## 4 Case Study
### Data Analysis and Field Validation  
After performing a 3D laser scan, the raw point cloud data need to be processed. Cyclone was selected as the software to process point cloud data because it is a software developed by Leica, the manufacturer of 3D laser scanner used in the study, hence avoiding compatibility problems in between the software and the equipment and avoiding the cost of purchasing a new software since Cyclone comes with the Leica 3D laser scanner. The project used China Geodetic Coordinate System 2000 (CGCS2000) as its main georeference system. The Lecia Total Station surveyed each control point under the CGCS2000 system. The registration process of combining the 16 scans was under the 5 mm of accuracy. Once the point cloud is registered, the control points were used to georeference the entire data in the CGCS2000 system. The georeferencing accuracy is also within 5 mm. Thus, the BIM model and point cloud data were in the same coordinate system and could be compared. Due to the high density and the noise data from the original point cloud data, it was necessary to eliminate the point cloud noise and use the feature extraction algorithm to reduce the number of point clouds and the reading time of the computer. Noise data caused by material reflection was cleaned manually, and then the \"region grow\" function in the Cyclone was performed to smooth out the surface of the anchor plate. After that, the point cloud data were extracted and saved in IFC format for storage to facilitate comparison with BIM data. Based on the design tolerance provided by the manufacturer, as shown in Figure 16, the offset on the \(X\)-axis (\(\pm\)3 mm), \(Y\)-axis (\(\pm\)5 mm), and \(Z\)-axis (\(\pm\)10 mm) need to be evaluated and measured, as shown in Figure 9. To measure the torsion deviation, each anchor plate was controlled by four check-points, which are the four corners. The errors were calculated manually by comparing the created BIM model and the scanned point cloud data, as shown in Figure 17.  
Researchers examined the distance and the offset of the three axes between the center point of the anchor plate. The required center to center distance is 3000 mm. The actual distance is 3003 mm with \(-\)3 mm on the \(X\)-axis, 3 mm on the \(Y\)-axis, and 2 mm on the \(Z\)-axis. All of them met the quality requirement, as shown in Table 3. Table 4 shows the deviation of the control points to determine the torsion quality. The most significant deviation is 5 mm on the \(Z\)-axis, and it is within the requirement of \(\pm\)10 mm. Figure 15: Scan of the anchor plate: (**a**) Scan anchor plate after pouring concrete and (**b**) anchor plate point cloud after pouring concrete. A final performance test was conducted to check the water leakage along with another structural testing before it was applied to the entire project, as Figure 18 shows [5]. The posts' bending resistance and the seepage resistance of the removable floodwall system met the design requirements. The removable floodwall construction project was completed, as shown in Figure 19. All the quality control tolerance was accepted. Figure 16: Design tolerance. Figure 17: Comparison between BIM and point cloud data. \begin{table}
\begin{tabular}{c c c c c} \hline \multirow{2}{*}{**Anchor Plat**} & \multirow{2}{*}{
\begin{tabular}{c} **Control** \\ **Point** \\ \end{tabular} } & \multicolumn{3}{c}{**Error (mm)**} \\ \cline{3-5}  & & \(\triangle\)**X** & \(\triangle\)**Y** & \(\triangle\)**Z** \\ \hline \multirow{4}{*}{Left} & A & 2 & 1 & 3 \\  & B & 3 & 3 & 5 \\  & C & 2 & 3 & 2 \\  & D & 2 & 3 & 3 \\ \hline \multirow{4}{*}{Right} & E & 2 & 3 & 4 \\  & F & 1 & 2 & 3 \\ \cline{1-1}  & G & 2 & 2 & 2 \\ \cline{1-1}  & H & 3 & 1 & 5 \\ \hline \end{tabular}
\end{table} 
Table 4: Deviation of the control points. Figure 18: Floodwall performance test [5]: (**a**) Floodwall testing site, (**b**) no water, (**c**) with water (at 1.8 m height).