The Giga Revolution in Geomorphometry: Gigabytes of RAM, Gigabyte-Sized Data Sets, and Gigabit Internet Access

TitleThe Giga Revolution in Geomorphometry: Gigabytes of RAM, Gigabyte-Sized Data Sets, and Gigabit Internet Access
Publication TypeConference Paper
Year of Publication2013
AuthorsGuth, P.
Refereed DesignationRefereed
Conference NameGeomorphometry 2013
Date Published2013
Conference LocationNanjing, China
Abstract

Recent advances in computer technology have begun a revolution in geomorphometry. Desktop computers and 64 bit operating systems can access massive data sets like the entire Shuttle Radar Topography Mission digital elevation model from random access memory. Multi-temporal lidar topography, with 1 m or 0.5 m grid spacing, can require gigabytes of data for relatively small project areas, but repeated surveys allow monitoring geomorphometric changes over time. As gigabit internet access reaches greater audiences, the need to download data before beginning analysis might be replaced with just-in-time delivery over the internet. Traditional DEMs like SRTM could be viewed as almost all signal—they might be smoothed or filtered, but there was no way to remove whatever vegetation noise was present, and the user basically had to accept the dataset. With lidar the user can process the point cloud to remove vegetation, and can consider further removing boulders and similar features to get a generalized and more representative view of the landscapes. Views of desert dune landscapes at three scales (1 km—100 m—1m) illustrate these changes. The half gigabyte global data set ETOPO1 easily loads into RAM. The largest dune fields appear at this scale, but few characteristics of the dunes appear and some suffer from aliasing. The SRTM and ASTER GDEM have very similar 100 m real point spacing, and allow automated extraction of dune heights, spacing, and orientation for most dunes, although smaller dunes like many of those in Australia are at the limits for these elevations models. SRTM’s collection over a short period captured a virtually instantaneous snapshot, whereas the ASTER GDEM’s long temporal averaging smears out dune changes. The smallest dunes, such as those at White Sands, New Mexico, only appear well defined in lidar grids with 1 m resolution which can track dune migration.

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