new vector map is created
in the currently selected mapset and database.
Optional parameters:
- filter=filterfile or filter=none
- The name of a filter (r.mfilter format) to preprocess site data after
conversion into an intermediate raster map. Specify none to skip
filtering. The default filter is listed in the notes section.
- maxpoly=n
- The number of desired polygons in the resulting vector map. The default
is 99999.
- maxiter=n
- The number of iterations of converting the site data to area vectors.
The default is 5.
NOTES
Environment variables GISBASE , GISDBASE ,
LOCATION_NAME and MAPSET are used to specify the GRASS
database, location, and mapset.
The default filter used to smooth site data is:
MATRIX 11
1 1 1 1 1 1 1 1 1 1 1
1 1 1 2 2 2 2 2 1 1 1
1 1 2 2 3 3 3 2 2 1 1
1 2 2 3 3 3 3 3 2 2 1
1 2 3 3 0 0 0 3 3 2 1
1 2 3 3 0 0 0 3 3 2 1
1 2 3 3 0 0 0 3 3 2 1
1 2 2 3 3 3 3 3 2 2 1
1 1 2 2 3 3 3 2 2 1 1
1 1 1 2 2 2 2 2 1 1 1
1 1 1 1 1 1 1 1 1 1 1
DIVISOR 50
TYPE P
EOF
Several intermediate raster maps are created and removed during
processing.
FILES
SEE ALSO
s.to.rast
r.mfilter
r.grow
r.poly
r.mapcalc
s.geom
AUTHOR
Tom Poindexter, February, 2000
tpoindex@nyx.net