FL4N: Feed-forward Latent Model for 4D Novel View Synthesis
Organizations: 1KAIST AI · 2Google DeepMind
Abstract
4D novel view synthesis (NVS) aims to render dynamic scenes across viewpoints and timestamps, which requires jointly inferring 3D structure and temporal dynamics. Existing monocular feed-forward methods often rely on explicit 4D Gaussian representations, which are prone to temporal inconsistency and severe rendering artifacts. We present FL4N, the first feed-forward latent 4D NVS model. Instead of relying on explicit 4D primitives, FL4N encodes a 4D scene prior into a unified latent representation across space and time. Our core insight is that learning temporal dynamics as residuals on top of a pretrained static latent prior enables effective 4D modeling with limited dynamic training data. To this end, we introduce a lightweight dynamic encoder that leverages static scene features to disentangle object motion from camera-induced parallax. Trained solely with an image synthesis objective, FL4N achieves state-of-the-art 4D NVS quality while rendering in real time. Its learned latent representation generalizes to real-world videos and disentangles viewpoint from time.
Figures & tables
| Method | Pose | NVIDIA | N3DV | Kubric4D | CamxTime | Charge | ||||||||||
| PSNR | SSIM | LPIPS | PSNR | SSIM | LPIPS | PSNR | SSIM | LPIPS | PSNR | SSIM | LPIPS | PSNR | SSIM | LPIPS | ||
| Feed-forward Gaussian Representation | ||||||||||||||||
| 4DGT ( Xu et al., 2025 ) | ✓ | 16.127 | 0.3884 | 0.5972 | 17.813 | 0.6609 | 0.5131 | 14.148 | 0.5027 | 0.6096 | 17.125 | 0.6557 | 0.4893 | 18.017 | 0.7786 | 0.5653 |
| MoVieS ( Lin et al., 2026a ) | ✓ | 11.818 | 0.2546 | 0.6760 | 20.136 | 0.7045 | 0.4605 | 12.411 | 0.3550 | 0.6070 | 17.069 | 0.6223 | 0.4488 | 18.709 | 0.7473 | 0.5298 |
| NeoVerse † ( Yang et al., 2026 ) | ✗ | 15.050 | 0.4135 | 0.4626 | 12.953 | 0.4806 | 0.5697 | 8.954 | 0.2573 | 0.6721 | 10.432 | 0.3110 | 0.5905 | 15.224 | 0.5211 | 0.5919 |
| C4G † ( Kim et al., 2026c ) | ✗ | 16.572 | 0.4182 | 0.6203 | 18.444 | 0.7050 | 0.5246 | 14.931 | 0.5656 | 0.6442 | 20.527 | 0.7056 | 0.4369 | 18.535 | 0.7797 | 0.5279 |
| Method | Pose | NVIDIA | N3DV | Kubric4D | CamxTime | Charge | ||||||||||
| PSNR | SSIM | LPIPS | PSNR | SSIM | LPIPS | PSNR | SSIM | LPIPS | PSNR | SSIM | LPIPS | PSNR | SSIM | LPIPS | ||
| Feed-forward Gaussian Representation | ||||||||||||||||
| 4DGT ( Xu et al., 2025 ) | ✓ | 15.937 | 0.3867 | 0.6052 | 16.097 | 0.6380 | 0.5483 | 15.680 | 0.5424 | 0.5786 | 17.024 | 0.6573 | 0.4939 | 17.939 | 0.7756 | 0.5617 |
| MoVieS ( Lin et al., 2026a ) | ✓ | 15.785 | 0.4614 | 0.5328 | 19.710 | 0.7400 | 0.4414 | 16.988 | 0.6368 | 0.4174 | 17.340 | 0.6470 | 0.4224 | 20.113 | 0.7771 | 0.5084 |
| NeoVerse † ( Yang et al., 2026 ) | ✗ | 14.449 | 0.3819 | 0.4890 | 12.447 | 0.4729 | 0.5681 | 8.885 | 0.2256 | 0.6793 | 10.276 | 0.3091 | 0.5911 | 15.220 | 0.5380 | 0.5940 |
| C4G † ( Kim et al., 2026c ) | ✗ | 16.403 | 0.4096 | 0.6304 | 17.039 | 0.6829 | 0.5374 | 15.270 | 0.5572 | 0.6348 | 20.175 | 0.7009 | 0.4453 | 18.410 | 0.7640 | 0.5324 |
