LPA-CWM: A Learned Physical Adjudicator for Motion Reasoning with Counterfactual World Models
Authors: Kunwei Wu, Xiang Liu, Guocai Yao, Junming Chen, Zhikang Chen, Min Zhang, Pengwei Wang, Sen Cui
Organizations: National University of Singapore · Tsinghua University · Beijing Academy of Artificial Intelligence · The Hong Kong University of Science and Technology · University of Oxford · East China Normal University
Counterfactual world models (CWM) extract motion from pretrained video predictors by comparing factual and intervened predictions, but uniform aggregation weights responses equally without explicitly incorporating physical priors. Our key insight is to incorporate physical priors into candidate reliability learning, motivating LPA-CWM with a lightweight Learned Physical Adjudicator (LPA). Trained on dense MOVi-F trajectories, the 3.0M-parameter LPA compares visual context and response structure across an unordered candidate set to predict relative weights; windowed localization and one paired re-evaluation recover motion with the CWM frozen. Existing video-level benchmarks do not directly assess motion correspondence, where low localization error can conceal missing trajectory segments. We introduce Completeness-aware Motion Correspondence (CMC), a ground-truth-anchored protocol jointly measuring localization, completeness, visibility, and continuity, counting missing predictions as failures on visible dynamic points. Across DAVIS, Kinetics, and RoboTAP, LPA-CWM improves all main CMC measures over Uniform CWM, with relative gains of 18.1%--60.0% in average Dynamic Correspondence Accuracy (DCAavg), and improves TAP-Vid First tracking accuracy (overview: https://LPA-CWM.github.io).
Figures & tables
Figure 1: Overview of our work. Uniform CWM can suffer from three characteristic failures in motion reasoning: drifting from moving objects, being distracted by competing motion, and losing track under appearance changes. Our Learned Physical Adjudicator (LPA) identifies reliable counterfactual motion evidence, enabling LPA-CWM to recover more coherent trajectories. We further introduce the CMC protocol to evaluate motion correspondence across localization, completeness, visibility, and continuity. Compared with external methods, Uniform CWM, and APA-CWM, LPA-CWM performs strongly across all four dimensions.
Figure 2: Overview of APA-CWM and LPA-CWM. Given a source–target RGB frame pair (It,It+1) and a query point pt , a frozen CWM generates motion candidates {Δm} . APA-CWM derives candidate weights from the NSG-derived map P around candidate peaks pt+1(m) . LPA-CWM instead encodes local crops, full responses, the frame pair, and response statistics; the resulting tokens zm are processed by a trainable Set Transformer to predict weights. The weighted response undergoes windowed localization and one CWM re-evaluation to obtain refined motion. During LPA training, endpoint errors from MOVi-F trajectories are converted into soft targets q .
Figure 3: Windowed localization progressively suppresses distant modes. Top: flattened maps from π(0) to π(2) . Bottom: the corresponding 3D views.
Figure 4: Qualitative motion correspondence. Five methods are compared on identical frames and visible queries across manipulation, human-action, and animal-motion scenes. Badges report mean EPE in pixels. LPA-CWM yields accurate, coherent correspondences across the displayed cases.
Table 1: Cross-dataset evaluation on DAVIS, Kinetics, and RoboTAP. LPA is trained exclusively on MOVi-F and directly evaluated on all three datasets without adaptation. CMC metrics are percentages. For TAP-Vid First, AJ, <δavgx , and OA are percentages, while AD and MD are pixels. Bold marks the best result among the three CWM variants. Stronger external results are shaded separately.
Table 2: Ablations on DAVIS under CMC and TAP-Vid First. All configurations use M=10 and R=1 . Architecture and objective variants use windowed localization; “Std.” and “Win.” denote standard and windowed localization. Metric conventions follow Table 1 ; best values within each block are bold, enabling direct comparison across design choices.
Figure 6: Candidate weighting on MOVi-F validation videos. (a) Candidate-space weighted-coordinate EPE with video-macro means. (b) Weight versus ground-truth candidate rank; the inset reports top-1 hit rates. Error bars and shading show 95% video-cluster bootstrap intervals.
Appendix figures & tables8 assets
Supplementary material from the paper’s appendix.
Appendix
Dim.
