View source for DEM to contour lines

== From DEM to vector contour lines ==

The extraction of isolines (in the case of an elevation surface, contours), can be derived from raster data using the module {{cmd|r.contour}}. Bu default, the module determines the minimum and the maximum isoline values for a given raster map. The isoline/contour interval should be provided by the step parameter.

Example: generate contours with a 10m interval from the raster map "elevation" (North Carolina [http://grass.osgeo.org/download/sample-data/ sample dataset]):

<source lang="bash">
# set the computational region
g.region rast=elevation -p

r.contour elevation out=elev_contour_10m step=10

# visualize
d.mon x0
d.erase
d.rast elevation
d.vect elev_contour_10m
d.barscale -mt
</source>

The resulting contour lines are now stored in the vector map "elev_contour_10m".

[[Image:Contour lines from DEM.png|center]]

== See also ==
* [[Contour lines to DEM]]

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