## 2 UAV Video Image Collection Program
### UAV Vison-Based Monitoring Plan and Reference Target Layout  
The structural motion of the 6-story mass timber building was captured by monocular cameras on three off-the-shelf commercial UAV platforms in three different views aimed at capturing structural motions in all DoFs. Characteristics of these UAV platforms are summarized in Table 3. The present article focuses on analyzing the plan-view videos, where the DJI Matrice 300 UAV was consistently utilized to capture time-series imagery with a frame rate of 59.94 frames per second (fps). An example camera view of the plan-view videos (the first video frame from MID 15 test video) with a triple zoom-in view for reference targets with various patterns is shown in Figure 2. For all plan-view videos, the UAV was hovering at a position approximately 55 m above the shake table platen (approximately 35 m above the roof of the building specimen) to maintain a similar pixel resolution for all the videos. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**\begin{tabular}{} \end{tabular}**} & \multirow{2}{*}{**\begin{tabular}{} \end{tabular}**} & **\
\begin{tabular}{} \end{tabular}**} & **
\begin{tabular}{} \end{tabular}** \\ \cline{2-5}  & & **X** & **Y** & **X** & **Y** \\ \hline
7 & 67\% MCE\({}_{\text{R}}\) & 0.64 & 0.89 & 13.94 & 22.36 \\
8 & 100\% MCE\({}_{\text{R}}\) & 0.89 & 1.10 & 19.72 & 33.71 \\
12 & 67\% MCE\({}_{\text{R}}\) & 0.74 & 0.83 & 20.84 & 15.99 \\
13 & 67\% MCE\({}_{\text{R}}\) & 0.58 & 0.85 & 9.26 & 17.14 \\
14 & 68.9\% MCE\({}_{\text{R}}\) & 0.77 & 1.07 & 19.05 & 15.99 \\
15 & 100\% MCE\({}_{\text{R}}\) & 0.91 & 1.11 & 29.16 & 24.19 \\
16 & 100\% MCE\({}_{\text{R}}\) & 0.72 & 1.16 & 11.61 & 22.64 \\
17 & 100\% MCE\({}_{\text{R}}\) & 1.01 & 0.99 & 28.16 & 24.46 \\
18 & 110\% MCE\({}_{\text{R}}\) & 0.91 & 1.32 & 24.46 & 36.28 \\ \hline \hline \end{tabular}  
* Peak responses are the peak absolute valued response in X or Y direction (regardless of +/ – in the given direction). 2 Both roof acceleration and displacement responses are absolute (total) values, i.e., including the shake table movement.  
\end{table} 
Table 2: Summary of structural responses of the building for the tests captured by UAV imagery. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Camera View** & **UAV Platform** & \begin{tabular}{} \end{tabular} & \begin{tabular}{} \end{tabular} & \begin{tabular}{} \end{tabular} & \
\begin{tabular}{} \end{tabular} &
\begin{tabular}{} \end{tabular} & **Resolution** \\ \hline Plan view & & & & & \\ (XY view) & DJI Matrice 300 UAV & 810 \(\times\) 670 \(\times\) 430 & 55 & 59.94 & 3840 \(\times\) 2160 \\  & with DJI Zemnuse P1 & & & & \\  & Camera & & & & \\ \hline East view & & & & & \\ (YZ view) & & 322 \(\times\) 242 \(\times\) 84 & 31 & 29.97 & 3840 \(\times\) 2160 \\  & DJI Mavic 2 Pro UAV & & & & \\ \hline North view & & & & & \\ (XZ view) & & 348 \(\times\) 283 \(\times\) 108 & 45 & 29.97 & 3840 \(\times\) 2160 \\  & DJI Mavic 3 Enterprise & & & & \\ \hline \hline \end{tabular}  
* Peak responses are the peak absolute valued response in X or Y direction (regardless of +/ – in the given direction). 2 Both roof acceleration and displacement responses are absolute (total) values, i.e., including the shake table movement.  
\end{table} 
Table 3: Characteristics of UAV platforms used for shake table test imagery [31]. In the UAV vision-based monitoring plan, reference targets were installed on the ground, safety towers, and the building specimen to provide robust image features for detection and tracking. Targets on the ground and safety towers served as stationary features, providing reference points for camera pose recovery and facilitating identification of 3-D world coordinates extracted from the high-resolution point cloud model obtained from photogrammetry (discussed in Section 4). In total, 10 stationary targets (8 on the ground and 2 on the top of safety towers) and 28 moving targets (on the roof panel) were used in the present study.