Statistic
Definition
Support
1
Normalized vertical displacement
Candidate y displacement normalized by image height
Global
2
Normalized horizontal displacement
Candidate x displacement normalized by image width
Global
3
Endpoint response
Response magnitude at the candidate endpoint
Single pixel
4
Global response mean
Mean response magnitude
Full response
5
Global response standard deviation
Population standard deviation of response magnitude
Full response
6
Global response median
Median response magnitude
Full response
Appendix
Table A.1: Candidate scalar descriptor used by LPA. The support column indicates the spatial region used to compute each statistic.
Figure A.1: Evidence chain for the NSG-derived analytic precursor on a real frame pair. The reference frame and observed change define the temporal evidence; score magnitude and score–change alignment produce the analytic reliability map P . APA-CWM averages this map within a local neighborhood around CWM candidate peaks p^t+1(m) . LPA-CWM does not use the diffusion score map; it learns candidate reliability from the features described in Section 3.3 . Heatmaps are independently normalized for visualization.
Table C.1: Full threshold-wise CMC accuracy results on DAVIS, Kinetics, and RoboTAP. All entries use the same 0–100 scale as Table 1 . Cov. and [email protected] denote Coverage and [email protected]; CTS4 and CTS8 denote CTS@(4,0.8) and CTS@(8,0.8), respectively. Results follow the presentation convention of Table 1 .
Method
DAVIS
Kinetics
RoboTAP
VisBA ↑
OF1 ↑
LCC ↑
Frag. ↓
VisBA ↑
OF1 ↑
LCC ↑
Frag. ↓
VisBA ↑
OF1 ↑
LCC ↑
Frag. ↓
SMURF
56.64
14.92
83.29
21.54
62.69
35.11
82.40
9.66
57.17
28.66
78.28
16.35
GMRW
63.24
45.22
35.46
8.46
65.99
46.34
51.43
7.16
61.48
35.21
28.76
7.59
DODUO
58.94
45.83
28.44
12.88
78.37
58.39
59.83
16.82
73.28
53.09
47.15
17.33
CoTracker3
76.43
58.97
81.01
1.25
78.00
58.56
80.41
8.41
73.11
59.35
75.21
5.05
RAFT
70.16
41.66
62.02
7.62
74.93
60.72
71.71
9.38
70.60
44.27
69.46
22.24
Appendix
Table C.2: Visibility and continuity diagnostics for CMC on DAVIS, Kinetics, and RoboTAP. OF1 denotes occlusion F1. VisBA, OF1, and LCC are percentages; Frag. is the mean fragmentation count ×100 . Results follow the presentation convention of Table 1 .
Figure C.1: CMC threshold sensitivity on DAVIS. (a) DCA avg as the dynamic-track motion threshold varies over {2,4,8} pixels. (b) CTS@(4, c ) as the coverage threshold varies over {0.6,0.7,0.8,0.9} with Lmotion=4 pixels. Dashed vertical lines indicate the default settings.
Method
Visibility source
Threshold
Sampling
RAFT
Direct query-to-target forward–backward consistency
6 px
Forward at integer query; backward bilinear
SEA-RAFT
Direct query-to-target forward–backward consistency
6 px
Forward at integer query; backward bilinear
DODUO
Direct query-to-target forward–backward consistency
6 px
Forward at integer query; backward bilinear
CoTracker3
Native visibility from official offline predictor
0.9
Native sparse-query trajectory; no additional FB test
SMURF
Native occlusion map
0.5
Query-location lookup
GMRW
Official tracking utility with adjacent-frame forward–backward consistency
3 px
Bilinear at propagated positions
Appendix
Table D.1: Visibility adaptation for external estimators. Thresholds are defined on the corresponding evaluator grid.
Figure E.1: Joint sensitivity to mask count and paired re-evaluation depth. Full LPA-CWM results on 40 fixed MOVi-F query groups. (a) Final deployed endpoint EPE. (b) End-to-end inference time per query. R=0 omits paired re-evaluation; M=10,R=1 is the deployed setting.
Figure F.1: Additional qualitative results on fourteen cases distinct from Figure 4 . Columns show SEA-RAFT, CoTracker3, Uniform CWM, APA-CWM, and LPA-CWM in this order. Every method receives the same frame pair and the same five query identities. A method uses one color throughout; continuous lines connect source queries to target predictions, and badges report mean EPE over the displayed queries.
Point tracking follows selected or dense image points through video, enabling motion analysis, 3D reconstruction, and precise spatiotemporal understanding.