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I have started experimenting creating basic 3D elevation models in QGIS recently. It turned out for me that there are several free sources of DEMs, like USGS's EarthExplorer, CGIAR-CSI's Digital Elevation Database and also EU-DEM from the Copernicus Program.

As far as I could have found out, the best resolutions of these data are the following:

  1. SRTM elevation data from USGS's EarthExplorer site is available in 30 meter resolution - 1 arc second
  2. SRTM elevation data from CGIAR-CSI site is available in 90 meter resolution - 3 arc second
  3. SRTM elevation data from EU-DEM site is available in 25 meter resolution - 1 arc second

Is there any significant difference between these data sources and their accuracy? Especially between USGS EarthExplorer and EU-DEM? I would like to use data of Europe and european cities so when I say difference, I mean the resolution, accuracy or quality and not the geographic coverage.

(Basically, I would like to find out which source is the best choice for a 3D model and I cannot see the difference between the American and the European DEM)

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With regards to your question of the difference betwen SRTM and EU-DEM the ESA quotes:

The EU-DEM is a hybrid product based on SRTM and ASTER GDEM data fused by a weighted averaging approach and it has been generated as a contiguous dataset divided into 1 degree by 1 degree tiles, corresponding to the SRTM naming convention.

As they mention ASTER I and the term "hybrid" I would skip this data set. ASTER had major issues as it is an optical system. I would work with SRTM-1 data as it has exetnesive coverage in terms of quality analysis and the physics and methods behind the data are "defined".

I've written some comparisons for a non-urban area: ASTER vs. SRTM 3 and ALOS vs. SRTM1 I hope this helps somehow!

  • Thank you! Your articles include many interesting facts that I haven't known so thanks for the links as well. :) – Skye Mar 25 '16 at 8:13
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The smaller the measurement unit a resolution is the more detailed your image will be. It represents the area included in a single pixel. This applies to all raster data. The difference between the USGS and EU DEMs would be miniscule since it's a difference of 5 meters (which is why you probably can't tell). I would guess you're probably best using the EU one.

  • Thank you! This was my first tought too, but most of the websites that I looked up suggested USGS's data and I was wondering if there was a problem with EU-DEM because it was hardly mentioned anywhere. @Riccardo and adamczi affirmed my suspicion that something is not perfectly okay with EU-DEM – Skye Mar 25 '16 at 8:22
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According to what @Riccardo posted here, I had similar experience with ASTER. Try to draw a profile line of same terrain using first ASTER DEM and than eg. SRTM. ASTER contains a lot of artifacts in field compared to other sources. That's my own experience and quite a popular one among users. It's fairly ok, but I would be careful with using it for more detailed analyses.

PS Have you tried to search for local DEM data source? Some areas are covered with free data (quite remote, but Svalbard for example - 5m DEM from Norwegian Polar Institute, also didn't UK free their LiDAR data recently?)

  • Thank you! I'll check these local data sources for sure! – Skye Mar 25 '16 at 8:16

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