5

I have a problem with hillshade function: I've set 315 azimuth, 45 vertical angle and 1 Z factor, but the result is very bad... The original dem file is a .geotiff from Global Data Explorer (Aster Global DEM V2). I would like to obtain a pretty hillshade, but I don't know what is wrong.

Here the original and the screen of the hillshade result. It's 1:660.000 scale

enter image description here

enter image description here

Improve this question
6
  • 1
    I strongly suggest applying a smoothing filter to your DEM before computing the hillshade (no time to write an in-depth answer, sorry).
    – ArMoraer
    Nov 23, 2017 at 10:35
  • 1
    Pixel size of the dem? The problem is not on the tool, just in the low quality of your dem, I think. You can do a smooth on it before or (better) search for a new dem.
    – Sergio
    Nov 23, 2017 at 10:46
  • Welcome to GIS SE! As a new user be sure to take the Tour to learn about our focussed Q&A format.
    – PolyGeo ♦
    Nov 23, 2017 at 10:48
  • Like Sergio, I suggest you either try to smooth you DEM but that could be painful if you have a lot of tiles, or use better data like SRTM 30 arc/sec available for the world since one or two years. Those are great even though some values are missing in high mountain ranges. You can find them on the EarthExplorer platform after creating a free account. Read this article which a very useful comparison between SRTM 3 and ASTER GDEM v2: digital-geography.com/dem-comparison-srtm-3-vs-aster-gdem-v2 Here the link to EarthExplorer: earthexplorer.usgs.gov
    – BFlat
    Nov 23, 2017 at 10:55
  • Welcome to gis.stackexchange! Please note that a good question on this site is expected to show some degree of research on your part, i.e. what you have tried and - if applicable - code so far. For more info, you can check our faq.
    – underdark ♦
    Nov 23, 2017 at 17:48

1 Answer 1

Reset to default
17

I think you are using Geographic CRS not Projected CRS. Usually this hillshade output is due to you are not using a projected DEM such as UTM projection with a meter unit. You need first to reproject your DEM from geographic to UTM (or any desired projection with meter unit) and use Bilinear or Cubic resampling.

You can see the difference between unprojected hillshade and projected hillshade in the image below :

enter image description here

To reproject the DEM data to UTM projection (as an example), go to Raster → Projections → Warp (Reproject)

enter image description here

  • Select the Input File (DEM File).
  • In the Output File: Give a new name to save the output
  • Source SRS is the spatial reference system of the source DEM. In this example, it is EPSG:4326 (it means WGS 84)
  • Check the Target SRS (the target projection): click on Select and choose UTM with correct zone or any desired projection with a meter unit
  • Resample Method: Select Bilinear or Cubic. Here Cubic is selected.
  • Click OK.
  • Use the projected DEM as an input to create a hillshade
Improve this answer
3
  • Well done, thank you ahmadhanb, I reprojected the raster and the result is very good! I'm going to try to improve the quality, however that was the right solution. Thank you very much also to the others who have answered.
    – dan_dap
    Nov 23, 2017 at 12:55
  • Glad it worked :)
    – ahmadhanb
    Nov 24, 2017 at 3:08
  • Check this also gis.stackexchange.com/questions/95337/… . It describes how to create a hillshade with a raster using lat long data
    – Gerardo Jimenez
    Feb 4, 2020 at 13:24

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.