Dear Enrico Giuseppe Cadau

its good but taking into acount that it a Digital Surface Model (DSM) which represents the surface of the Earth including buildings, infrastructure and vegetation

Karim Omar Did have the chance to check differences wrt other local national DEM?

Had no idea this was available. I have some pretty nice data to compare with. I will try and get back to you.

In terms of defining the free DTMs, I think my ranking would be: Aster GDM, Copernicus and SRTM

André Texugo thanks, do you have any results to share?

Hi Enrico Giuseppe Cadau

Check this out:

Article Evaluating the Quality and Accuracy of TanDEM-X Digital Elev...

I am having trouble getting access to the data. Any tips for that?

Rafael Anleu it's easy. Are you register in this plataform?

https://land.copernicus.eu/@@register

I made it to the European Data but I was interested in data for Qatar, any tips here?

Rafael Anleu DEM data wolrdwide at 90m can be freely download:

https://spacedata.copernicus.eu/web/cscda/dataset-details?articleId=394198

Soon also at 30m will be available.

Rafael Anleu Try the ASTER GDM or SRTM. Do you know?

Rafael Anleu QATAR Copernicus DEM at 30m or 90m can be also freely accessed through the EO-Browser (https://apps.sentinel-hub.com/eo-browser/).

Here attached just an example. Enjoy!

Well, finally managed to download the data. Here is a teaser for you...in general it looks pretty good...

Rafael Anleu thanks, are these results computed using Copernicus 90m or 30m?

30m

On which area?

It is Qatar about 50 km to the west of Doha. This is a nice data set because I have high quality field survey and being that the area is basically free from buildings and only very scarce vegetation we can assume that the Surface Model is very close to the Terrain Modell.

I have been working with WorldDEM Surface model data there (as you can see from the profiles) and since COP30m is derived from the same data as WorldDEM I expected it to deliver similar results. But if you get into the detail it seems to deviate significantly from it and from the "ground true" data in some locations.

Very interesting Rafael, the differences might due to the resampling to 30m occurred in the COPDEM-30. Do you have a public paper on the comparison you performed? Many thanks

Do you have more information on the resampling method used to go from the 10 m product to the 30 m product? It's difficult to find, and is not in the Product Handbook. Thanks.

Heather Reese , here the explanation provided by the DEM manufacturer:

To obtain a grid spacing of 1.0 resp. 3.0 arc seconds for Copernicus DEM instances GLO-30 and GLO-90, a weighted aggregation approach is used to determine the new height values as well as height error mask values. The weighted mean of the underlying higher resolution pixels are used. Partly contributing pixels are considered proportionally. Equivalent to the DEM, the reduced layers of the HEM (1 and 3 arc seconds) are also generated through weighted aggregation. All available 8 Bit data (EDM, FLM, WBM) are resampled by applying a majority value approach taking into account the consistent coding of thematic classes throughout all 8 Bit data. For the DTED versions of the Copernicus DEM GLO-30 and GLO-90, the resampling process matches to the resampling of the DGED versions, i.e. weighted aggregation, but with an additional rounding process to achieve integer height information.

Hope this helps.

Hi Heather Reese,

We have taken a close look at the quality and found the Copernicus 30 m to preform very well in comparison to SRTM, ASTER, etc. This Copernicus DEM is essentially an edited and resampled version of the TanDEM-X -- the quality of both is extremely similar, though Copernicus shows a slight improvement. Check out our work here, where there is detailed information on DEM processing, resampling, and links to the most up-to-date product handbooks in the references: https://www.frontiersin.org/articles/10.3389/feart.2021.758606/full

Best,

Ben

Hello, I can only confirm what Benjamin Purinton said. As the Copernicus DEM is an edited version of TanDEM-X it shows improvements in problematic areas such as steep ridges or canyons. We recently assessed the quality of TanDEM-X and Copernicus DEM in mountains and found improvement in RMSE from 45 m to 12 m, from 16 m to 6 m, and from 24 m to 9 m for the Alps, the Pyrenees, and the Carpathians, respectively. You can find more in our recent study: https://doi.org/10.3390/rs13193931