## 2 Materials and Methods
### UAS and Sensors Combination  
To test the various data collection parameters and gather image datasets for each planned disturbance, a multi-rotor UAS was equipped with a mirrorless interchangeable lens (MIL) digital camera and a post-processing kinematic (PPK) sensor (Figure 4, Tables 3 and 4). The UAS used was a DJI Matrice 600 Pro (M600). The platform was selected for its well-balanced combination of payload capacity, rapid deployment, and endurance. With six propeller motors affixed to a full carbon frame, this UAS was powered by six lithium polymer (LiPo) batteries and capable of a relatively long flight time (Max. ~26 min) while remaining steady in strong winds (up to 20 mph) [45]. The UAS and sensor combination was able to rapidly gather multiple datasets, sometimes up to three flights in one day, with precise and accurately geolocated images in a variety of field settings. This allowed for the efficient testing of multiple data collection parameters between flights until quality imagery was consistent. Because the sites were relatively discrete and high temporal datasets were necessary, a multi-rotor was chosen over a fixed wing, which often requires more time in the field and larger deployment areas to be safe and worthwhile [13]. Furthermore, the vertical take-off and landing (VTOL) capability of the multi-rotor allowed the aircraft to launch and land in tight areas, such as road ditches, easement corridors, or small canopy openings, in addition to open areas [48]--all of which were present in this study. Additionally, the M600 was lightweight and had ample surface area that allowed for mounting external payloads, such as the camera and georeferencing system used to capture and geolocate imagery. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Property** & **\# of Trees Harvested** & \begin{tabular}{c} **Amount Harvested** \\ **(in Board Feed)** \\ \end{tabular} & **Harvest Duration** & **UAS Survey Dates** \\ \hline \begin{tabular}{c} Deardorff \\ (17.3 acres) \\ \end{tabular} & 127 & 35,824\({}^{\prime}\) & 5/8/20–5/13/20 & \begin{tabular}{c} Pre-cut. 5/7/20 \\ Mid-cut. 5/18/20 \\ Post-cut. 7/2/20, 10/9/20 \\ \end{tabular} \\ \begin{tabular}{c} Jackson \\ (23.6 acres) \\ \end{tabular} & 126 & 58,702\({}^{\prime}\) & 6/11/20-8/20/20 & \begin{tabular}{c} Pre-cut. 5/16/20 \\ \end{tabular} \\ \begin{tabular}{c} McAfee \\ (27 acres) \\ \end{tabular} & 217 selected* & *Not yet harvested & NA & \begin{tabular}{c} Pre-cut. 5/16/20 \\ \end{tabular} \\ \begin{tabular}{c} Rough \\ (20.7 acres) \\ \end{tabular} & 199 & 11,268\({}^{\prime}\) & 6/1/20-6/10/21 & \begin{tabular}{c} Pre-cut. 5/18/20, 10/9/20 \\ \end{tabular} \\ \begin{tabular}{c} Utron \\ (51.9 acres) \\ \end{tabular} & 311 & 109,209\({}^{\prime}\) & 5/30/20-6/20/20 & \begin{tabular}{c} Pre-cut. 5/22/20 \\ \end{tabular} \\ \begin{tabular}{c} Whiteman \\ (56.2 acres) \\ \end{tabular} & 166 & 74,956\({}^{\prime}\) & 5/13/20-6/25/20 & \begin{tabular}{c} Mid-cut. 5/16/20 \\ Post-cut. 7/9/20 \\ \end{tabular} \\ \
\begin{tabular}{c} Volz \\ (10 acres) \\ \end{tabular} & 65 & 39,515\({}^{\prime}\) & 5/7/20-6/25/20 &
\begin{tabular}{c} Pre-cut. 5/7/20 \\ Mid-cut. 5/21/20 \\ Post-cut. 7/2/20, 8/26/20 \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Selective timber harvest information for each forest site surveyed. “#”—Number. The camera used in this study was chosen because of its interchangeable lens, which was able to fit a short (21 mm) lens with a wide field of view (91.2\({}^{\circ}\)) and had a 24.3-megapixel (MP) resolution. This allowed the camera to capture many overlapping pixels between images, thus providing the photogrammetric software with many tie-points when producing orthomosaic composites [36; 50]. Additionally, the camera was able to capture intense detail (2.3 cm/pixel GSD) while suspended from a moving platform with a frequently changing depth of field. The resolution and wide field of view of this camera are important because, according to [PERSON] et al.