# Automatic Bridge Design Parameter Extraction for Scan-to-BIM
## 5 Conclusions and Future Work  
In this study, we developed a system that automatically extracts design parameters from point cloud data (PCD) of bridges. The overall system consists of three components: (1) noise reduction, (2) 3D transformation, and (3) design parameter extraction. To validate the performance of the developed system, two different validation tests were conducted. The first validation test predicted the design parameters from PCD created based on BIM models. Since the reference design parameters are predetermined, the performance of the proposed system was validated by comparing with the predetermined parameters. As a result, an error rate of 0.06% was shown without noise, and an error rate of 1.95% was shown for 5% of noise + data loss. The proposed method was able to predict the design parameters with reasonable accuracy even when excessive noise + data loss were given. The second validation test was conducted on the Osong test track fifth bridge in Nojang-ri, Jeondong-myeon, Yeongi-gun, Chungcheongnam-do, Korea. As a result of on-site field validation, the error rate of the design parameter extraction system was 0.8%. Four main sources of error were identified and discussed. The extracted design parameters are used for BIM construction through a parametric library. By applying the proposed method, it is expect to reduce the time and cost required to manually obtaining design parameters from the PCD, and thus improve the current process of scan- to-BIM. Currently, the proposed method is limited to girder bridges including beam girder bridge, T-girder bridge, plate girder bridge, steel box girder bridge, and PSC box girder bridge. In the future, we are planning to expand the current work to different types of bridges such as truss bridges, suspension bridges, and cable-stayed bridges. In addition, components (e.g., deck, pier) and the span of the bridge were manually divided from the PCD in the current stage. If the process of dividing the spans can be automated using computer vision and deep learning, the current scan to BIM is expected to be fully automated in the future. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & & & & & & & & & \\ \hline
**Span. No** & \(\mathbf{H}_{1}\) & \(\mathbf{H}_{2}\) & \(\mathbf{L}_{1}\) & \(\mathbf{W}_{1}\) & \(\mathbf{W}_{2}\) & \(\mathbf{W}_{3}\) & \(\mathbf{W}_{4}\) & \(\mathbf{W}_{5}\) & **Avg** \\ \hline
1 & 0.96 & 0.57 & 0.04 & 0.19 & 0.14 & 0.11 & 0.44 & 2.65 & 0.64 \\
2 & 0.50 & 0.51 & 0.15 & 0.17 & 0.16 & 0.11 & 0.90 & 1.49 & 0.50 \\
3 & 0.83 & 1.66 & 0.04 & 0.01 & 0.18 & 0.11 & 2.04 & 1.90 & 0.85 \\
4 & 1.05 & 1.44 & 0.13 & 0.36 & 0.25 & 0.80 & 0.33 & 1.86 & 0.78 \\
5 & 0.95 & 1.92 & 0.05 & 0.34 & 0.20 & 0.53 & 1.02 & 0.92 & 0.74 \\
6 & 1.07 & 1.44 & 0.01 & 0.44 & 0.22 & 2.00 & 4.22 & 1.42 & 1.35 \\
7 & 0.44 & 0.42 & 0.06 & 0.35 & 0.33 & 0.75 & 2.48 & 0.46 & 0.66 \\
8 & 0.85 & 0.05 & 0.07 & 0.16 & 0.22 & 0.52 & 1.47 & 1.42 & 0.60 \\
9 & 1.61 & 0.92 & 0.01 & 0.25 & 0.36 & 0.11 & 0.66 & 3.41 & 0.92 \\
10 & 0.38 & 1.52 & 0.02 & 0.33 & 0.32 & 0.66 & 0.99 & 2.87 & 0.89 \\
11 & 0.09 & 0.32 & 0.003 & 0.69 & 0.42 & 0.69 & 1.22 & 2.74 & 0.77 \\
12 & 1.65 & 0.75 & 0.16 & 0.34 & 0.39 & 0.56 & 0.33 & 4.76 & 1.12 \\
13 & 1.46 & 0.80 & 0.07 & 0.22 & 0.32 & 0.83 & 0.99 & 2.27 & 0.87 \\
14 & 1.60 & 0.88 & 0.01 & 0.09 & 0.32 & 0.34 & N/A & N/A & 0.54 \\ Avg & 0.96 & 0.94 & 0.06 & 0.28 & 0.27 & 0.58 & 1.31 & 2.17 & - \\ \hline \hline \end{tabular} Total avg. error (%)  
\end{table} 
Table 2: Predicted parameters for Osong test track fifth bridge. **Author Contributions:** Conceptualization, H.Y. and J.J.P. ; methodology, J.H.L. ; software, J.H.L. ; validation, J.H.L., J.J.P. ; formal analysis, J.H.L. ; investigation, H.Y. and J.H.L. ; resources, J.J.P. ; data curation, J.J.P. ; writing--original draft preparation, J.H.L. ; writing--review and editing, H.Y. ; visualization, J.H.L. ; supervision, H.Y. ; project administration, H.Y. ; funding acquisition, J.J.P. All authors have read and agreed to the published version of the manuscript.