Levy-Driven Correspondence Estimation for Registration
Authors: Qianliang Wu, Jiaqi Yang, Wankou Yang, Le Hui, Jin Xie, Jian Yang, Yaqing Ding
Organizations: Nantong University · Northwestern Polytechnical University · Southeast University · Nanjing University · Nanjing University of Science and Technology
Finding reliable point correspondences is difficult when point clouds have low overlap or undergo non-rigid deformation. Iterative refinement can correct uncertain matches, but costly network evaluations limit the number of updates. We present LevyMatch, a Lévy-driven method that uses random jumps to refine a soft matching matrix. At each step, a network uses the current matching state and geometric information to predict a target matching matrix. A Brownian reference bridge gives an explicit formula for the update toward this target. A Gamma random clock sets the time step for each update. The updated matches provide new geometric feedback for the next target prediction. We further propose a fixed front-loaded Gamma policy that assigns more expected clock time to early updates and less to later ones, without retraining or extra network evaluations. Reordering the same sampled Gamma increments shows that placing larger increments early gives higher accuracy than placing them late. On 4DMatch and 4DLoMatch, our method improves both non-rigid feature matching recall (NFMR) and inlier ratio (IR) over the compared methods. The front-loaded policy achieves 93.09% NFMR and 92.11% IR on 4DMatch, and 82.79% NFMR and 79.07% IR on 4DLoMatch.
Figures & tables
Figure 1 : Matching-matrix bridge and inference procedure. (a) Example paths for Random Gamma (blue) and Fixed front-loaded Gamma (orange), both starting from the lifted matrix X0 . Superscripts r and f identify the two clock policies, respectively, and h denotes the current resolution. Subscript k is the current state index. Numbers mark the first three updated states. Diamonds show endpoint predictions Yk , and squares show final outputs Yh . Bars show expected clock increments, not individual samples: E[ΔGk]=1/K for Random Gamma and E[ΔGk]=wk for Fixed front-loaded Gamma. The normalized weights are defined in Eq. ( 9 ). The paths explain the intended effect of early time allocation; they are not measured trajectories. (b) The shared endpoint predictor Hϕ estimates Yk from the current state and geometric input. A clock-controlled update then gives Xk+1 for the next prediction. Here αk=ΔGk+1/Rk , and Rk=T−Uk is the remaining operational time. The variance Vk+1 is given in Eq. ( 12 ), and zk∼N(0,I) is newly sampled Gaussian noise. Stochastic updates use k=0,…,K−2 . The last of the K endpoint evaluations returns Yh=YK−1 without another stochastic update.
4DMatch
4DLoMatch
Method
NFMR ↑
IR ↑
NFMR ↑
IR ↑
PointPWC [ wu2019pointpwc ]
21.60
20.00
10.00
7.20
FLOT [ puy2020flot ]
27.10
24.90
15.20
10.70
D3Feat [ 3 ]
55.50
54.70
27.40
21.50
Predator [ huang2021predator ]
56.40
60.40
32.10
27.50
Lepard [ li2022lepard ]
83.60
82.64
66.63
55.55
Table 1 : Correspondence results on 4DMatch and 4DLoMatch (%). Baseline values are from the cited papers. Both LévyMatch policies use the same checkpoint. LévyMatch rows report mean ± population standard deviation over three inference seeds. Fixed front-loaded Gamma uses β=2 .
4DMatch
4DLoMatch
Variant
Clock
NFMR ↑
IR ↑
NFMR ↑
IR ↑
Full checkpoint, Random/SDE
Gamma
92.88±0.08
91.95±0.06
82.32±0.18
78.61±0.17
Full checkpoint, uniform/SDE
uniform
92.82±0.09
91.89±0.07
82.32±0.34
78.61±0.32
Full checkpoint, uniform/ODE
uniform
92.85±0.05
91.91±0.06
82.21±0.23
78.47±0.18
Table 2 : Inference-clock and noise controls. All rows use the same checkpoint and endpoint-network evaluation budget. Only the inference clock or transition noise changes.
