SymRegFlow: Symmetry-Regularized Flow Matching for Video World Models
Authors: Xi Ye, Yuzhu Wang, Xiaoyang Liu, Jiayi Wang, Yangyang Xu, Ruyu Wang, Wenlin Chen, Duo Su, Jun Zhu
Organizations: Dept. of Comp. Sci. and Tech., Tsinghua-Bosch Joint ML Center, Tsinghua University · University of Chinese Academy of Sciences · Bosch Center for Artificial Intelligence (BCAI) · Robert Bosch GmbH · Bosch (China) Investment Ltd.
Flow-matching-based multi-view world models generate realistic videos, but are commonly restricted to fixed camera rigs. Extending them to continuously varying camera poses requires paired pose--video observations with dense pose coverage, which are costly to acquire. We introduce SymRegFlow, a symmetry-regularized flow-matching framework for multi-view-consistent video generation across continuous viewpoints without ground-truth novel-view RGB supervision. For each target pose, SymRegFlow geometrically warps source views into noisy anchors and combines masked dual-anchor supervision with cross-anchor denoising-output consistency to mitigate anchor-specific errors. Under an affine Gaussian surrogate, we prove that suitable consistency regularization recovers the clean-reference optimum at fixed noise levels, strictly outperforming single- and merged-anchor baselines. Experiments on Cosmos-Drive-Dreams and nuScenes demonstrate high-quality, multi-view-consistent autonomous-driving video generation: on nuScenes, SymRegFlow achieves the lowest FVD and FVMD among the evaluated baselines, reducing FVD by over 31% relative to the best baseline, and source-conditioned inference also attains the best FID and instance preservation.
Figures & tables
Figure 1: SymRegFlow pipeline. Two observed videos x1,x2 are independently warped to the same requested novel view, yielding noisy anchors A1,A2 . The resulting multi-view pseudo-examples are corrupted with shared noise and fed into the same denoiser with directed cross-view attention (DCVA). VAE of latent flow-matching is omitted from the drawing for clarity.
Figure 2: SE(2) MNIST toy study. (a) Viewpoint-dependent noisy anchors A1,A2 , their mask-weighted fusion AM , and exact target xn . (b) SSIM and FD versus novel pose α (top) and base distortion Eb (bottom), averaged over five distortion levels and nine poses, respectively. FD denotes pixel-space Fréchet distance on flattened 16×16 pixel features.
Figure 3: Qualitative results on Cosmos-Drive-Dreams. Top: existing and generated novel views at one timestamp. Bottom: novel-view frames and existing-view sequences for seeds 0 and 42.
Method
FID ↓
FVD ↓
FVMD ↓
VBench Subj. ↑
VBench Bg. ↑
VBench Flicker. ↑
VBench IP ↑
MEt3R ↓
DiST-4D ( Guo et al., 2025 )
34.59
231.95
5381.67
88.72
91.81
95.67
92.78
0.3362
OmniRe ( Chen et al., 2025 )
44.58
291.99
3104.05
90.20
93.50
95.65
96.11
0.3177
GEN3C ( Ren et al., 2025b )
40.28
289.24
6144.97
88.39
92.66
95.34
37.78
0.3054
FreeVS ( Wang et al., 2025 )
20.60
258.53
4216.99
88.79
91.64
96.04
88.33
0.2829
Ours ( joint-generated )
22.00
158.62
2519.17
90.13
93.32
96.25
96.11
0.2818 †
Ours ( source-cond. )
19.22
159.02
2932.87
90.17
93.32
95.82
99.44
0.2920
Table 1: Novel-view generation on all 30 nuScenes validation scenes at the interpolated midpoint ( α=0.5 ) between two observed camera views. VBench scores are multiplied by 100. † MEt3R is computed using generated existing-view videos; other MEt3R scores use captured views. Bold : best; underline : second-best within each column, ranked at full precision.
Figure 4: Qualitative comparison of novel-view synthesis on nuScenes. The last row shows source-cond. SymRegFlow results for a fair comparison with the baselines.
Model
Anchors
DCVA
λc
Existing view
Novel view
Left
Right
Merge
FVD ↓
FVD ↓
VBench Subj. ↑
VBench Bg. ↑
MEt3R ↓
Anchor baselines
AL
✓
✓
–
238.14
562.23
87.86
90.36
0.2955
AR
✓
✓
–
198.86
605.63
88.79
92.20
0.3512
AM
✓
✓
–
213.97
704.32
87.71
91.78
0.2787
SymRegFlow variants (ours)
Table 2: Ablation study on four nuScenes scenes. λc is the consistency regularization weight (–: not applicable). The superscript ‘FA’ in C0.05FA denotes full attention without DCVA. VBench scores are multiplied by 100. Bold : best; underline : second-best.
Figure 5: Examples of attention bias in anchor baselines. AL and AR copy workers from source-supported regions (cyan boxes) into missing regions (red boxes); green shading indicates anchor-visible regions. The colorbar shows attention strength as a multiple of uniform attention.
Appendix figures & tables10 assets
Supplementary material from the paper’s appendix.
Appendix
Figure 6: Analytic clean-reference excess risk for Proposition 1 at α∈{0.35,0.50,0.65} . The horizontal baselines use the optimal unregularized predictors; the SymRegFlow curve uses the optimal predictor for each consistency strength ( λ in the plot denotes λc ). The midpoint makes left/right risks equal, and mirrored viewpoints exchange them. SymRegFlow has zero excess risk at λc⋆=4 and strictly improves on all three baselines in a neighborhood of that strength. These are evaluations of the surrogate formulas, not additional MNIST measurements.
