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NAME

       shprewind - fix polygon ring orientations in ESRI shapefiles

SYNOPSIS

       shprewind infile outfile

DESCRIPTION

       Makes  a  copy  of  the  shapefile  infile  to  outfile  and  fixes the
       orientation of points in the rings of Polygon, PolygonZ,  and  PolygonM
       typed  shapes  to conform to the shapefile specification.  According to
       the specification, the vertices  of  outer  rings  should  be  oriented
       clockwise  on the X/Y plane, and those of inner rings counterclockwise.

       Shapefiles actually consist of two files with  the  same  basename  and
       extensions  .shp and .shx  (or .SHP and .SHX) containing the shape data
       and shape index respectively.  The files  to  open  are  determined  by
       first  stripping  any  filename extension from infile and attempting to
       open the files infile.shp or infile.SHP, and infile.shx  or  infile.SHX
       for  the  respective  data  and  index files.  The files to create from
       outfile are determined by stripping any filename extension from outfile
       and  appending .shp and .shx suffixes for the respective data and index
       files.

EXIT STATUS

       0      Successful program execution.

       1      Missing infile or outfile arguments, failed  to  open  shapefile
              infile or create shapefile outfile.

DIAGNOSTICS

       The following diagnostics may be issued on stdout:

       Unable to open:infile

       Unable to create:outfile

       count objects rewound.

AUTHORS

       Frank Warmerdam (warmerdam@pobox.com) is the maintainer of the shapelib
       shapefile library.  Joonas Pihlaja (jpihlaja@cc.helsinki.fi) wrote this
       man page.

BUGS

       The implementation assumes that there is at most one outer ring in each
       shape, that it is the first ring in a shape, and all other rings  in  a
       shape  are  inner rings.  Polygons inside MultiPatch shape types aren’t
       rewound.

SEE ALSO

       dbfadd(1),   dbfcreate(1),    dbfdump(1),    dbf_dump(1),    shpadd(1),
       shpcreate(1), shpdump(1)