| Method | Pose | DyCheck | ADT | TUM | ||||||
| PSNR | SSIM | LPIPS | PSNR | SSIM | LPIPS | PSNR | SSIM | LPIPS | ||
| Feed-forward Gaussian Representation | ||||||||||
| 4DGT ( Xu et al., 2025 ) | ✓ | 13.743 | 0.4079 | 0.6233 | 16.710 | 0.4999 | 0.5651 | 14.380 | 0.4468 | 0.5612 |
| MoVieS ( Lin et al., 2026a ) | ✓ | 11.755 | 0.3420 | 0.6428 | 15.432 | 0.4698 | 0.5828 | 15.683 | 0.5079 | 0.4426 |
| NeoVerse † ( Yang et al., 2026 ) | ✗ | 16.756 | 0.4663 | 0.4566 | 16.179 | 0.4384 | 0.5296 | 16.120 | 0.5266 | 0.3981 |
| C4G † ( Kim et al., 2026c ) | ✗ | 15.755 | 0.4735 | 0.6111 | 18.900 | 0.5813 | 0.5833 | 17.508 | 0.5518 | 0.4951 |
| Variant | Components | Full frame | Dynamic region | |||||||
| Residual branch | Static anchoring | Mask loss | Frozen renderer | PSNR | SSIM | LPIPS | PSNR | SSIM | LPIPS | |
| (i) | ✗ | – | ✗ | ✗ | ||||||
| (ii) | ✓ | ✓ | ✓ | ✗ | ||||||
| (iii) | ✓ | ✓ | ✗ | ✓ | ||||||
| (iv) | ✓ | ✗ | ✓ | ✓ | ||||||
| FL4N | ✓ | ✓ | ✓ | ✓ | 23.666 | 0.7734 | 0.2369 | 14.264 | 0.5192 | 0.4189 |
| Method | sec / view | FPS | PSNR |
| 4DGT | 0.040 | 25.00 | 12.15 |
| MoVieS | 0.037 | 27.02 | 14.10 |
| NeoVerse | 0.027 | 37.03 | 10.74 |
| NeoVerse † | 14.127 | 0.07 | 13.86 |
| C4G | 0.036 | 27.77 | 14.25 |
| C4G † | 23.885 | 0.04 | 16.76 |
| Region | Feat. | 1 | 4 | 16 | |
| All | 27.33 | 5.65 | 25.37 | 53.40 | |
| 29.04 | 5.76 | 26.50 | 57.64 | ||
| ( 1.71) | ( 0.11) | ( 1.13) | ( 4.24) | ||
| Dyn | 23.45 | 3.10 | 21.14 | 49.03 | |
| 25.29 | 3.12 | 22.37 | 53.68 | ||
| ( 1.84) | ( 0.02) | ( 1.23) | ( 4.65) |
| Region | Feat. | 4 | 8 | ||
| AbsRel | AbsRel | ||||
| All | 0.0944 | 0.8908 | 0.0868 | 0.9081 | |
| 0.0863 | 0.9035 | 0.0751 | 0.9326 | ||
| ( 0.0081) | ( 0.0127) | ( 0.0117) | ( 0.0244) | ||
| Dyn | 0.1178 | 0.8699 | 0.1149 | 0.8790 | |
| 0.1050 | 0.8941 | 0.0996 | 0.9099 | ||
Appendix figures & tables26 assets
Supplementary material from the paper’s appendix.
Appendix
| Method | Pose | NVS | CTVS | ||||||||||
| Kubric4D | Charge | Kubric4D | Charge | ||||||||||
| PSNR | SSIM | LPIPS | PSNR | SSIM | LPIPS | PSNR | SSIM | LPIPS | PSNR | SSIM | LPIPS | ||
| Feed-forward 4D Gaussian Representation | |||||||||||||
| 4DGT ( Xu et al., 2025 ) | ✓ | 12.089 | 0.2406 | 0.0305 | 17.703 | 0.6516 | 0.1127 | 12.405 | 0.2557 | 0.0303 | 17.708 | 0.6588 | 0.1157 |
| MoVieS ( Lin et al., 2026a ) | ✓ | 11.401 | 0.1741 | 0.0318 | 17.969 | 0.6079 | 0.1130 | 11.797 | 0.2034 | 0.0307 | 18.068 | 0.6119 | 0.1147 |
| NeoVerse † ( Yang et al., 2026 ) | ✗ | 10.847 | 0.1527 | 0.0381 | 16.292 | 0.5161 | 0.1242 | 10.254 | 0.1372 | 0.0403 | 16.152 | 0.4966 | 0.1307 |
| Method | DAVIS-2016 | DAVIS-2017 | DAVIS-all | |||||||||
| JM | JR | FM | FR | JM | JR | FM | FR | JM | JR | FM | FR | |
| Easi3R ( Chen et al., 2025 ) | 50.10 | 55.77 | 43.40 | 37.25 | 46.86 | 50.54 | 39.06 | 30.05 | 44.10 | 50.85 | 35.16 | 27.24 |
| Easi3R ( Chen et al., 2025 ) | 54.93 | 68.00 | 45.29 | 47.30 | 54.75 | 66.16 | 44.09 | 42.36 | 51.64 | 63.06 | 40.98 | 38.49 |
| MonST3R ( Zhang et al., 2025 ) | 40.42 | 40.39 | 49.54 | 52.12 | 38.07 | 36.05 | 48.24 | 49.01 | 36.98 | 34.52 | 47.03 | 46.72 |
