The images are beautiful and intriguing, owing to the ability of LIDAR to penetrate vegetation layers to reach surface levels often unseen with traditional methods. The beautiful imagery in the article is from the Washington Geological Survey site ‘The Bare Earth’ which is a descriptive resource on “How lidar in Washington State exposes geology and natural hazards”.
While useful for many types of analysis, this is particularly important to identification of landscape hazards, which had devastating impacts in 2014 in Oso, a town north of Seattle, and you can see some of the images highlighting landslide activity in the region.
The most intriguing image to me was the Mima Mound Natural Area Preserve, which I hadn’t known about before reading this, which look much like a magnification of dermis instead of earth.
The landscape itself is subtly rolling like an earthworks art project, and the reasons for their form is up for debate, as seen in the caption above. The landscape itself is subtle and beautiful, definitely motivated to take a trip down to Olympia.
The pages on the great context on how LIDAR works with a story map of some visuals along with descriptive illustrations. Per the WGS site,
“Lidar (light detection and ranging) is a technology that uses light pulses to collect three-dimensional information. Lidar data is often collected from an airplane using a laser system pointed at the ground. The system measures the amount of time it takes for the laser light pulses to reach the ground and return. Billions of these rapidly-collected measurements (points) can create extremely detailed three-dimensional models of the Earth’s surface. See the diagram below to better understand how airborne lidar is collected.”
A breakdown of the different maps that be extracted from the process.
The beauty of LIDAR is the ability to give an alternative view that is impossible to capture in other ways, particularly in deeply vegetated sites, with lots of coniferous vegetation. Again, from The Bare Earth site: “In geology, lidar bare-earth models allow closer study of geomorphology, which is the study of the origin of the topography of the earth. Landslides, faults, floods, glaciers, and erosion leave their mark on the landscape, and while these marks can be hidden by dense vegetation, they can’t hide from lidar.”
Harkening back to the previous posts of the geology of Seattle, the glacial retreat was a major factor in the Seattle-area geology and current hydrology. The image below shows an aerial image, which reveals little of this feature, but the Lidar image shows the directional scarring and drumlin deposition around Hood Canal in sharp relief.
A video as well elaborates on the technique:
Check out more of Betsy Mason and Greg Miller at All Over the Map and follow them on Twitter @mapdragons
Header image, like many of the other images in the post, is from Washington Geological Survey, via National Geographic,. The header shows “The floodplain and dry, former channels of the Chehalis River in western Washington State are revealed by this LIDAR-based elevation map.”