## 4 Experimental Tests
### Verification of Field Applicability Using Port Structure Images  
To verify the applicability of the proposed method, an experimental test with an image of one of the major port structures in the Incheon Republic of Korea was performed. An inspection drone specialized for port facilities was developed containing the following: a module for precise three-dimensional position control using multiple GNSS and corrected  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Experimental Test**} & \multicolumn{4}{c}{**Translation**} & \multicolumn{4}{c}{**Rotation**} \\ \cline{2-11}  & \multicolumn{2}{c}{**w/o GA**} & \multicolumn{2}{c}{**w/ GA**} & \multicolumn{2}{c}{**w/o GA**} & \multicolumn{2}{c}{**w/ GA**} & \multicolumn{2}{c}{**w/ GA**} \\ \hline RMSE of Case 1 & & & & & & & & & & & \\ (\(-10\)mm translational movement along X-axis) & & & & & & & & & & & \\ \hline \multirow{9}{*}{\
\begin{tabular}{c} Errors of experimental results with ten different GA parameters \\ \end{tabular} } & 1-1 & & & 0.4 & \(-\)0.1 & 0.5 & & & & 0.2 & \(-\)0.6 & 0.0 \\  & 1-2 & & & 0.7 & 0.0 & 0.1 & & & & 0.2 & \(-\)0.4 & 0.0 \\  & 1-3 & & & 1.0 & \(-\)0.4 & 0.7 & & & & 0.3 & \(-\)0.2 & 0.0 \\  & 1-4 & & & 0.7 & \(-\)0.4 & 0.4 & & & & 0.3 & \(-\)0.3 & 0.0 \\  & 1-5 & & & & \(-\)0.2 & \(-\)0.2 & 1.0 & & & & 0.3 & \(-\)1.0 & 0.0 \\  & 1-6 & & & 0.9 & \(-\)0.4 & 0.8 & & & & & 0.3 & \(-\)0.4 & 0.0 \\  & 1-7 & & & & 1.1 & \(-\)0.4 & 0.4 & & & & 0.3 & \(-\)0.1 & 0.0 \\  & 1-8 & & & & 1.3 & \(-\)0.5 & 0.4 & & & & 0.4 & 0.0 & \(-\)0.1 \\  & 1-9 & & & & 0.4 & \(-\)0.3 & 0.6 & & & & 0.3 & \(-\)0.5 & 0.0 \\  & 1-10 & & & & 1.1 & \(-\)0.6 & 0.3 & & & & 0.5 & \(-\)0.1 & 0.0 \\ \hline \multicolumn{11}{c}{RMSE of Case 2} & \multicolumn{4}{c}{2.3188} & \multicolumn{4}{c}{2.0538 (\(-11\%\))} & \multicolumn{4}{c}{0.8794} & \multicolumn{4}{c}{0.5255 (\(-40\%\))} \\ (5\({}^{\circ}\) rotational movement about X-axis) & & & & & & & & & & & & \\ \hline \multirow{9}{*}{
\begin{tabular}{c} Errors of experimental results with ten different GA parameters \\ \end{tabular} } & 2-1 & & & 2.8 & 0.0 & \(-\)2.5 & & & & \(-\)0.8 & \(-\)0.7 & 0.0 \\  & 2-2 & & & & 3.1 & \(0.0\) & \(-\)0.1 & & & & \(-\)0.6 & \(-\)0.7 & \(-\)0.1 \\  & 2-3 & & & & 3.1 & \(-\)0.2 & \(-\)1.2 & & & & \(-  
signals, a module for mounting a multi-angle camera and a front gimbal, and a folding frame capable of being carried by a person for photo and videography (see Figure 8a). The Figure 8b shows the 3D flight trajectory when capturing the images at high altitude. Through the development of real-time image streaming control technology that integrates the ground control module and the LTE module, it is possible to control the drone in the invisible area more than 3 km away from Incheon port.  
The artificial movement of the structure was generated by moving the target structure using an integrated orthophoto, and the relative displacement of the structure between two images was calculated as shown in Figure 9. The figure shows that the main displacement is predicted by the \(X\)-axis displacement, which is the longitudinal directions of the target structure. The estimated relative displacement in the test is found to be \(D=[-43,011.9,\)\(-825.5,\)\(439.6,\)\(-1.2,\)\(0,\)\(2.6]\) with all units in mm or degrees. The intrinsic parameters were tuned by using GA with the specifications of the structures, which are the coordinates of feature points in the fixed and the target structures. By using the proposed method, it will be possible to determine whether to continue using the port structures by estimating the displacement before and after a disaster.