Remotely sensed topography
Learning Goals
- Know what SRTM is, and that it revolutionized our knowledge of Earth’s topography when it was flow on the Space Shuttle Endeavor in 2000.
- Understand how LiDAR works, know what it is, and learn how it gives us information about Earth’s surface and topography.
Shuttle Radar Topography Mission (SRTM)
Even though this video looks like it was cut by a 16-year-old, it is the most informative that I could find available on the Internet! (I watched the whole thing, and it’s good.) Learn about how the first near-global topographic data set was created. Locally, these data are superceded by newer and higher-resolution data sets, but SRTM remains a benchmark against which all of these others are compared, and a active and pervasively used data product.
Light Distance and Ranging (LiDAR)
Laser scans, primarily from airborne platforms (as described in the video from the National Ecological Observatory Network, NEON) is the best way to create high-resolution (~1 m horizontal grid spacing) maps of the land surface. Pardon the 3rd-grade humor in the video: its description of the technology and its applications is very accurate.
Part of this video is about visualizing vegetation with multiple laser returns. Geomorphologists most often use the last return, which is the ground-surface return. If ground-cover vegetation is too thick, this return might be above the actual land surface. But most commonly, true ground returns are obtained, and (if the climate is favorable) many LiDAR flights are taken after leaves are down (but before snow is on) to obtain the best-possible set of ground returns.
Places to download airborne LiDAR data include:
- OpenTopography, which hosts an incredible wealth of research-quality LiDAR data. Their interactive map download portal shows all hosted data sets.
- MnTopo, the state of Minnesota’s airborne LiDAR topography visualization and download center
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