Raster Meets Vector Data - Open Source Geospatial Tools: Applications in Earth Observation - page 134

9.4 gdal_contour

The gdal_contour utility converts a raster to a vector dataset. It hereby creates
contour (or iso-) lines connecting pixels with similar values. The thresholds used for
similarity can be set using the options -i and -fl . Pixel values below this threshold
are considered as background and will be ignored. With the option -i , you can set
the thresholds as multiples of the defined interval level. For more flexibility, you can
set your own levels using the option -fl . A typical use of gdal_contour is to
create height contour lines from a digital elevation model (DEM).

Usage: gdal_contour [-b <band>] [-a <attribute_name>] [-3d]
→ [-inodata] [-snodata n] [-i <interval>] [-f <formatname>]

→ [[-dsco NAME=VALUE] ...] [[-lco NAME=VALUE] ...] [-off

→ <offset>] [-fl <level> <level>...] [-nln <outlayername>]

→ <src_filename> <dst_filename>

-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.
-3d
Force production of 3D vectors instead of 2D. Includes elevation at every vertex.
-inodata
Ignore any no-data value implied in the dataset - treat all values as valid.
-snodata value
Input pixel value to treat as "no-data".
-f format
create output in a particular format, default is Shapefile.
-dsco NAME=VALUE
Dataset creation option (format specific).
-lco NAME=VALUE
Layer creation option (format specific).
-i interval
elevation interval between contours.
-off offset
Offset from zero relative to which to interpret intervals.
-fl level
Name one or more “fixed levels” to extract.
-nln outlayername
Provide a name for the output vector layer. Defaults to “contour”.