NAME

       gdal_polygonize - Produces a polygon feature layer from a raster.

SYNOPSIS

          gdal_polygonize.py [-8] [-nomask] [-mask filename] <raster_file> [-b band]
                             [-q] [-f ogr_format] <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, defaulting to GML
       format.

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

       -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. Starting with GDAL 2.2, 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. Starting with GDAL 2.3, if not specified, the format is guessed from the
              extension (previously was GML). Use the short format name

       <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

       1998-2021

                                                  Dec 27, 2021                                GDAL_POLYGONIZE(1)