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Is it possible to make a DEM from contours in QGIS? I have a shp file (contours) and their heights, can I use QGIS for produce a DEM without using GRASS? I find this creating a dem from contours but the answer is for Arcgis.

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Have you checked out the link to ANUDEM provided in the reply to the question you reference? That (and certain constrained triangulation techniques: check out r.surf.contour in GRASS) are the only games in town. (The ArcGIS solution is a wrapper around the ANUDEM technology.) –  whuber Dec 21 '11 at 17:56
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Thank you for your useful information. Reading never stops.... But I prefer something for Qgis. –  Vassilis Dec 23 '11 at 10:55
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You should also consider quality - not all interpolation algorithms return useful output for contour lines. There are dedicated methods for this, which are for example provided via the GRASS GIS plugin. –  markusN Dec 26 '11 at 20:58

5 Answers 5

up vote 7 down vote accepted

Yes, there are several options available in QGIS:

  1. Inverse Distance Weighting (IDW) Interpolation plugin - see this for a tutorial
  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.
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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

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.

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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

Check also this paper. I'm writing a qgis module to do that. I hope that it will be available in the next few months.

http://www.sciencedirect.com/science/article/pii/S0924271602000448

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Try Kosmo or GvSIG they have Sextante which has some rasterization tools and interpolation, I have created a tutorial for creating a DEM from contours, it's in spanish but you can easily follow it up. You can find Kosmo here ang GvSIG here.

Hope this helps

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The question was about QGIS. –  Giovanni Manghi Dec 22 '11 at 12:02

Other options you have are With PCI Geomatica.

Check the below link, if it is usefull to you.

"ieeexplore.ieee.org/iel5/10226/32595/01526261.pdf"

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I was curious about the downvote (and planned to upvote this, in the spirit of a comment I posted to an earlier reply), so I went to check the link. Too bad: it goes to a gated site and most people won't get in. Without a detailed explanation, your reply won't be helpful. –  whuber Dec 29 '11 at 5:20

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