# A Novel Method for Building Displacement Based on Multipopulation Genetic Algorithm
## 4 Experiments and Evaluations
### Analysis and Evaluation of Experimental Results
Figure 7b shows a comparison of the original data and displacement results based on the IGA, where the grey polygons are the original building data, and the displacement results are represented by cyan polygons. The basic statistical information of the displacement results based on the IGA is listed in Table 4. Table 4 shows that the IGA had five unresolved conflicts between buildings and roads, located in block 2, block 4, and block 5. More seriously, the IGA generates secondary conflicts. Through comparison, it is found that the BDMPGA has a stronger ability to resolve spatial conflicts. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{3}{*}{**Block**} & \multirow{3}{*}{\begin{tabular}{c} **Building** \\ **Number** \\ \end{tabular} } & \multicolumn{3}{c}{**Initial**} & \multicolumn{3}{c}{**Final**} & \multirow{3}{*}{**Total**} \\ \cline{3-3} \cline{5-8}  & & **\begin{tabular}{c} **\textless{}B-B->** \\ **Conflict** \\ **Number** \\ \end{tabular} & \begin{tabular}{c} **\textless{}B-R->** \\ **Conflict** \\ **Number** \\ \end{tabular} & \begin{tabular}{c} **\textless{}B-R->** \\ **Conflict** \\ **Number** \\ \end{tabular} & \
\begin{tabular}{c} **\textless{}B-R->** \\ **Conflict** \\ **Number** \\ \end{tabular} &
\begin{tabular}{c} **\textless{}B-R->** \\ **Displacement** \\ **Distances (m)** \\ \end{tabular} \\ \hline
1 & 9 & 0 & 4 & 135 & 16 & 0 & 0 & 12.08 \\
2 & 26 & 1 & 15 & 390 & 64 & 0 & 3 & 29.88 \\
3 & 20 & 1 & 9 & 300 & 40 & 0 & 0 & 24.95 \\
4 & 23 & 0 & 13 & 345 & 52 & 0 & 2 & 35.57 \\
5 & 11 & 2 & 8 & 165 & 40 & 0 & 0 & 13.42 \\
6 & 14 & 0 & 11 & 210 & 44 & 0 & 0 & 24.39 \\ \hline  & 103 & 4 & 60 & 1545 & 256 & 0 & 5 & 140.31 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Statistical information of the displacement results based on the GA.  
Figure 6: Comparison diagram. (**a**) Displacement result using the GA (1:10,000); (**b**) Comparison result of the original data and displacement results based on the GA (1:10,000). Although these methods can be used to displace buildings and resolve spatial conflicts, they yield different displacement results (e.g., displacement distance and displacement direction) at some local regions. To better illustrate the differences in the displacement results of the various methods, we selected some typical regions to display the corresponding detailed information, such as the regions marked with red circles in Figures 5-7. Table 5 shows the detailed information of the displacement results in these typical regions using the proposed BDMPGA method and the two comparative methods (i.e., GA and IGA). Table 5 indicates the following:  
1. Compared with the GA and the IGA, the proposed BDMPGA can generate more reasonable displacement results. For example, as shown in local area No.A in Table 5, when a building is located at an acute corner and is conflicted with multiple roads, the BDMPGA can better solve the conflict by moving a longer distance, and the displacement direction is the resultant direction of multiple conflicting roads. When a building is located at an obtuse corner and is conflicted with multiple roads, as shown in local area No.B in Table 5, the BDMPGA will make the building move a short distance to resolve the conflict. However, the GA cannot resolve multiple conflicts and even aggravate the conflicts. The IGA method only resolves some of the conflicts. 2. The proposed BDMPGA has a better ability than the GA and IGA to maintain building positional accuracy. For example, as show in local area No.C in Table 5, the IGA tends to move long distances to resolve the conflict. However, the proposed BDMPGA only makes the conflict building move a shorter distance and satisfies the constraint condition of ensuring the positional accuracy of the  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{3}{*}{**Block**} & \multirow{3}{*}{ \begin{tabular}{c} **Initial** \\ **Number** \\ \end{tabular}  } & \multicolumn{2}{c}{**Final**} & \multirow{3}{*}{**MaxGen**} & \multirow{3}{*}{**Population**} & \multirow{3}{*}{**\