Figure 1.

Example of false positive detected by Scan context and triggered by our temporal verification module. Top figures: frame 4058 and 4180 of KITTI sequence 00. The vegetation on the right side makes them difficult to distinguish. Since the ground truth distance between these two frames is 148.64 m, they should not be considered as loop closure. Middle figures: colormap corresponding to scan context before segmentation. Bottom figures: segment scan context of corresponding frame represented by colormap. The left side of colormap indicates the preserved buildings, and the empty right side indicates that the vegetation has been removed. After segmentation, these two frames become distinguishable. If we directly use Scan context, the distance between them is 0.1488, resulting in false positive. Our segment scan context acquires a distance up to 0.327, thus, avoiding outliers.