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NAME  - Converts a raster map into a vector map layer.


       raster, conversion, vectorization

SYNOPSIS help  [-svzbq]  input=name  output=name  feature=string   [--overwrite]   [--verbose]

           Smooth corners of area features

           Use raster values as categories instead of unique sequence (CELL only)

           Write raster values as z coordinate. Table is not created.  Currently  supported  only
           for points.

           Do not build vector topology (use with care for massive point export)

           Quiet - Do not show progress

           Allow output files to overwrite existing files

           Verbose module output

           Quiet module output

           Name of input raster map

           Name for output vector map

           Feature type
           Options: point,line,area
           Default: line

DESCRIPTION  scans  the  named  input  raster map layer, extracts points, lines or area edge
       features from it, converts data to GRASS vector format.

       The program extracts data from a GRASS raster map layer and stores output  in  a
       new GRASS vector file.

   Lines assumes that the input map has been thinned using r.thin.  extracts  vectors  (aka,  "arcs")  from a raster map.  These arcs may represent
       linear features (like roads or  streams),  or  may  represent  area  edge  features  (like
       political boundaries, or soil mapping units).

       r.thin  and  may create excessive nodes at every junction, and may create small
       spurs or "dangling lines" during the thinning and vectorization process.  These  excessive
       nodes and spurs may be removed using v.clean.

   Areas  first  traces  the  perimeter  of  each unique area in the raster map layer and
       creates vector data to represent it.  The cell category values for the  raster  map  layer
       will be used to create attribute information for the resultant vector area edge data.

       A true vector tracing of the area edges might appear blocky, since the vectors outline the
       edges of raster data that are stored in rectangular cells.  To  produce  a  better-looking
       vector map, smoothes the corners of the vector data as they are being extracted.
       At each change in direction (i.e., each corner), the two  midpoints  of  the  corner  cell
       (half the cell's height and width) are taken, and the line segment connecting them is used
       to outline this corner in the resultant  vector  map.   (The  cell's  cornermost  node  is
       ignored.)  Because vectors are smoothed by this program, the resulting vector map will not
       be "true" to the raster map from  which  it  was  created.   The  user  should  check  the
       resolution of the geographic region (and the original data) to estimate the possible error
       introduced by smoothing. extracts only area edges from the named raster input file.  If  the  raster  map
       contains other data (i.e., line edges, or point data) the output may be wrong.


       For  feature=line  the  input  raster map MUST be thinned by r.thin; if not, may


       Bill Brown
       Mike Baba
       DBA Systems, Inc.
       10560 Arrowhead Drive
       Fairfax, Virginia 22030
       Original version of r.poly:
       Jean Ezell and Andrew Heekin,
       U.S. Army Construction Engineering Research Laboratory

       Modified program for smoothed lines:
       David Satnik, Central Washington University
       Updated 2001 by Andrea Aime, Modena, Italy
       Original, r.line and r.poly merged and updated to 5.7 by Radim Blazek

       Last changed: $Date: 2008-05-16 12:09:06 -0700 (Fri, 16 May 2008) $

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       © 2003-2013 GRASS Development Team