Digital Geography

SRTM-1 (1 Arc second) now available with large global coverage

With this post I would like to come back on a topic from September 2014. In this blog post on Digital-Geography I announced that from September 2014 until September 2015 high-resultion SRTM-data will be provided for free by the USGS. We also announced the estimated release dates for certain regions around the globe.     After checking the progress of the release in EarthExplorer, I realized that the release is proceeding much faster than expected. Till this day, only Norhteast Africa is missing. Parts of Canada, Russia, Greenland, Scandinavia, Artica and Antarctica are missing due to the SRTM coverage limit of…

DEM comparison: SRTM 3 vs. ASTER GDEM v2

Let’s get ready to rumble! No, just kidding. We are all excited about the recent message from the white house: SRTM “1” (1 equals 1 arcsecond, whereas 3 was indicating the 3 arcsecond a.k.a. 90m DEM) or the official title SRTM-2 will be available for free in the next months (orig. here, dg here). So why is it so important? Most DEM-interested people will answer: “Use the ASTER DEM if you need 30m!”. But let us have a closer look on both systems and how they perform.