10 Sources to Download Free DEM – Digital Elevation Model
We live in a 3D World and us cartographers, in most circumstances, need accurate and reliable Digital Elevation and/or Surface Models. Some may possess their own airplane, thus being capable of producing their own DEMs, while the vast majority certainly need to know how to derive such data from various credible sources.
We searched and assessed some of the most popular and credible DEM sources, available free on the web, which we exhibit at the following paragraphs.
The word ASTER is actually an abbreviation and stands for Advanced Spaceborne Thermal Emission and Reflection Radiometer. ASTER is a cooperative effort between NASA, Japan’s Ministry of Economy, Trade and Industry (METI), and Japan Space Systems (J-spacesystems). ASTER is a Digital Elevation Model (DEM) and it is used to create detailed maps of land surface temperature, reflectance, and elevation, as you may see at their official website .
You may read all the details about the applied technology behind ASTER or how they created this beautiful DEM at their detailed web page https://asterweb.jpl.nasa.gov/gdem.asp .
In April 2016 all ASTER data products became available at no charge to all users, thus any scene and all derived products can be ordered by anyone. There exist certain ways to get ASTER data, which are listed at the correspondent web page https://asterweb.jpl.nasa.gov/data.asp from which you may select the most suitable to you!
We would recommend:
● NASA Reverb https://reverb.echo.nasa.gov/reverb/
● Earth Explorer https://earthexplorer.usgs.gov/
● Global Data Explorer https://gdex.cr.usgs.gov/gdex/
With the aid of EarthExplorer, we downloaded the DEM data for the mountainous area of Matterhorn, a famous summit of the Swiss-Italian Alps, loaded it to QGIS and generated some contour lines with 20-meter intervals to see how it is. As you can see ASTER may produce some quite satisfying results (pic 1).
ASTER DEM provides a 90 meters resolution for almost 80% of the Globe, with a resolution of 30 meters in the United States. One stated drawback is that in certain cases it may contain distortions in cloud covered areas.