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GDAL-RASTER-SIEVE(1)		      GDAL		    GDAL-RASTER-SIEVE(1)

NAME
     gdal-raster-sieve - Remove small raster polygons

     Added in version 3.11.

SYNOPSIS
	Usage: gdal raster sieve [OPTIONS] <INPUT> <OUTPUT>

	Remove small polygons from a raster dataset.

	Positional arguments:
	  -i, --input <INPUT>				       Input raster datasets [required] [not available in pipelines]
	  -o, --output <OUTPUT> 			       Output raster dataset [required] [not available in pipelines]

	Common Options:
	  -h, --help					       Display help message and exit
	  --json-usage					       Display usage as JSON document and exit
	  --config <KEY>=<VALUE>			       Configuration option [may be repeated]
	  -q, --quiet					       Quiet mode (no progress bar or warning message) [not available in pipelines]

	Options:
	  -f, --of, --format, --output-format <OUTPUT-FORMAT>  Output format ("GDALG" allowed) [not available in pipelines]
	  --co, --creation-option <KEY>=<VALUE> 	       Creation option [may be repeated] [not available in pipelines]
	  --overwrite					       Whether overwriting existing output dataset is allowed [not available in pipelines]
							       Mutually exclusive with --append
	  --append					       Append as a subdataset to existing output [not available in pipelines]
							       Mutually exclusive with --overwrite
	  --mask <MASK> 				       Use the first band of the specified file as a validity mask (all pixels with a value other than zero will be considered suitable for inclusion in polygons)
	  -b, --band <BAND>				       Input band (1-based index)
	  -s, --size-threshold <SIZE-THRESHOLD> 	       Minimum size of polygons to keep (default: 2)
	  -c, --connect-diagonal-pixels 		       Consider diagonal pixels as connected

	Advanced Options:
	  --if, --input-format <INPUT-FORMAT>		       Input formats [may be repeated] [not available in pipelines]
	  --oo, --open-option <KEY>=<VALUE>		       Open options [may be repeated] [not available in pipelines]

DESCRIPTION
     gdal raster sieve removes raster polygons smaller than a provided threshold
     size  (in	pixels)  and  replaces	them with the pixel value of the largest
     neighbour polygon.

     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).

     This subcommand is also available	as  a  potential  step	of  gdal  raster
     pipeline (since GDAL 3.12)

     Added in version 3.12.

GDALG OUTPUT (ON-THE-FLY / STREAMED DATASET)
     This program supports serializing the command line as a JSON file using the
     GDALG  output  format.   The  resulting file can then be opened as a raster
     dataset using the GDALG: GDAL Streamed  Algorithm	driver,  and  apply  the
     specified pipeline in a on-the-fly / streamed way.

     NOTE:
	However  this  algorithm  is  not  natively streaming compatible. Conse-
	quently a temporary dataset will be generated, which may cause	signifi-
	cant processing time at opening.

PROGRAM-SPECIFIC OPTIONS
     -b, --band <BAND>
	    Input band (1-based index)

     -c, --connect-diagonal-pixels
	    Consider  diagonal pixels (pixels at the corners) as connected.  The
	    default behavior is to only consider pixels that  are  touching  the
	    edges  as  connected, which is the same as 4-connectivity. When this
	    option is selected, the algorithm will also consider pixels  at  the
	    corners as connected, which is the same as 8-connectivity.

     --mask <MASK>
	    Use  the  first  band  of the specified file as a validity mask: all
	    pixels in the mask band with a value other than zero will be consid-
	    ered suitable for inclusion in polygons.

     -s, --size-threshold <SIZE-THRESHOLD>
	    Minimum size of polygons to keep (default: 2)

STANDARD OPTIONS
     --append
	    Append input raster as a new subdataset to an existing output  file.
	    Only  works  with  drivers	that  support adding subdatasets such as
	    GTiff -- GeoTIFF File Format and GPKG -- GeoPackage raster This also
	    creates the output dataset if it does not exist yet.

     --co, --creation-option <NAME>=<VALUE>
	    Many formats have one or more optional creation options that can  be
	    used  to  control  particulars about the file created. For instance,
	    the GeoTIFF driver supports creation options to control compression,
	    and whether the file should be tiled.

	    May be repeated.

	    The creation options available vary by format driver, and some  sim-
	    ple  formats have no creation options at all. A list of options sup-
	    ported for a format can be listed with the	--formats  command  line
	    option but the documentation for the format is the definitive source
	    of	information on driver creation options.  See Raster drivers for-
	    mat specific documentation for legal creation options for each  for-
	    mat.

     --if, --input-format <format>
	    Format/driver  name to be attempted to open the input file(s). It is
	    generally not necessary to specify it, but it can be  used	to  skip
	    automatic  driver detection, when it fails to select the appropriate
	    driver.  This option can be repeated several times to  specify  sev-
	    eral  candidate  drivers.  Note that it does not force those drivers
	    to open the dataset. In particular, some drivers  have  requirements
	    on file extensions.

	    May be repeated.

     --oo, --open-option <NAME>=<VALUE>
	    Dataset open option (format specific).

	    May be repeated.

     -f, --of, --format, --output-format <OUTPUT-FORMAT>
	    Which  output  raster  format to use. Allowed values may be given by
	    gdal --formats | grep raster | grep rw | sort

     --overwrite
	    Allow program to overwrite existing target file or dataset.   Other-
	    wise,  by default, gdal errors out if the target file or dataset al-
	    ready exists.

RETURN STATUS CODE
     The program returns status code 0 in case of success, and non-zero in  case
     of  error (non-blocking errors emitted as warnings are considered as a suc-
     cessful execution).

EXAMPLES
   Example 1: Remove polygons smaller than 10  pixels  from  the  band	2  of  a
     raster.
	$ gdal raster sieve -b 2 -s 10 input.tif output.tif

AUTHOR
     Alessandro Pasotti <elpaso@itopen.it>

COPYRIGHT
     1998-2026

				  Jun 05, 2026		    GDAL-RASTER-SIEVE(1)

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