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)