Forest storm damage monitoring in Järvselja, Estonia with unmanned aerial vehicles

This paper provides an overview of a small research project. The object of the research was a 16 km² forested area located in the territory of Järvselja Study and Experimental Forest, Estonia, which was damaged by storms in June 2021. The aim of the study was to investigate whether it is possible and reasonable to estimate the area of storm damage using orthophotos created from photographs collected from unmanned aircraft. The surveying was carried out on July 13–15, 2021. The data was collected via unmanned aerial vehicles with RGB-cameras on board. A multi-rotor drone DJI Phantom 3 Professional and a fixed-wing unmanned aircraft eBee X were used. In total, the eBee drone was flown 11 times to obtain 11,989 photos and the DJI drone 18 times to obtain 2,471 photos. During the project, it became clear that if there are open fields available, it is more efficient to use a fixed-wing type drone for this kind of research. However, in more difficult conditions where there are no clearances suitable for take-off and landing, a multi-rotor drone, such as the DJI, can be used instead. It can be concluded from the results of the work that although it is possible to use an unmanned aircraft for aerial photography of large forested areas, it takes a considerable amount of time for both photography and post-processing. It took 96 man-hours to collect the data and four working weeks to process the data.