| DAS3R ( Xu et al., 2024a ) | 41.13 | 38.67 | 44.50 | 36.94 | 44.51 | 43.95 | 46.71 | 44.96 | 43.33 | 38.93 | 45.24 | 38.78 |
| VGGT4D ( Hu et al., 2026 ) | 62.12 | 76.80 | 56.04 | 67.49 | 56.45 | 65.62 | 51.09 | 56.85 | 50.75 | 55.59 | 47.04 | 46.43 |
| Variant | 1 | 2 | 4 | 8 | ||||||||
| PSNR | SSIM | LPIPS | PSNR | SSIM | LPIPS | PSNR | SSIM | LPIPS | PSNR | SSIM | LPIPS | |
| Baselines | ||||||||||||
| Static NVS model | 21.90 | 0.727 | 0.287 | 20.87 | 0.716 | 0.308 | 20.49 | 0.705 | 0.325 | 20.35 | 0.700 | 0.332 |
| Static NVS model, fine-tuned | 21.83 | 0.668 | 0.320 | 21.30 | 0.664 | 0.334 | 21.32 | 0.666 | 0.338 | 21.33 | 0.665 | 0.339 |
| Architecture | ||||||||||||
| Unfrozen renderer | 22.15 | 0.681 | 0.309 | 21.57 | 0.676 | 0.325 | 21.55 | 0.676 | 0.332 | 21.55 | 0.676 | 0.334 |
| Region | Feat. | 1 | 2 | 4 | 8 | 16 | |
| All | 27.33 | 5.65 | 12.43 | 25.37 | 39.78 | 53.40 | |
| 29.04 | 5.76 | 12.50 | 26.50 | 42.81 | 57.64 | ||
| ( 1.71) | ( 0.11) | ( 0.07) | ( 1.13) | ( 3.03) | ( 4.24) | ||
| Dyn | 23.45 | 3.10 | 9.12 | 21.14 | 34.84 | 49.03 | |
| 25.29 | 3.12 | 9.20 | 22.37 | 38.05 | 53.68 | ||
| ( 1.84) | ( 0.02) | ( 0.08) | ( 1.23) | ( 3.21) | ( 4.65) |
| Region | Feat. | 1 | 2 | 4 | 8 | ||||
| AbsRel | AbsRel | AbsRel | AbsRel | ||||||
| All | 0.1129 | 0.8550 | 0.1023 | 0.8729 | 0.0944 | 0.8908 | 0.0868 | 0.9081 | |
| 0.1037 | 0.8722 | 0.0932 | 0.8937 | 0.0863 | 0.9035 | 0.0751 | 0.9326 | ||
| ( 0.0092) | ( 0.0171) | ( 0.0092) | ( 0.0208) | ( 0.0081) | ( 0.0127) | ( 0.0117) | ( 0.0244) | ||
| Dyn | 0.1180 | 0.8597 | 0.1194 | 0.8614 | 0.1178 | 0.8699 | 0.1149 | 0.8790 | |
| 0.1127 | 0.8747 | 0.1078 | 0.8824 | 0.1050 | 0.8941 | 0.0996 | 0.9099 | ||
| Region | Feat. | 1 | 2 | 4 | 8 | ||||||||
| AJ | OA | AJ | OA | AJ | OA | AJ | OA | ||||||
| All | 37.63 | 52.35 | 70.40 | 36.15 | 51.65 | 69.20 | 33.10 | 49.00 | 66.42 | 28.92 | 45.82 | 63.42 | |
| 40.45 | 54.84 | 73.25 | 39.80 | 54.76 | 72.61 | 36.59 | 51.73 | 69.79 | 32.29 | 47.60 | 67.06 | ||
| ( 2.82) | ( 2.49) | ( 2.85) | ( 3.64) | ( 3.11) | ( 3.41) | ( 3.49) | ( 2.73) | ( 3.37) | ( 3.38) | ( 1.78) | ( 3.64) | ||
| Dyn | 32.26 | 47.85 | 66.12 | 30.83 | 47.39 | 64.80 | 28.57 | 45.69 | 62.65 | 24.84 | 42.88 | 59.72 | |
| 34.82 | 49.86 | 69.23 | 34.09 | 49.53 | 68.65 | 32.01 | 47.70 | 66.64 | 28.75 | 44.81 | 64.38 | ||
| Method | Alignment | ADT | TUM | ||||
| PSNR | SSIM | LPIPS | PSNR | SSIM | LPIPS | ||
| NeoVerse ( Yang et al., 2026 ) | ✗ | 12.217 | 0.2982 | 0.6391 | 14.398 | 0.4159 | 0.4587 |
| ✓ | 16.179 | 0.4384 | 0.5296 | 16.120 | 0.5266 | 0.3981 | |
| ( 3.962) | ( 0.1402) | ( 0.1095) | ( 1.721) | ( 0.1107) | ( 0.0606) | ||
| C4G ( Kim et al., 2026c ) | ✗ | 12.963 | 0.4487 | 0.6870 | 12.378 | 0.3935 | 0.5984 |
| ✓ | 18.900 | 0.5813 | 0.5833 | 17.508 | 0.5518 | 0.4951 | |
Dynamic Novel View Synthesis
Dynamic novel view synthesis creates time-consistent images or videos from unseen camera positions in scenes that change over time.
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