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I have a shapefile with contours and their heights.

Is it possible to make a DEM from contours in QGIS without using GRASS?

I found Creating DEM from contours using ArcGIS Desktop? but the answer is for ArcGIS Desktop.

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Yes, there are several options available in QGIS:

  1. Inverse Distance Weighting (IDW) Interpolation plugin - see this for a tutorial (archived from the original).
  2. GDAL Raster plugin - to access, click Raster > Grid (Interpolation). GDAL's interpolation is more robust because you can use other interpolation algorithms (IDW, nearest neighbor, moving average, etc.). This tools only works for point data.
  3. GRASS GIS Plugin - there are several modules you can use (v.surf.* and r.surf.*). You need convert your shapefile into a GRASS database to use the GRASS modules in QGIS.
  • Are you sure, because when I execute your second suggested procedure, with GDAL Raster, it shows me this error message: "No point geometry found on layer modashp, skipping." – Vassilis Dec 21 '11 at 11:00
  • I updated the answer that it only works for point data. You can also look at GRASS GIS which has plugin in QGIS. – maning Dec 21 '11 at 11:27
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    The QGIS Interpolation plugin works olso with contour lines: add the attribute that holds the value to interpolate then in "type" select "structured lines" or "break lines" – Giovanni Manghi Dec 21 '11 at 12:30
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    IDW is inappropriate for contour line data. When forced to work with them, it will produce awful DEMs (they will look like terraces). Nearest neighbor and moving averages have similar problems. Interpolating rasters from contour lines requires specialized methods. – whuber Dec 21 '11 at 17:54
  • @whuber - any hints on these specialized methods? Seem to be getting OK results with inverse-distance-to-a-power in the Raster|Grid (Interpolation) tool, but definitely not perfect! – Simbamangu Dec 23 '11 at 6:58
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GRASS has also many options

http://grass.osgeo.org/wiki/Contour_lines_to_DEM

available one way or another also trough the QGIS/GRASS plugin.

  • Didn't the question specifically exclude GRASS? (You might want to rethink your comment to the reply by @jdeltoro.) Nevertheless, if a good solution is not available in QGIS, it is wise to cast one's net wider, so it's good to know of alternative solutions. – whuber Dec 23 '11 at 13:48
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    It depends what does mean "without using GRASS". This because many people do not know they can use GRASS tools inside QGIS like any other QGIS tool, without knowing at all what GRASS is or how it works. – Giovanni Manghi Dec 23 '11 at 14:07
  • Yes, for a small tutorial see grass.osgeo.org/wiki/QGIS_GRASS_Cookbook – markusN Dec 28 '11 at 0:50

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