NAME

       gdal_sieve - Removes small raster polygons.

SYNOPSIS

       gdal_sieve.py [-q] [-st threshold] [-4] [-8] [-o name=value]
                  srcfile [-nomask] [-mask filename] [-of format] [dstfile]

DESCRIPTION

       The gdal_sieve.py script removes raster polygons smaller than a provided threshold size (in pixels) and
       replaces replaces them with the pixel value of the largest neighbour polygon. The result can be written
       back to the existing raster band, or copied into a new file.

       The input dataset is read as integer data which means that floating point values are rounded to integers.
       Re-scaling source data may be necessary in some cases (e.g. 32-bit floating point data with min=0 and
       max=1).

       Additional details on the algorithm are available in the GDALSieveFilter() docs.

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

       -st threshold:
           Set the size threshold in pixels. Only raster polygons smaller than this size will be removed.

       -o name=value:
           Specify a special argument to the algorithm. Currently none are supported.

       -4:
           Four connectedness should be used  when  determining  polygons.  That  is  diagonal  pixels  are  not
           considered directly connected. This is the default.

       -8:
           Eight  connectedness should be used when determining polygons. That is diagonal pixels are considered
           directly connected.

       srcfile
           The source raster file used to identify target pixels. Only the first band is used.

       -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).

       dstfile
           The new file to create with the filtered result. If not provided,  the  source  band  is  updated  in
           place.

       -of format:
           Select the output format. The default is GeoTIFF (GTiff). Use the short format name.

AUTHORS

       Frank Warmerdam warmerdam@pobox.com

GDAL                                             Tue Feb 6 2018                                    gdal_sieve(1)