Airborne Full-Waveform Lidar Swath Mapping of Surface Topography and Vegetation

The 2017–2027 National Academies Earth Science Decadal Survey identified Surface Topography and Vegetation (STV) as a targeted observable, calling for high-resolution, global measurements to improve understanding of the evolution of Earth’s landscape. The Concurrent Artificially-intelligent Spectrometry and Adaptive Lidar System (CASALS) is a novel airborne swath-mapping altimetry lidar that employs a novel transmitter and grating method in combination with a state-of-the-art, high-speed, photon-sensitive detector array. CASALS is designed to exceed current lidar capabilities by providing 3D swath mapping of Earth surface heights and vegetation waveforms with fine cross-track spatial resolution that are especially useful for characterizing the structure of forests.

The current airborne CASALS instrument flew onboard the NASA B-200 King Air aircraft at a typical cruise altitude of 4.5 km for 4 flights completed from 07-18 November 2024 targeting vegetated surfaces and forests over Virginia and North Carolina. The full-waveform lidar collected a total of 256 individual waveforms with ~21 cm horizontal resolution, creating a swath of 55 m across the aircraft flight line during these flights. This work focuses on describing the CASALS algorithm development to identify ground and vegetation features within CASALS waveform data, with a goal of demonstrating progress toward full waveform–to–3D point cloud generation and applicability to a future spaceborne NASA STV mission.