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

       1998-2022

                                           Jun 30, 2022                        GDAL_POLYGONIZE(1)