Tag: DEM

A Look Back at the SRTM

Published on by Jonathan Crowe

Last month NASA Earth Observatory ran a two-part series about the Shuttle Radar Topography Mission, which produced a high-resolution digital elevation model of the Earth based on radar data collected by the shuttle Endeavour in 2000. The first part looks at how Endeavour gathered the data, the second part at how it’s been used.

Nearly a quarter century after the mission to map the world, the SRTM’s data still yields results. Just this year, it aided in wildfire forecasting for Iran’s Zagros Mountains, tracking soil erosion in South Africa, assessing flood risk on the coast of Brazil, and even determining how the locations of power-generating wind turbines affect real estate values. Tens of thousands of research papers are published every year that rely on SRTM maps for these and other environmental, economic, agricultural, and public safety studies.

Better Lunar Mapping Through Semi-Automated Photoclinometry

Published on by Jonathan Crowe

A method to improve the accuracy of maps of the lunar surface was published last month in The Planetary Science Journal. Photoclinometry, also known as shape-from-shading, can dramatically improve the resolution of digital elevation models generated from Lunar Reconnaissance Orbiter data, but it’s apparently rather labour-intensive. From the Brown University press release: “The scholars outline in the study how advanced computer algorithms can be used to automate much of the process and significantly heighten the resolution of the models. The new software gives lunar scientists the tools to create larger maps of the Moon’s surface that contain finer details at a much faster pace, the researchers say.” [Universe Today]

Antarctica at Eight-Metre Resolution

Published on by Jonathan Crowe

The Reference Elevation Model of Antarctica (map poster)

The Reference Elevation Model of Antarctica is a terrain map of nearly the entire continent at eight-metre resolution, assembled from observations from polar-orbiting satellites (mostly in 2015 and 2016). Version 1 covers 98 percent of Antarctica, and observations are ongoing. Notably, each grid point is timestamped, which will allow researchers to track changes over time (useful when your continent is melting). Raw data is available for download, as are map posters; the data is also available via web apps. [Geographical]

ArcticDEM Release Six Adds Eurasia

Published on by Jonathan Crowe

The sixth release of the ArcticDEM initiative adds 32 percent more terrain data, mostly in Russia and Scandinavia. ArcticDEM provides a two-metre-resolution digital elevation model for arctic regions north of the 60th parallel, plus those bits of Alaska, Greenland and the Kamchatka Peninsula south of 60. The final product is due out next year. More at Earth & Space Science News. [GIS and Science]

High-Resolution Elevation Data Released for Alaska

Published on by Jonathan Crowe

The White House
The White House

A new digital elevation model of Alaska was released earlier this month. The result of a presidential directive to improve elevation maps of Alaska as a tool “to help to help communities understand and manage” the risks of climate change, the ArcticDEM project is a collaboration between the National Geospatial-Intelligence Agency (NGA), the National Science Foundation (NSF) and the University of Minnesota, among others. The unclassified data gives two-metre (or better) resolution across the state. Lower-resolution DEMs for the entire Arctic will follow next year.

Digital elevation data for Alaska had previously been poor; the National Geographic article leads with the point that Mars has better topographic maps than Alaska does. Most digital elevation data is collected by airplane—an impractical method in the far north; the ArcticDEM is based on stereo imagery from DigitalGlobe satellites. (As a comparison, the Shuttle Radar Topography Mission’s DEM resolution is 30 metres for the U.S., 90 metres elsewhere.)

ArcticDEM data is available on the ArcticDEM Explorer page and on the NGA’s Arctic Support 2016 page.

After the cut, a comparison of digital elevation models pre- and post-ArcticDEM, using Anchorage, Alaska.

Continue reading “High-Resolution Elevation Data Released for Alaska” →

The First Global Topographic Map of Mercury

Published on by Jonathan Crowe

mercury-topo-robinson-nolabels

The first complete topographic map of Mercury, based on data from the MESSENGER mission, was released last Friday: MESSENGER, USGS. The version above is a Robinson projection without labels (Robinson with labels, global DEM). “Mercury’s surface is colored according the topography of the surface, with regions with higher elevations colored brown, yellow and red, and regions with lower elevations appearing blue and purple.” [GIS and Science, The National Map]