Finding Digital Elevation Maps (DEMs)
NASA and Japan’s Ministry of Economy, Trade and Industry (METI) collaborated to create a Global Digital Elevation Model (GDEM) covering 100% of the earth’s land surface between 83 degrees north to 83 degrees south. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) acquires stereoscopic near infrared images with 15 meter horizontal resolution. The 1.5 million scenes were stereo-correlated and processed to remove clouds and correcting anomalies. The data is available in tiles of 1 degree by 1 degree with 30 meter horizontal and 20 meter vertical accuracy. Advanced processing and inclusion of additional images removed more of the residual anomalies to create ASTER GDEM version 2. <http://www.jspacesystems.or.jp/ersdac/GDEM/E/4.html>
We can download digital elevation data for the Earth’s surface. Additionally, a web search can be used to discover the latitude and longitude of the areas of interest. For this example, we will focus on the terrain of the Grand Canyon.
è Web search for “Grand Canyon Wikipedia”
è On the Wikipedia page, find the latitude and longitude coordinates at upper right portion of the page. 36,06N 112,06W
There are 3 different sources for downloading the GDEM ASTER data. The process for each source is explained in the tabs above.
1) NASA Reverb
2) LP DAAC Global Data Explorer (USGS)
3) J-spacesystems in Japan
All three require you to create a free user login. NASA and J-spacesystems allow you to select grid rectangles. The USGS system allows selection of any arbitrary shape of data. The source data is the same for all three.
The libguide “Creating 3-D visualization in ArcMap using Hillshade” tells how to simulate 3-d visualizations in ArcMap using these DEMs.
The Libguide “Creating 3-D maps in ArcGlobe - a Grand Canyon fly through” tells how to create 3-d visualizations and visually fly through the terrain using ArcGlobe and these DEMs.