NAME

       shprewind - validates and resets the winding order of rings

SYNOPSIS

       shprewind in_shp_file out_shp_file

DESCRIPTION

       Validates  and  resets the winding order of rings in polygon geometries to match the ordering required by
       shapefile specification. This is useful for shapefiles having  troubles  when  checked  with  a  'shpdump
       -validate'.

       Makes  a  copy  of  the  shapefile in_shp_file to out_shp_file 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 in_shp_file and attempting to open the files in_shp_file.shp or
       in_shp_file.SHP, and in_shp_file.shx or in_shp_file.SHX for the respective  data  and  index  files.  The
       files  to  create  from out_shp_file are determined by stripping any filename extension from out_shp_file
       and appending .shp and .shx suffixes for the respective data and index files.

OPTIONS

       in_shp_file
              the name of an existing shapefile.

       out_shp_file
              the name of the new fixed shapefile that will be created.

EXIT STATUS

       0      Successful program execution.

       1      Missing in_shp_file or out_shp_file arguments, failed to  open  shapefile  in_shp_file  or  create
              shapefile out_shp_file.

DIAGNOSTICS

       The following diagnostics may be issued on stdout:

       Unable to open:in_shp_file

       Unable to create:out_shp_file

       count objects rewound.

EXAMPLE

       shprewind badshapefile newshapefile

AUTHOR

       shprewind  is  part  of  shapelib, maintained by Frank Warmerdam. This guide was created by Eduardo Patoo
       Kanegae and converted to manpage by Johan Van de Wauw. It was further enhanced with the man page  written
       by Joonas Pihlaja (jpihlaja@cc.helsinki.fi).

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),  dbfcat(1),  dbfcreate(1),  dbfdump(1),  dbfinfo(1),   shpadd(1),   shpcat(1),   shpcentrd(1),
       shpcreate(1), shpdump(1), shpdxf(1), shpfix(1), shpinfo(1), shpproj(1), shptest(1)

                                                  December 2023                                     SHPREWIND(1)