That question motivated me to write this post so as to help
other persons/groups out there who might be stuck in this issue like my good
friend.
Here are the steps for generating a DEM (Digital Elevation
Model) from CONTOURS using GRASS Plugin in QGIS.
To start, ensure you have the GRASS plugin installed in your
QGIS (Plugins > Manage and Install plugins >GRASS)
Load the “Contours”
vector layer in QGIS.
Go to GRASS under the Plugins Menu
Select “New Mapset”.On the Grass Database window,select the
folder in which your project will be stored and Click “Next”
On the Grass location, select “Create new location” and give
it a name and click “Next”.
On the “Mapset” window give a name to the Mapset you are
about to create and click Next
After this, the “Create Mapset window ” should display
showing all the settings we’ve made.Click Finish.
A red Rectangle should be drawn on the QGIS canvas surrounding
the extents in use.
Next
We need to add a Vector layer into the GRASS Mapset
Go to Grass > Open Grass Tools
The window below appears.In the “Module List” search for
v.in.ogr.qgis (To import the loaded vector layer into GRASS) and click on
it.
In the module “Options” tab select the “contours” layer,Name
for the output map and also the name for the new location and click “RUN”.
The progress is shown in the “output” tab.Click on the “View
Output ” button to view the layer in GQIS canvas.
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| Results of first module |
Still on the “Grass Tools” Window, on the “”Module List” tab
search for v.to.rast.attr (We need to convert the vector layer into Raster) and
click to launch.
 |
| Second module |
 |
| Setting parameters |
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| Results of second module |
Now that we have the raster layer, we can now generate our
DEM.
On the Module List, search the r.surf.contour (to generate
DEM from the rasterized contour layer).Enter the name for the output and click ‘Run’
then ‘View output’ and Close.
 |
| Progress in Generating DEM |
The end results should be a DEM
 |
| DEM created |
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| Raster Contours layer overlay on DEM |