4DMatch
4DLoMatch
Initialization
Lévy matrix bridge
NFMR ↑
IR ↑
NFMR ↑
IR ↑
Random valid matrix
✓
92.30±0.12
91.46±0.09
82.94±0.09
79.39±0.10
Lifted DDIM-5
–
48.54
36.06
34.79
18.13
Lifted DDIM-5
✓
92.88±0.08
91.95±0.06
82.32±0.18
78.61±0.17
Table 3 : Initial-matrix and bridge-bypass controls using the same checkpoint. Rows with the bridge report results over three inference seeds. The bypass row uses seed 0.
4DMatch
Clock order
NFMR ↑
IR ↑
Δ Entropy
Δ Geo. ↓
Uniform/ODE (seed 0)
92.79
91.85
-0.5294
-0.0318
Gamma, random
92.88±0.08
91.95±0.06
−0.5291±0.0006
−0.0313±0.0002
Gamma, large early
93.23±0.09
92.23±0.06
−0.5402±0.0005
−0.0322±0.0001
Gamma, large late
92.23±0.14
91.41±0.13
−0.5040±0.0007
−0.0296±0.0002
4DLoMatch
Table 4 : Increment-order diagnostic. Gamma rows use the same sampled increment values for each seed and report three-seed results. The uniform row uses deterministic mean updates and seed 0. Δ Entropy and Δ Geo. are final-minus-initial changes in mean row entropy (nats) and weighted mean Euclidean alignment residual (point-coordinate units), respectively. Their definitions are given in Eqs. ( 13 )–( 15 ). Matching entropy does not measure accuracy.
4DMatch
4DLoMatch
Clock
β
NFMR ↑
IR ↑
NFMR ↑
IR ↑
Random Gamma
0
92.88±0.08
91.95±0.06
82.32±0.18
78.61±0.17
Fixed front-loaded
0.5
92.87±0.10
91.93±0.09
82.58±0.17
78.86±0.16
Fixed front-loaded
1.0
92.96±0.09
92.00±0.07
82.63±0.08
78.92±0.05
Fixed front-loaded
2.0
93.09±0.07
92.11±0.05
82.79±0.19
79.07±0.18
Fixed front-loaded
4.0
93.17±0.07
92.19±0.05
82.98±0.26
79.21±0.23
Table 5 : Effect of front-loading strength over three inference seeds. All settings use the same checkpoint. Increments are sampled from the assigned Gamma distributions without sorting.
Dataset
Clock
Time (ms) ↓
Matches
Empty (%) ↓
4DMatch
Random Gamma
479.8
648.82
0.00
4DMatch
Fixed front-loaded ( β=2 )
500.9
650.33
0.00
4DLoMatch
Random Gamma
493.2
379.99
0.00
4DLoMatch
Fixed front-loaded ( β=2 )
481.8
380.18
0.00
Table 6 : Recursive inference cost and output coverage for the main comparison. Fixed front-loaded Gamma uses β=2 . Both policies use 20 endpoint-network evaluations. Values are means over inference seeds 0, 1, and 2. Time includes the backbone, coarse DDIM source, and matrix-bridge solver, but excludes the downstream deformation solver. Matches is the number of retained correspondences per pair. Empty is the percentage of pairs with no retained matches.
Figure 2 : Selected qualitative comparisons on 4DMatch. LévyMatch uses Fixed front-loaded Gamma with β=2 and inference seed 0. For each pair, the left column shows the inputs before registration. The upper row shows interpolated test-point correspondences. The lower row shows the warped source (yellow) and target (blue). Green lines mark endpoint errors below 0.04 in dataset coordinate units; red lines mark errors at or above this threshold. The clouds are shown apart in the input and correspondence views. Camera views differ across panels.
Figure 3 : Selected qualitative comparisons on 4DLoMatch, using the layout and correctness threshold of Fig. 2 . LévyMatch uses Fixed front-loaded Gamma with β=2 and inference seed 0. The Pumpkinhulk example still has incorrect correspondences and visible warp errors around the extended limbs.
Department of Aerospace Intelligent Science and Technology, School of Astronautics, Beihang University, Beijing 100191, China, and also with the Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technologies, Ministry of Education