Organizations: Fujian Key Laboratory of Urban Intelligent Sensing and Computing · Key Laboratory of Multimedia Trusted Perception and Efficient Computing, Ministry of Education of China, School of Informatics, Xiamen University, China · School of Engineering Mathematics and Technology, University of Bristol
LiDAR relocalization has attracted increasing attention as it can deliver accurate 6-DoF pose estimation in complex 3D environments. Recent learning-based regression methods offer efficient solutions by directly predicting global poses without the need for explicit map storage. However, these methods often struggle in challenging scenes due to their equal treatment of all predicted points, which is vulnerable to noise and outliers. In this paper, we propose LEADER, a robust LiDAR-based relocalization framework enhanced by a simple, yet effective geometric encoder. Specifically, a Robust Projection-based Geometric Encoder architecture which captures multi-scale geometric features is first presented to enhance descriptiveness in geometric representation. A Truncated Relative Reliability loss is then formulated to model point-wise ambiguity and mitigate the influence of unreliable predictions. Extensive experiments on the Oxford RobotCar and NCLT datasets demonstrate that LEADER outperforms state-of-the-art methods, achieving 24.1% and 73.9% relative reductions in position error over existing techniques, respectively. The source code is released on https://github.com/JiansW/LEADER.
Figures & tables
Figure 1: Mean position error comparisons on NCLT and Oxford dataset. Our method achieves superior relocalization accuracy on both datasets.
Figure 2: The pipeline of the proposed LEADER. Raw point clouds undergo spatial transformation to establish yaw-invariant spatial representations. Hierarchical feature extraction then derives multi-level fused features by cyclic convolution. The Regressor processes features from the Robust Projection-based Geometric Encoder (RPGE) to output predict coordinates and reliability values, followed by Cartesian Recovery. During training, the Truncated Relative Reliability (TRR) loss optimizes predictions against ground truth. During inference, high-reliability points are selected via TRR filtering for robust 6-DoF pose estimation through RANSAC-based estimator.
Figure 3: Comparison of point cloud density distribution. Left: The point cloud is directly voxelized. Right: The point cloud is processed through the Spatial Transformation, voxelized, and then recovered via Cartesian Recovery.
Method
15-13-06-37
17-13-26-39
17-14-03-00
18-14-14-42
Average
APR
PointLoc [ 58 ]
10.75, 2.36
11.07, 2.21
11.53, 1.92
9.82, 2.07
10.79, 2.14
PosePN++ [ 67 ]
4.54, 1.83
6.44, 1.78
4.89, 1.55
4.64, 1.61
5.13, 1.69
HypLiLoc [ 57 ]
5.03, 1.46
4.31, 1.43
3.61, 1.11
2.61, 1.09
3.89, 1.27
DiffLoc [ 36 ]
2.03, 1.04
1.78, 0.79
2.05, 0.83
1.56, 0.83
1.86, 0.87
SCR
SGLoc [ 37 ]
1.79, 1.67
1.81, 1.76
1.33, 1.59
1.19, 1.39
1.53, 1.60
LiSA [ 62 ]
0.94, 1.10
1.17, 1.21
0.84, 1.15
0.85, 1.11
0.95, 1.14
Table 1: Mean position error (m) and mean orientation error (°) on the Quality-enhanced Oxford dataset . All values are given as (m, °). Lower values are better, with the best highlighted using bold and the second-best highlighted using underline. In both errors, LEADER achieved the best or second-best performance among all baselines.
Figure 4: Visualization results of part of the methods on trajectory 17-13-26-39 in Quality-enhanced Oxford dataset. The black and red points represent the true and predicted results, respectively. The star indicates the starting point.
Method
2012-02-12
2012-02-19
2012-03-31
2012-05-26
Average
APR
PointLoc [ 58 ]
7.23, 4.88
6.31, 3.89
6.71, 4.32
10.02, 5.32
7.57, 4.60
PosePN++ [ 67 ]
4.97, 3.75
3.68, 2.65
4.35, 3.38
9.59, 4.49
5.65, 3.57
HypLiLoc [ 57 ]
1.71, 3.56
1.68, 2.69
1.52, 2.90
2.90, 3.47
1.95, 3.16
DiffLoc [ 36 ]
0.99, 2.40
0.92, 2.14
0.98, 2.27
1.88 , 2.43
1.19 , 2.31
SCR
SGLoc [ 37 ]
1.20, 3.08
1.20, 3.05
1.12, 3.28
3.81, 4.74
1.83, 3.54
LiSA [ 62 ]
0.97 , 2.23
0.91 , 2.09
0.87, 2.21
3.30, 2.84
1.51, 2.34
Table 2: Mean position error (m) and mean orientation error (°) on the NCLT dataset . All values are given as (m, °). Lower values are better, with the best highlighted using bold and the second-best highlighted using underline. In both errors, LEADER achieved the best performance among all baselines.
Figure 5: Visualization results of part of the methods on trajectory 2012-05-26. The black and red points represent the true and predicted results, respectively. The star indicates the starting point.
Figure 6: All training trajectories and the 2012-05-26 test trajectory on NCLT dataset.
Figure 7: Cumulative distribution of position errors on NCLT dataset.
