Comparison of Autonomous and Manual UAV Flights in Determining Forest Road Surface Deformations

The deterioration of the surface of forest roads is an important factor affecting the safe navigation of vehicles and traffic safety. In addition to traditional methods, automated methods are also used to determine the deterioration of the road surface. UAV systems, which are among the automated methods, are widely used to determine surface deformations with high accuracy. In this study, it was aimed to evaluate advantages and disadvantages of two different flight modes of UAV, i.e. autonomous flight and manual flight in mapping road surface deformations. Within the scope of this study, Kardüz Forest Management Chief (Düzce / Turkey), 50-meter section of the Type B forest road was selected. In the study, starting from the pros and cons of the autonomous and manual flight data acquisition process, the outputs obtained as a result of photogrammetric processing of the data, has been compared in terms of features such as data size, with precision and accuracy. In addition, the deformation status of the zones created within the road surface was determined in both flight methods by taking advantage of the average Z value differences. As a result of the study, the number of images taken from manual flights was found to be 5.5 times higher than autonomous flights and the flight time was 4 times higher. The average ground sampling distance of the orthophotos produced from flight images provided 7 times higher resolution in manual flights compared to autonomous flights. When manual flights and autonomous flights are evaluated in terms of reducing the shadow effect, manual flights can be considered as more advantageous. Furthermore, it was found that the dynamic mobility of erosion and accumulation on the road surface continued in time series in both flight methods.