NAME

       gdal_contourBuilds vector contour lines from a raster elevation model.

SYNOPSIS

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

DESCRIPTION

       This program generates a vector contour file from the input raster elevation model (DEM).

       Starting from version 1.7 the contour line-strings will be oriented consistently. The high side will be
       on the right, i.e. a line string goes clockwise around a top.

       -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:
           (Since GDAL 2.4) 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.

       -amax name:
           (Since GDAL 2.4) provides a name for the attribute in which to put the maximum elevation  of  contour
           polygon.  If  not  provided  no  maximim  elevation  attribute  is  attached. Ignored in default line
           contouring mode.

       -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. Starting with GDAL 2.3, 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.

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

       -fl level:
           Name one or more 'fixed levels' to extract.

       -e base:
           (Since GDAL 2.4) will generate levels on an exponential scale: base ^ k, for k an integer.

       -nln outlayername:
           Provide a name for the output vector layer. Defaults to 'contour'.

       -p:
           (Since GDAL 2.4) Generate contour polygons rather than contour lines.

C API

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

EXAMPLE

       This  would  create  10meter  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

AUTHORS

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

GDAL                                             Sun Mar 29 2020                                 gdal_contour(1)