Digital Geography

GDEM V3 vs SRTM 1: a comparison

Some time has past since I last wrote a DEM comparison, comparing ALOS World with SRTM 1 and GDEM V2 with SRTM 3. But as NASA and METI released the lates version of the ASTER GDEM dataset, I will compare this once again for a certain area in central Mongolia. But this time, the competitor will be SRTM 1.

ALOS World 3D V1.1 vs. SRTM1

Some days ago a new version of the ALOS 30m DEM was released: Void pixels due to clouds and snow pixels within 60 deg. of north and south latitudes in Version 1 were complemented by existing DEMs. Out of the areas are same with Version 1 product. As we already compared ALOS with SRTM-1(I saw the ALOS DEM as “the winner”) I am now interested in how this performs in a another setting. We are changing our focus from Mongolia to Germany and check how the new ALOS DEM works compared with SRTM 1.

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.

Announcement: Realease of worldwide high-resultion SRTM-data (30m)

The White House announced on September 23th during the United Nations Heads of State Climate Summit in New York that they are going to release the high-resolution images of SRTM globally. Until now, the high-resolution imagery were only available for US-areas. All other countries had lower resolution imagery. Due to this release the 30m x 30m imagery will be available globally and substitute the 90m x 90m data. After its release the data will be accessible on EarthExplorer by the US Geological Service (USGS). Unfortunately they didn’t announce an exact release date (only “will be released globally over the next year”). That…

short announce: Reverb @NASA the new WIST

Sorry to talk about this important tool with a little delay. As I was lecturing at the university I was using the Warehouse Inventory Search Tool (WIST) by NASA to collect my raster data and download them. It was a great tool but looked a little old. The biggest difference to services like or the SRTM Tile Grabber is, that most data was ordered and delivered by FTP. It was not a big deal as most data was available for free but I think for a lot of users this was not “convenient” enough… Nevertheless Reverb- the new WIST-…

Innovative SRTM Download

It’s been a couple weeks since I’ve posted here, but I just found something I wanted to pass along. If you work with geospatial data, you are probably familiar with the Shuttle Radar Topography Mission (SRTM) that collected elevation data over much of Earth. These data are available from a number of interfaces on the Web, but this is one of the nicest, and most innovative, ones I’ve found. SRTM Tile Grabber Just find the spot on Earth you are interested in and you can download the SRTM data for that area as a geotiff. I think this is probably…