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I heard some time ago about a new global DEM called NASADEM that was going to be released in 2017, and promised to be the best global DEM to date. What exactly is NASADEM and when will it be available?

  • If this is open data then the place to ask this may be the Open Data Stack Exchange (or NASA direct, if that is its source). – PolyGeo Jan 6 '18 at 20:17
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    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 Jan 6 '18 at 21:26
  • Sorry about that underdark, should I edit the question now? – Pedro Jan 6 '18 at 21:59
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NASADEM is a full reprocessing of the SRTM data using state-of-the-art interferometric processing techniques. It also improves accuracy, reduce gaps and improve the quality of the data used to fill gaps (using GDEM v3). More details are described here.

The final version is not ready yet, but a provisional version has been released (not officially) and can be downloaded here: https://e4ftl01.cr.usgs.gov/provisional/MEaSUREs/NASADEM/

In your area of interest look for the "hgt_srtmOnly_R4" folder for the SRTM only data (i.e., not void filled) and in the "hgt_merge_I2" folder for the void filled data. Note that the former contains ellipsoidal elevations and the later geoidal ones.

This provisional NASADEM does have clear improvements over SRTM v3, but I would still recommend to wait for the final version, as there are still many issues. GDEM v3 dataset has not been released yet to the public, but it is already available to NASA, as stated here. By looking at the data, it is clear to me that it was indeed used in the void-filled version of this provisional dataset.

The tiles downloaded from that server above don't have all the ancillary/header information to be loaded in most GIS software, but David Shean wrote some scripts both for bulk download and to generate the header files, those are available in github: https://github.com/dshean/nasadem

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    I did a test comparison of the provisional NASADEM data linked here versus the existing sources in areas that were problematic in previous SRTM data, and while there certainly are some improvements, it also comes with some new issues, likely stemming from the source of the void fills. outerra.blogspot.com/2018/01/… – camenomizoratojoakizunewake Mar 1 '18 at 16:28
  • @camenomizoratojoakizunewake I totally agree with you and I found the same in my area of interest, that is also very challenging for DEM generation. Nice comparison in your link. I''ll add it to the answer. – Camilo Rada Mar 1 '18 at 23:59
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NASADEM, a full reprocessing of the SRTM data (Merged DEM Global 1 arc second) has now been released (as of 13 Feb 2020):

Press release:

https://lpdaac.usgs.gov/news/release-nasadem-data-products/

Tool to import the new NASADEM into GRASS GIS, selectable by bounding box:

https://grass.osgeo.org/grass7/manuals/addons/r.in.nasadem.html

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This link contains our analysis of NASADEM vs SRTM across North America. We used 252 million extremely accurate IceSat-2 terrain height benchmarks for the comparison. The analysis also includes AW3D30 and ASTER DEMs for good measure.

This link is our second analysis of NASADEM across Australia and New Zealand.

NASA also publishes an ellipsoidal height dataset which improves accuracy a wee bit, which can be helpful if you're using bicubic interpolation. It has voids which are easy to correct. Note: its heights are not relative to sea level, and are different than what Google Earth and most other mapping products provide.

In short, NASADEM is a little better than SRTM in forests (less bias), short vegetation, wetland and urban areas, and a bit worse in barren areas and open water. NASADEM is even better in Australia, too. Also take a look at AW3D30 v3.1.

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    If you are linking to your own web site, please be sure to mention that. Please review the promotion policy. – tripleee Jul 29 at 4:44
  • Look like the links to your Analysis need to be updated. I don't see the analysis at the current links. – Brian Swift yesterday

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