Did you know? Drones and LiDAR surveying

Drone Photography and LiDAR

The 4MR team used unmanned aerial vehicles (UAVs, also known as “drones”) to conduct data acquisitions at project sites safely and with significant economic efficiencies, such as reductions in the number of field personnel required, and the time required for both data acquisition and review. It is a low-cost, low-environmental-impact solution that optimizes the quality and effectiveness of collected data. To map steep and heavily wooded terrain, the team used UAV-mounted LiDAR1 survey equipment. While the UAV navigates specific pre-programmed trajectories to blanket the surface, the LiDAR scanner penetrates the densest of tree canopy to collect survey-grade data. Traditional ground survey was used to make spot checks of the quality of UAV LiDAR data.

FAA-licensed UAV pilots used drones equipped with digital cameras and LiDAR survey equipment to create detailed, georeferenced aerial photography and high-resolution land topography maps. The LiDAR survey equipment on the drone shown flying over Schenley Park and Oakland (Figure A), gathered high-resolution topographic information that was converted to topographic maps (Figure B), 3D models for design, and interpretive hillshade maps (Figure C).

Figure A: LiDAR drone capturing ground surface elevation data over Schenley Park, looking to the north into Oakland.

Figure B. Example aerial photography and topographic mapping. Note the sharpness of the drone aerial photography compared to the relatively pixelated public domain aerial image at the upper right edge of the image.

Figure C: Interpretive LiDAR hillshade maps. Note brighter surfaces are less steep than darker surfaces, and landslide and trail features are made visible, despite being under the tree canopy.

1From Wikipedia: Lidar (also called LIDAR, LiDAR, and LADAR) is a surveying method that measures distance to a target by illuminating the target with pulsed laser light and measuring the reflected pulses with a sensor. Differences in laser return times and wavelengths can then be used to make digital 3D representations of the target. The name lidar, now used as an acronym of light detection and ranging (sometimes light imaging, detection, and ranging), was originally a portmanteau of light and radar. Lidar sometimes is called laser scanning and 3D scanning, with terrestrial, airborne, and mobile applications.