SRTM data and Google Earth

I’ve written about this in the past, but thought it was time to revisit the topic.

SRTM = Shuttle Radar Topography Mission, it’s what drives the topo behind Google Earth.

On February 11, 2000, the Shuttle Radar Topography Mission payload onboard Space Shuttle Endeavour launched into space. Leica made the EDM, Daimler Crysler Aerospace made the radars. With its radars sweeping most of the Earth’s surfaces, SRTM acquired enough data during its ten days of operation to obtain the most complete near-global high-resolution database of the Earth’s topography. A 10 day mission almost 9 years ago. How often is the data updated? It’s not… for the most part. While the data may be more accurate than the standard DEM derived from a USGS QUAD, it’s simply not practical for design use. The project was aiming to maintain an accuracy of 16 meters vertically.

Keep in mind, the SRTM project had no ground control. Up and over every building, every highway, every house, every tree. Several algorithms were used to interpolate data in void areas (as well as other areas), but make no mistake, the areas were interpolated.

Google Earth offers us an incredible resource for downloading topo data, but be advised, while the availability of the data is significant for many reasons, the data has been massaged, interpolated, massaged again, and algorithmed to death.

Feeling rather geeky? Check out this article by Frank Clowes of Penn State University (Update – July 25, 2009: This article is no longer available). At the bottom of the page, you’ll also find a link to an SRTM kmz file for use in Google Earth that will give you direct access to the SRTM data. Keep in mind the formatting is a recognized USGS format.

To download Google Earth, click here.

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