Ideas For Exploiting NASA's SRTM Data

MaxTardiveau writes with an excerpt from an article where the pictures are worth clicking through for: "Ten years ago, in February 2000, NASA mapped the entire world in eleven days. It's true: the mission was called the Shuttle Radar Topography Mission (SRTM), and over the course of eleven days, it used a big radar attached to the space shuttle to get elevation data from the vast majority of solid Earth; practically all land between 60 degrees North and 56 degrees South was included, with a resolution of 30 meters (90 feet). Over 9 terabytes of data were captured. It then took two years to process that data and make it usable (and it is still being refined to this day). This data is freely available to anyone, and the number of possible applications is almost infinite. It's been used in GIS, cartography, environmental planning, weather modeling (weather patterns are enormously influenced by the topography), flight simulators, Google Earth, and the list goes on. In this short article, I would like to give you a quick tour of the kinds of things this data can reveal. My hope is to get you thinking about what else could be done with this incredible resource."

Comments

Raw data

[cellarmation]

The raw data, as well as data from multiple other sources can be downloaded from NASA's Earth Explorer http://edcsns17.cr.usgs.gov/EarthExplorer/. The article doesn't really address the fact that the Google data has been cleaned up a lot. SRTM has a lot of voids and areas of poor quality, especially over mountains. The resolution of the data is worse for anywhere outside of the USA.

Re:Raw data

[cellarmation]

The ASTER data is at a much higher resolution, but it is debatable if it is much better accuracy than SRTM. I think even the wikipedia page mentions this. I think the problem is the two data sources are developed using very different methods (InSAR vs photometric stereo). The error in SRTM is quite obvious, large voids and no signal areas. ASTER suffers from high frequency noise and poor feature matching in complex scenes, these types of errors are not so easy to detect and account for.

Re:Don't you love weasel language

[radtea]

I suspect that the vast majority of the sea is at sea level.

The Earth's gravitational field is not purely radial, resulting in very significant deviations from mean sea level over much of the ocean's surface. I believe the deviations can be up to tens of metres--I may be recalling incorrectly but I think there's a big one in the South Pacific that is something like 60 m deep and is getting on for a thousand kilometres across.