NAME

       gdal_polygonize - Produces a polygon feature layer from a raster.

SYNOPSIS

          gdal_polygonize [--help] [--help-general]
                             [-8] [-o <name>=<value>]... [-nomask]
                             [-mask <filename>] <raster_file> [-b <band>]
                             [-q] [-f <ogr_format>] [-lco <name>=<value>]...
                             [-overwrite] <out_file> [<layer>] [<fieldname>]

DESCRIPTION

       This  utility  creates vector polygons for all connected regions of pixels in the raster sharing a common
       pixel value.  Each polygon is created with an attribute indicating the pixel value of  that  polygon.   A
       raster mask may also be provided to determine which pixels are eligible for processing.

       The  utility will create the output vector datasource if it does not already exist, otherwise it will try
       to append to an existing one.

       The utility is based on the :GDALPolygonize() function which has additional details on the algorithm.

       NOTE:
          gdal_polygonize is a Python utility, and is only available if GDAL Python bindings are available.

       --help Show this help message and exit

       --help-general
              Gives a brief usage message for the generic GDAL commandline options and exit.

       -8     Use 8 connectedness. Default is 4 connectedness.

       -nomask
              Do not use the default validity mask for the input band (such as nodata, or alpha masks).

       -mask <filename>
              Use the first band of the specified file as a validity mask (zero is invalid, non-zero is  valid).
              If  not  specified,  the default validity mask for the input band (such as nodata, or alpha masks)
              will be used (unless -nomask is specified)

       <raster_file>
              The source raster file from which polygons are derived.

       -b <band>
              The band on <raster_file> to build the polygons from. The value can also  be  set  to  "mask",  to
              indicate  that the mask band of the first band must be used (or "mask,band_number" for the mask of
              a specified band)

       -f <ogr_format>
              Select the output format. If not specified, the format is guessed  from  the  extension.  Use  the
              short format name

       -o <NAME>=<VALUE>
              Added in version 3.7.

              Polygonize option. See :GDALPolygonize() documentation.

       -lco <NAME>=<VALUE>
              Added in version 3.7.

              Layer creation option (format specific)

       -overwrite
              Added in version 3.8.

              Overwrite the output layer if it already exists.

       <out_file>
              The destination vector file to which the polygons will be written.

       <layer>
              The name of the layer created to hold the polygon features.

       <fieldname>
              The name of the field to create (defaults to "DN").

       -q     The  script  runs  in quiet mode.  The progress monitor is suppressed and routine messages are not
              displayed.

AUTHOR

       Frank Warmerdam <warmerdam@pobox.com>

COPYRIGHT

       1998-2025

                                                  Nov 07, 2025                                GDAL_POLYGONIZE(1)