The Coastal Processes Group uses LiDAR scanners mounted on trucks, drones, all-terrain-vehicles, buildings, and towers to measure waves, and beach and cliff erosion. LiDAR (Light Detection and Ranging) measures the travel time for a laser photon (traveling at the speed of light) to reflect from a target and return to the source. A concept similar to sonar and radar, but with light instead of sound and radio waves. LiDAR is widely used in construction, agriculture, resource management, and transportation. LiDAR technology is evolving rapidly, with simple versions available on iPhones. We are evaluating LiDARs manufactured by Riegl, Velodyne and Ouster.
Drone mounted mobile LiDAR
We mount a lightweight, short-range (~100m) LiDAR on a drone, and a heavier, more accurate, longer-range (~500m) LiDAR or a truck or fixed tower. Both LiDARs have small (few cm) errors. Mobile LiDARs are integrated with special GPS and IMU hardware. In a few hours the truck-mounted LiDAR scans ~10 km of beach and cliff with high spatial resolution (~1000 pts/m2). Drones provide surveys of otherwise inaccessible cliff tops. LiDAR is also used to measure wave runup.
Truck mounted LiDAR
LiDAR was used to measure the water surface and waves in the surf zone on a cross-shore transect at Torrey Pines State Beach, California. Shown above is a profile view of LiDAR returns from the mobile truck (blue) and hovering drone (red), as waves approach from deeper water on the left to the beach on the right (non-moving points). P01-P06 are locations of buried pressure sensors. LiDAR allows for continuous observations across the surfzone. Scientists can now see the shape and height of waves from the moment they break to dissipation on the beach face.
Tower-mounted LiDAR at Cardiff, California was use to measure runup on the beach below.
Eight minutes of LiDAR observations of wave runup at Agate Beach, Oregon (29 September 2012).