GDAL-VECTOR-GEOM-SIMPLIFY(1)         GDAL         GDAL-VECTOR-GEOM-SIMPLIFY(1)

NAME
       gdal-vector-geom-simplify - Simplify geometries of a vector dataset

       Added in version 3.11.


SYNOPSIS

          Usage: gdal vector geom simplify [OPTIONS] <INPUT> <OUTPUT> <TOLERANCE>

          Simplify geometries of a vector dataset.

          Positional arguments:
            -i, --input <INPUT>                                  Input vector datasets [required]
            -o, --output <OUTPUT>                                Output vector dataset [required]
            --tolerance <TOLERANCE>                              Distance tolerance for simplification. [required]

          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]
            --progress                                           Display progress bar

          Options:
            -l, --layer, --input-layer <INPUT-LAYER>             Input layer name(s) [may be repeated]
            -f, --of, --format, --output-format <OUTPUT-FORMAT>  Output format ("GDALG" allowed)
            --co, --creation-option <KEY>=<VALUE>                Creation option [may be repeated]
            --lco, --layer-creation-option <KEY>=<VALUE>         Layer creation option [may be repeated]
            --overwrite                                          Whether overwriting existing output is allowed
            --update                                             Whether to open existing dataset in update mode
            --overwrite-layer                                    Whether overwriting existing layer is allowed
            --append                                             Whether appending to existing layer is allowed
            --output-layer <OUTPUT-LAYER>                        Output layer name
            --active-layer <ACTIVE-LAYER>                        Set active layer (if not specified, all)
            --active-geometry <ACTIVE-GEOMETRY>                  Geometry field name to which to restrict the processing (if not specified, all)

          Advanced Options:
            --if, --input-format <INPUT-FORMAT>                  Input formats [may be repeated]
            --oo, --open-option <KEY>=<VALUE>                    Open options [may be repeated]

DESCRIPTION
       gdal vector geom simplify simplify geometries, ensuring that the result
       is a valid geometry having the same dimension and number of components
       as the input.

       The simplification uses a maximum distance difference algorithm similar
       to the one used in the Douglas-Peucker algorithm.

       This done by the OGRGeometry::SimplifyPreserveTopology() method which
       preserves the topology per feature, but not for a whole layer.  Thus
       gaps or overlaps between geometries that were initially contiguous may
       happen.

       This command can also be used as a step of gdal vector pipeline.

       NOTE:
          This command requires a GDAL build against the GEOS library.

   Standard options

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

       --co <NAME>=<VALUE>
              Many formats have one or more optional dataset creation options
              that can be used to control particulars about the file created.
              For instance, the GeoPackage driver supports creation options to
              control the version.

              May be repeated.

              The dataset creation options available vary by format driver,
              and some simple formats have no creation options at all. A list
              of options supported 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 Vector drivers format specific
              documentation for legal creation options for each format.

              Note that dataset creation options are different from layer
              creation options.

       -lco <NAME>=<VALUE>
              Layer creation option (format specific)

       --overwrite
              Allow program to overwrite existing target file or dataset.
              Otherwise, by default, gdal errors out if the target file or
              dataset already exists.

       --active-layer <ACTIVE-LAYER>
              Set the active layer. When it is specified, only the layer
              specified by its name will be subject to the processing. Other
              layers will be not modified.  If this option is not specified,
              all layers will be subject to the processing.

       --active-geometry <ACTIVE-GEOMETRY>
              Set the active geometry field from its name. When it is
              specified, only the specified geometry field will be subject to
              the processing. Other geometry fields will be not modified.  If
              this option is not specified, all geometry fields will be
              subject to the processing.  This option can be combined together
              with --active-layer.

       --tolerance <TOLERANCE>
              The specified value of this option is the tolerance used to
              merge consecutive points of the output geometry using the
              OGRGeometry::SimplifyPreserveTopology() method The unit of the
              distance is in georeferenced units of the source layer.

   Advanced options

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

              May be repeated.

       --if <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 several 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.

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
       vector dataset using the GDALG: GDAL Streamed Algorithm driver, and
       apply the specified pipeline in a on-the-fly / streamed way.

EXAMPLES
   Example 1: Simplify geometries using a tolerance of one km (assuming the
       CRS is in meters)

          $ gdal vector geom simplify --tolerance=1000 in.gpkg out.gpkg --overwrite

AUTHOR
       Even Rouault <even.rouault@spatialys.com>

COPYRIGHT
       1998-2025

                                  May 6, 2025     GDAL-VECTOR-GEOM-SIMPLIFY(1)