A friend of mine gave me DEM resolutions of cells 5x5m, but there is something wrong with interpolation. When I try to make a cross-section of the terrain I get a pretty inaccurate cross-section, with weird peaks and valleys. What should I do to get a smoother DEM? These are the extensions: enter image description here

enter image description here

cross-section (There is no waterfall there :-) enter image description here

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    Honestly, looking at the DEM I see no way to fix this aside from generating it again from the original data with a different method. Ask your friend for better data. – Gabriel C. Feb 24 '20 at 20:09
  • You think it is not completed or the DEM is damaged? I think that this DEM is generated with some kind of triangulation – nagib Feb 24 '20 at 20:10
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    It looks like it is a patchwork of different sources. The bottom of the valley seems derived from hypsometric curves while the hills/mountains around look like a TIN. They transition badly where they meet, and the TIN seems full of artifacts or bad sample points. I hope you're not doing hydrology! – Gabriel C. Feb 24 '20 at 20:17
  • Not directly with hydrology, but with geomorphometry :-) – nagib Feb 24 '20 at 20:24

The DEM seems to be the result of a Triangulation based on points and lines (probably ArcGis TIN algorithm). One thing that you can do is correct the value of the wrong cells using the Plugin Serval that allow you to change "manually" the value of any pixel. In the case of your DEM I think that the amount of the wrong pixels is small and you can try this approach. I suggest visualising your DEM with Pseudocolour Singleband that exalts the presence of pixel with different values from the surrounding area and, with the Serval tools, just proceed using the Probing mode tool to extract the value of a near pixel and copy in the wrong pixel with the Drawing mode tool.

  • I think there is a lot work to do. There are many mistakes to manually correct. – nagib Feb 24 '20 at 20:59
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    I can understand. Another possibility could extract the contours, remove the smallest parts of them with the Simplify algorithm and recreate a DEM from the cleaned contours. But I am not sure of the result without doing some attempts with your DEM. – Val P Feb 24 '20 at 21:33

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