Figure 7: Consistency-weight profiles using the five metrics in Table 2 , normalized against all 11 variants at iteration 2,048. Outward is better. Solid polygons show the 50/50 rank–min–max hybrid, dashed polygons its rank component, and crosses its min–max component. E/N denote existing/novel views; VB denotes VBench. Spoke values follow the table’s precision and scaling (VBench ×100 ); the mean is the arithmetic average of the five normalized spokes.
Paired anchor
Cross-view route gap Gxv
Within-frame mass PU→V
Single
SymRegFlow
Reduction
Single
SymRegFlow
Δ
Relative excess
Left
0.729
0.307
57.8%
0.1745
0.1447
+0.0298
+20.6%
Right
0.865
0.307
64.5%
0.2091
0.1877
+0.0214
+11.4%
Appendix
Table 3: Attention bias in the controlled one-scene overfitting experiment. The cross-view columns report the absolute novel-to-left/right QK route gap Gxv (lower is more symmetric), averaged over three relative-offset axes. The within-frame columns report invisible-to-visible attention mass PU→V under an identical paired visibility mask; Δ and the relative excess are single-anchor minus SymRegFlow.
Figure 8: Cross-view relative-offset QK profiles for novel-to-left (top) and novel-to-right (bottom) routes. Curves are count-weighted means over valid token pairs and are further averaged over captured denoising steps, DiT blocks, and heads. Single-anchor adaptation preferentially raises compatibility with its fine-tuning source; SymRegFlow reduces this source-dependent route imbalance.
Figure 9: Zero-offset cross-view QK compatibility over denoising. The rightmost panel reports the signed route bias, novel-to-left minus novel-to-right. Its sign follows the fine-tuning anchor for both single-anchor models, while SymRegFlow has a smaller, stable residual imbalance.
Figure 10: SymRegFlow consistency regularization weight sweep against exact held-out rotations (top) and pseudo targets (bottom). The dashed line indicates the selected λc=2 ; stars mark the best sampled weight for each metric. FD denotes pixel-space Fréchet distance on 16×16 pixel features.
Figure 11: Qualitative novel-view comparison on nuScenes scene-0012 between the front and front-right cameras.
Figure 12: Qualitative novel-view comparison on nuScenes scene-0013 between the front and front-right cameras.
Figure 13: Qualitative novel-view comparison on nuScenes scene-0014 between the front and front-right cameras.
Figure 14: Qualitative novel-view comparison on nuScenes scene-0014 between the back and back-left cameras.
Flow-matching models generate samples through iterative velocity predictions, but typically do not revisit these predictions using the intermediate representations that produced them. We introduce CorrFlow, a self-correcting flow-matching framework that reuses this information through a lightweight refiner. Under rectified-flow interpolation, the error of the one-step clean prediction equals the realized velocity residual scaled by the noise level. Motivated by this identity, the refiner learns to predict residual corrections from the base model's clean prediction, conditioning, noise level and hidden states from the same forward pass. The correction is added to the base velocity before each sampling update, so subsequent predictions are made from the corrected state. This requires no additional base-model evaluations and only one lightweight refiner evaluation per step. Our theoretical analyses establish conditions under which feature reuse outperforms raw-input affine predictors and refiner training achieves greater residual-risk reduction than continued base-model training under a matched training compute budget. Experiments on class-conditional image generation, text-to-video generation and image-to-video generation show consistent improvements over the corresponding base models, including gains in visual quality and physical consistency. Project Page: https://fogradio.github.io/corrflow-project
Hangwei Zhang, Nathan Rouillé, Chuanxia Zheng
PVG, Nanyang Technological University · Télécom Paris, Institut Polytechnique de Paris
Generating geometrically consistent videos remains an open challenge: text-to-video diffusion models trained on web-scale data treat geometry only implicitly, leading to object deformation, texture drift, and non-rigid backgrounds under camera motion. Existing solutions either improve consistency as a byproduct, apply only to static scenes or realign the latent space of the model completely. We introduce a geometry-consistency reward that directly measures whether motion in a generated video is compatible with a coherent scene. Our key insight is that in physically consistent videos, background motion should be explainable by rigid camera-induced flow, while independently moving objects should preserve appearance identity along motion trajectories. We operationalize this using optical flow, depth--pose predictions, and feature-based correspondence to separate rigid and dynamic regions and evaluate their respective consistency. Integrating this reward with reinforcement fine-tuning transforms geometric consistency from an emergent property into an explicit optimization objective for video generators. The approach is model agnostic and applies to diverse dynamic scenes containing both camera and object motion. Experiments show substantial reductions in temporal geometric artifacts over strong baselines while preserving perceptual quality. Code and model weights are published.
Novel view synthesis from sparse images must reconcile faithful reconstruction of observed regions with plausible completion of unseen content, while maintaining world consistency across viewpoints. Existing geometry-based methods preserve observed scene structure but often struggle to complete unseen regions, whereas video generative models offer rich appearance priors but accumulate inconsistencies during sequential view generation. We propose GeoVerse, a framework that synthesizes world-consistent novel views by performing generation within the geometric latent space of a pretrained 3D foundation model and injecting appearance priors from a video generative model. Specifically, GeoVerse extracts multilevel features from Wan2.2 VACE and injects them into the geometric latent diffusion model via a ControlNet-style adapter, incorporating video-learned appearance priors to enhance structural completion. To enforce cross-view coherence, a global spatial memory continuously aggregates observed and synthesized content, reprojecting target-aligned guidance to anchor subsequent predictions to a shared scene representation. Extensive experiments across diverse datasets demonstrate improved visual quality and geometric consistency, with a 2.23 dB higher PSNR on DL3DV and 32.4% lower ATE on Mip-NeRF360 compared to GLD.
Kerui Ren, Tao Lu, Linning Xu +5
Shanghai Jiao Tong University · Shanghai Artificial Intelligence Laboratory · The Chinese University of Hong Kong +3