Synergy of UAV Aerial Survey Methods and LiDAR Scanning for the Study of Planar Objects of Historical and Cultural Heritage

Abstract

The combination of UAV aerial surveys and LiDAR scanning provides high resolution, accuracy, and data comprehensiveness, which are critical for creating detailed digital models and maps. The aim of the work was to create an orthophotomap and an accurate digital surface model of the research area using a synergy of UAV aerial imagery and airborne LiDAR scanning with laser scanners from two different manufacturers. Aerial surveying with UAVs and aerial LiDAR scanning using two scanners, DJI Zenmuse L2 and CHCNAV Alpha Air 450, was conducted for the territory of the historical and cultural reserve "Ancient Zvenyhorod" in Ukraine, which was chosen as the research object. Based on UAV aerial survey data, an orthophotomap of the study area was created at a scale of 1:2000. Additionally, point clouds of the reserve's surface were generated from the aerial survey data and compared with point clouds obtained from LiDAR scanning. It was determined that, since the object's territory covers 26.8 hectares, the aerial survey was conducted from a height of 145 meters in one flight, while the laser scanning of the territory was carried out at a height of 60 meters to better capture the elements of the area. The scanning operations were automatically divided into two scans with UAV landings for battery replacement. The object's territory located at the junctions of the automatically divided scans lacked point cloud information for both scanners. It was proposed to supplement the LiDAR scanning point cloud with points generated from the aerial survey in the area where they were missing. Before copying the point cloud for the area lacking LiDAR data, an analysis and height alignment of points between the LiDAR data and aerial survey were performed. As a result of the research, an accurate digital surface model of the historical and cultural reserve was constructed, containing all elements of its territory.