Digital Geography

24. September 2014

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 means we have to wait =(

Update: Kindly our user Felix Henselowsky asked the USGS for the exact release dates. Here they are:

  • November 2014: Mexico, South America
  • January 2015: Australia, Southeast Asia
  • April 2015: North America, Europe
  • July 2015: China, Japan
  • September 2015: Northeast Africa

 

Earthexplorer


 

Background information about SRTM:

SRTM-datasets (Shuttle Radar Topographic Mission) are activ remote sensing data, obtained during an eleven days long Shuttle flight of Space Shuttle Endevour driven by NASA, DLR and others. The exact mission date was 02/11 to 22/02/20000. During this time the Shuttle had a flying attitude of 233km, sending 1700microwave impulses per second. The signals were reflected by earths surface and detected as radar echos.

 

SRTM Shuttle


 

Due to a C- and X-band interferometry radarsystem two shifted imagery of the earth surface were compared using a “repeat-pass-interferometry-process” concerning elevation and relief. In comparison to other systems the imagery was produced at the same time by using an 60m displaced antenna (see image above). By analysing the interferograms Digital Elevation Modells can be created. A great advantage of such an active remote sensing system is the collection of data without depency on weaher or illumination (Schmidt 2011).

 

SRTM Principle


 

Source: NASA, SCHMIDT (2011): Implikation der Waldkonversion für das geomorphologische Prozessgefüge – eine GIS-gestützte Analyse der räumlichen Verbreitung von Bodenerosion in Mato Grosso (Brasilien), Hamburg (unpublished).

Update: I would like to use this article to add an innovative download-tool for quick SRTM-tile download. It’s much quicker than using EarthExplorer. Just check this Article.