Developing a procedure to produce large-scale topographic maps of open-pit mines using rotary wing unmanned aerial vehicles

Recently, the rapid development of unmanned aerial vehicle (UAV) has led to increasingly popular applications of this technology in the field of surveying and mapping. This article presents the result of developing a procedure to produce large-scale topographic maps for open-pit mines in Vietnam in which unmanned aerial vehicles (UAV) are used to collect data. With the goal of creating a procedure that ensures accuracy, safety, and efficiency for the production of topographic maps, the theories and official regulations for measuring and editing topographic maps in general and in mines in particular, as well as using drones in Vietnam have been applied. The procedure is specifically developed for the vertical takeoff and landing (rotary) UAVs. Experiments consisting of the flight altitude calculation, determining the appropriate take-off position, and image acquisition were conducted at two open-pit mines, namely Dong Da Mai coal mine and Long Son quarry to verify the procedure. The digital surface models (DSM) and orthophotos are generated from the acquired photos, georeferenced to the VN-2000 coordinate system using ground control points (GCP), and evaluated with checkpoints. In addition, the experiment included the investigation of the various combination of GCP networks to determine the optimal GCP number for each case. Experimental results show that the procedure is logical, correct, straightforward, safe, and effective. UAV resulted products, such as orthophotos, DSM, and topographic maps were accurate and met the requirements of all the national standards.