## 4 Experimental Results
### Metric Localization Results  
The results of the metric localization for our method and the comparison methods are presented in Table 6. Figure 12 shows the comparison of the localization trajectories and the cumulative error distribution between the three methods in the industrial park's underground parking scene, while Figure 13 displays the same data for the mall's underground parking scene. In the industrial park underground parking scene, our method achieved an average error in the range of [0.262 m, 0.429 m] for each experiment, with the percentage of nodes with errors less than 0.6 m ranging from 85.71% to 99.16%. In contrast, [PERSON]'s method had an average error in the range of [0.329 m, 1.158 m] for each experiment, with the percentage of nodes with errors less than 0.6 m ranging from 40.77% to 82.4%. PAN-SLAM had an average error in the range of [0.313 m, 0.492 m] for each experiment, with the percentage of nodes with errors less than 0.6 m ranging from 62.72% to 89.66%. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Scene**} & \multirow{2}{*}{**Loop Number**} & \multirow{2}{*}{**Method**} & \multicolumn{6}{c}{**Accuracy (\%)**} & \multicolumn{6}{c}{**Average Error (Frames)**} \\ \cline{3-10}  & & & & **Group 1** & **Group 2** & **Group 3** & **Group 4** & **Group 1** & **Group 2** & **Group 3** & **Group 4** \\ \hline \multirow{3}{*}{Industrial park} & \multirow{3}{*}{2 nd} & Ours & 95.81 & 95.81 & 95.53 & 96.09 & 0.045 & 0.047 & 0.050 & 0.047 \\  & & Tao’s & 77.37 & 75.14 & 60.34 & 70.11 & 0.246 & 0.285 & 0.860 & 0.419 \\  & & Ours & 94.77 & 93.03 & 94.43 & 93.38 & 0.059 & 0.080 & 0.070 & 0.080 \\  & & Tao’s & 63.76 & 60.98 & 41.81 & 56.10 & 0.415 & 0.498 & 1.268 & 0.662 \\ \hline \multirow{3}{*}{Mall} & \multirow{3}{*}{2 nd} & Ours & 95.36 & 95.50 & 95.63 & 95.43 & 0.053 & 0.052 & 0.053 & 0.059 \\  & & Tao’s & 49.62 & 49.62 & 48.65 & 48.58 & 1.030 & 1.063 & 1.046 & 1.086 \\ \cline{1-1}  & & Ours & 93.67 & 92.88 & 92.70 & 92.52 & 0.071 & 0.081 & 0.083 & 0.084 \\ \cline{1-1}  & & Tao’s & 44.99 & 45.66 & 42.34 & 44.15 & 1.184 & 1.198 & 1.235 & 1.238 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Comparison of the results for the different methods in nearest map node search. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Scene**} & \multirow{2}{*}{**Loop**} & \multirow{2}{*}{**Method**} & \multicolumn{6}{c}{**Average Error (m)**} & \multicolumn{6}{c}{**Percentage of Nodes with Error \textless{} 0.6 m (\%)**} \\ \cline{3-10}  & & & **Group 1** & **Group 2** & **Group 3** & **Group 4** & **Group 1** & **Group 2** & **Group 3** & **Group 4** \\ \hline \multirow{4}{*}{Industrial park} & Ours & 0.262 & 0.281 & 0.364 & 0.300 & 99.16 & 98.32 & 90.50 & 94.69 \\  & 2 nd & Tao’s & 0.329 & 0.362 & 0.803 & 0.503 & 82.40 & 81.28 & 60.89 & 75.70 \\  & & PAN-SLAM & 0.313 & 0.416 & 0.313 & 0.416 & 89.66 & 73.18 & 89.66 & 73.18 \\  & & Ours & 0.339 & 0.352 & 0.429 & 0.372 & 97.56 & 95.47 & 85.71 & 94.43 \\  & 3 rd & Tao’s & 0.542 & 0.579 & 1.158 & 0.725 & 64.11 & 62.37 & 40.77 & 59.23 \\  & & PAN-SLAM & 0.404 & 0.492 & 0.404 & 0.492 & 74.22 & 62.72 & 74.22 & 62.72 \\ \hline \multirow{4}{*}{Mall} & \multirow{2}{*}{2 nd} & Ours & 0.355 & 0.362 & 0.362 & 0.357 & 91.27 & 90.85 & 90.51 & 91.55 \\  & & Tao’s & 1.155 & 1.179 & 1.193 & 1.171 & 16.22 & 14.48 & 15.32 & 14.83 \\  & & PAN-SLAM & 0.587 & 0.731 & 0.587 & 0.731 & 53.43 & 43.24 & 53.43 & 43.24 \\  & & Ours & 0.373 & 0.372 & 0.408 & 0.396 & 88.96 & 89.02 & 83.84 & 85.52 \\  & 3 rd & Tao’s & 1.267 & 1.267 & 1.432 & 1.354 & 11.84 & 10.98 & 9.83 & 10.01 \\  & & PAN-SLAM & 0.661 & 0.754 & 0.661 & 0.754 & 49.19 & 41.80 & 49.19 & 41.80 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Comparison of the results for the different methods in the metric localization. Figure 12: Comparison of the metric localization results between our method and the comparison methods in the industrial park’s underground parking scene.