NAME

       gdal_contour - Builds vector contour lines from a raster elevation model.

SYNOPSIS

          gdal_contour [--help] [--help-general]
                       [-b <band>] [-a <attribute_name>] [-amin <attribute_name>] [-amax <attribute_name>]
                       [-3d] [-inodata] [-snodata <n>] [-f <formatname>] [-i <interval>]
                       [-dsco <NAME>=<VALUE>]... [-lco <NAME>=<VALUE>]...
                       [-off <offset>] [-fl <level> <level>...] [-e <exp_base>]
                       [-nln <outlayername>] [-q] [-p] [-gt <n>|unlimited]
                       <src_filename> <dst_filename>

DESCRIPTION

       The gdal_contour generates a vector contour file from the input raster elevation model (DEM).

       The  contour  line-strings  are oriented consistently and the high side will be on the right, i.e. a line
       string goes clockwise around a top.

       --help Show this help message and exit

       --help-general
              Gives a brief usage message for the generic GDAL commandline options and exit.

       -b <band>
              Picks a particular band to get the DEM from. Defaults to band 1.

       -a <name>
              Provides a name for the attribute in which to put the elevation.  If  not  provided  no  elevation
              attribute is attached.  Ignored in polygonal contouring (-p) mode.

       -amin <name>
              Provides a name for the attribute in which to put the minimum elevation of contour polygon. If not
              provided no minimum elevation attribute is attached. Ignored in default line contouring mode.

              New in version 2.4.0.

       -amax <name>
              Provides a name for the attribute in which to put the maximum elevation of contour polygon. If not
              provided no maximum elevation attribute is attached.  Ignored in default line contouring mode.

              New in version 2.4.0.

       -3d    Force production of 3D vectors instead of 2D.  Includes elevation at every vertex.

       -inodata
              Ignore any nodata value implied in the dataset - treat all values as valid.

       -snodata <value>
              Input pixel value to treat as "nodata".

       -f <format>
              Create output in a particular format.

              New  in  version 2.3.0: If not specified, the format is guessed from the extension (previously was
              ESRI Shapefile).

       -dsco <NAME>=<VALUE>
              Dataset creation option (format specific)

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

       -i <interval>
              Elevation interval between contours.  Must specify either -i or -fl or -e.

       -off <offset>
              Offset from zero relative to which to interpret intervals.

              For example, -i 100 requests contours at ...-100, 0, 100...  Further adding  -off  25  makes  that
              request instead ...-75, 25, 125...

       -fl <level>
              Name one or more "fixed levels" to extract.

       -e <base>
              Generate  levels  on  an exponential scale: base ^ k, for k an integer.  Must specify either -i or
              -fl or -e.

              New in version 2.4.0.

       -nln <name>
              Provide a name for the output vector layer. Defaults to "contour".

       -p     Generate contour polygons rather than contour lines.

              New in version 2.4.0.

       -gt <n>
              Group n features per transaction (default 100 000). Increase the value for better performance when
              writing into DBMS drivers that have transaction support. n can be set to  unlimited  to  load  the
              data into a single transaction. If set to 0, no explicit transaction is done.

              New in version 3.10.

       -q     Be quiet: do not print progress indicators.

C API

       Functionality of this utility can be done from C with GDALContourGenerate().

EXAMPLE

       This  would  create  10-meter  contours  from  the  DEM  data  in  dem.tif  and  produce  a  shapefile in
       contour.shp|shx|dbf with the contour elevations in the elev attribute.

          gdal_contour -a elev dem.tif contour.shp -i 10.0

AUTHOR

       Frank Warmerdam <warmerdam@pobox.com>, Silke Reimer <silke@intevation.de>

COPYRIGHT

       1998-2025

                                                  Apr 01, 2025                                   GDAL_CONTOUR(1)