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)

shapelib                                          OCTOBER 2004                                       SHAPELIB(1)