gdal_sieve - Removes small raster polygons.
gdal_sieve.py [-q] [-st threshold] [-4] [-8] [-o name=value]
srcfile [-nomask] [-mask filename] [-of format] [dstfile]
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. Starting with GDAL 2.3, if not specified, the
format is guessed from the extension (previously was GTiff). Use the short
format name.
Frank Warmerdam warmerdam@pobox.com