# gdal_contour

builds vector contour lines from a raster elevation model

## SYNOPSIS

    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>

## 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.
-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, default is shapefiles.

-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".

## 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

Generated for GDAL by 1.7.1.