Application and Accuracy of Unmanned Aerial Survey Imagery after Salvage Logging in Different Terrain Conditions

Abstract

The accuracy of the positioning of the data collected by remote sensing platforms is of great importance in forest and wildlife surveys, salvage logging, soil disturbances after felling operations, fire risk management and many other forestry-based research. The significance of bark beetles in silver fir and Norway spruce stands is an essential factor that can affect the increase in biomass quantity and the reduction of its quality. Due to an Ips typographus (L.) outbreaks in the central part of Croatia from 2016 to 2021, salvage logging was performed in an area of 11,940 ha, with terrain slopes varying from 0 to 172.83%. Two plots of similar sizes (<5 ha) and different terrain conditions (flat vs. sloped terrain) were chosen and were measured in June 2022. Measurements included a total station, a real-time kinematic (RTK) GNSS (Global Navigation Satellite System) terrestrial receiver and an unmanned aerial system (UAS) in order to determine the accuracy of a digital terrain model (DEM) generated by a photogrammetric UAS. In total, 175 checkpoints were marked in the field. Four different GCP (Ground Control Point) classes (5, 10, 15 and 20) were used to compare validation points acquired from the original point clouds, imagery and orthophotos to the reference positions. This study showed that, in terms of a forest area recognition after conducted salvage logging, the use of 10 GCPs for terrain evaluation is necessary even in small areas below 5 ha and regardless of terrain slope.

Leveraging Text Mining for Analyzing Students' Preferences in Computer Science and Language Courses

“…In the same way, the development of digital competences makes it essential for students to take on challenges that demonstrate continuous changes with the efficient performance of digital tools [40]. Consequently, ArcGIS was the software choice for Forestry and Environmental Engineering students due to the positioning accuracy of data collected by remote sensing platforms, which is of great importance in forestry and wildlife studies, salvage logging, soil disturbance after logging operations and fire risk management [41]. In health science, Nutrition was the recommended course for Medical Technology and Food Industry Engineering students; for example, nutrition education has a significant impact on material knowledge and child nutritional status [42].…”