Unmanned Aerial Systems for High-Resolution Laser Scanning Applications
With the recent advancements in unmanned aerial system (UAS) technology, along with the miniaturization of survey-grade airborne laser scanning systems, capabilities and opportunities for deploying unmanned laser scanning (ULS) systems have increased. Traditional terrestrial laser scanning (TLS) surveys provide high point density (hundreds – thousands of pts/m2) of a focus area, but have limited field-of-view and line-of-sight due to the constrained static nature of the setup. Further, the necessity for multiple scan setups to fully capture complex environments using TLS requires additional field acquisition and post-processing time. While airborne and mobile laser scanning platforms relieve many of these limitations, lower point density (airborne), confined operation pathways (mobile), and higher operational costs become a factor. In addition, both airborne and mobile laser scanning are best optimized for large area and/or corridor mapping, and are in contrast financially inefficient for smaller area collections.
Here we discuss the operational use of a Riegl RiCOPTER with VUX-SYS laser scanner for a variety of projects that required both high point density products (hundreds of pts/m2) comparable to TLS data and a field-of-view comparable to airborne and mobile laser scanning. We outline the training, certification, and fulfillment of regulations required to operate Class II UAS in U.S. airspace by a Federal Government agency, as well as the preparation of a detailed operations protocol to promote safety and adherence to evolving regulations. We will detail systematic data collections at the US Army Corps of Engineers Field Research Facility on North Carolina’s Outer Banks; 200 acres of coastal area including dune grass, surf zone, near shore, and building infrastructure. These flights were part of a systematic UAS-based collection activity to outline performance and limitations of UAS in coastal operations and research. The resulting high-resolution ULS data exceeded 500 pts/m2, acquired during three flights under 20-minutes, respectively. With a low flight altitude (60m), slow ground speed (6 m/s), and wide scanning angle (270o), the system was able to measure target areas from multiple angles, resulting in a point cloud with optimized vegetation penetration and a high return rate from vertical surfaces.