Method
<0.5m (%)
<1m (%)
99% Thresholds (m)
SGLoc
24.5
63.8
8.70
DiffLoc
30.8
68.7
5.73
LiSA
34.3
72.0
4.98
LightLoc
46.3
79.6
8.70
Ours
90.0
98.3
1.23
Table 3: Frame coverage comparison at critical error thresholds.
Method
ST
TRR-Train
TRR-Test
Normal Point Cloud
Yaw-Perturbed Point Cloud
Inference Time
Parameters
1
×
×
×
0.95, 1.94
8.04, 10.77
48
69.67 M
2
×
✓
×
0.89, 1.82
8.67, 10.44
48
69.67 M
3
×
✓
✓
0.88, 1.86
6.59, 10.14
48
69.67 M
4
✓
×
×
0.59, 2.12
0.59, 2.12
48
69.67 M
5
✓
✓
×
0.35, 1.80
0.35, 1.80
48
69.67 M
6
✓
✓
✓
0.31, 1.81
0.31, 1.81
48
69.67 M
Table 4: Ablation study evaluating the contributions of the RPGE and TRR modules on NCLT dataset. The ST column indicates the use of Spatial Transformation, while TRR-Train and TRR-Test denote the application of the TRR module during training and inference, respectively. Results for both normal and yaw-perturbed point clouds are reported as position/orientation errors (m, °), with inference time (ms) and parameters (M is million) included as an additional metric.
Figure 8: TRR Loss effect on Scene Point Error distribution on NCLT dataset 2012-05-26 trajectory.
Figure 9: Average Scene Point Error vs. Reliability Score Percentiles on NCLT dataset 2012-05-26 trajectory.
Test Condition
Error (m, °)
Baseline
0.31, 1.81
180° FOV
0.78, 3.51
Random Dropout (0 - 50%)
0.33, 1.86
Gaussian Noise ( σ=0.05 )
0.36, 1.93
Pitch/Roll Perturbation ( ±10∘ )
0.65, 3.17
Table 5: Robustness evaluation under various degraded sensing conditions on the NCLT dataset. All values represent the mean position and orientation errors.
Figure 10: Illustration of cylindrical projection and convolution correspondence. (a) Original point cloud P1 in Cartesian coordinates. (b) Projected point cloud P2 in cylindrical coordinates after Spatial Transformation. (c) The equivalent convolution operation in P1 corresponding to the rectangular convolution kernel applied on P2 , which forms a sector-shaped receptive field.
Figure 11: Overview of the proposed encoder architecture.
Figure 12: Illustration of the dilated cyclic sparse convolution used in stage 5 to enlarge the receptive field without reducing spatial resolution (right).
Yaw Angle
LEADER
LightLoc
DiffLoc
Original
0.31, 1.81
1.70, 2.95
1.19, 2.31
Yaw +180°
0.31, 1.81
21.70, 21.57
5.58, 36.36
Random Yaw
0.31, 1.81
30.51, 22.46
4.57, 76.50
Table 6: Localization results for the NCLT dataset at different yaw angles. All values are given as (m, °).
Method
Position Error
Orientation Error
Cylindrical projection
0.31 m
1.81°
Spherical projection
0.35 m (↑ 12.9%)
1.97°(↑ 8.8%)
Table 7: Performance comparison of coordinate systems
Figure 13: Visualization of Reliability scores. Points are color-coded by reliability (dark red: high, light/white: low).
Reliability Quartile
Error (m/°)
0-25% (Highest)
0.32, 1.96
25-50%
0.34, 1.97
50-75%
0.67, 2.33
75-100% (Lowest)
2.39, 3.63
Table 8: Mean position error (m) and mean orientation error (°) across reliability quartiles.
Metric
Position Error (m)
Orientation Error (°)
SGLoc (Original)
1.83
3.54
SGLoc + TRR
1.76 (↓ 3.83%)
2.61 (↓ 26.27%)
Table 9: Performance improvement by integrating TRR loss into SGLoc
Method
Error (m, °)
Mean Euclidean loss
0.59, 2.12
Matching loss
0.43, 1.97
TRR loss (Ours)
0.31, 1.81
Table 10: Performance comparison of different loss functions on NCLT dataset
Figure 14: Trajectory visualization of the NCLT dataset.
Metric
LEADER
LEADER (xy)
RING/RING++
MPE (m)
0.31
0.28
16.34
MOE (°)
1.81
1.03
10.45
MedPE (m)
0.24
0.21
0.27
Recall@1
—
—
75.07%
Success@5m
99.72%
99.72%
92.79%
Table 11: Comparisons of different methods on the NCLT dataset.
Figure 15: Ground truth trajectory visualization of Quality-enhanced Oxford dataset.
Table 12: Visualization on Quality-enhanced Oxford Dataset, the star indicates the starting point.
Table 13: Visualzation on NCLT Dataset, the star indicates the starting point.
Fujian Key Laboratory of Urban Intelligent Sensing and Computing, Xiamen University, Xiamen, China · School of Engineering Mathematics and Technology, University of Bristol, Bristol, United Kingdom
Institute of Visual Computing, Graz University of Technology, 8010 Graz, Austria · Neuromorphic Automation and Intelligence Lab (NAIL), School of Artificial Intelligence and Robotics, Hunan University, Changsha 410012, China