Research map / 3D vision / Gaussian splatting
4D Gaussian Splatting in the Wild with Uncertainty-Aware Regularization
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Proposes UA-4DGS, a 4D Gaussian Splatting method for casually captured monocular videos that uses uncertainty-weighted diffusion and depth-smoothness regularization plus dynamic-region densification, and also extends to few-shot static scenes (UA-3DGS).
Problem
4D Gaussian Splatting overfits training frames when reconstructing dynamic scenes from casually recorded, fast-motion monocular handheld videos, and SfM initialization leaves fast-moving dynamic regions without Gaussian primitives.
Approach
Estimate per-Gaussian uncertainty from accumulated blending contributions over training views, render a 2D uncertainty map for novel views, and apply diffusion-prior and depth-TV regularization weighted by this map so that well-observed regions are not over-smoothed; initialize extra Gaussians in dynamic regions from estimated depth and RGB.
Key results
- On DyCheck, UA-4DGS reaches 15.25 mPSNR, 0.488 mSSIM, 0.390 mLPIPS versus 14.14 / 0.465 / 0.430 for the 4DGS baseline.
- On the spin scene, the ablation shows mPSNR rising from 15.25 (4DGS) to 17.37 with the full method.
- On LLFF with three training views, UA-3DGS reaches 20.89 PSNR and 0.217 LPIPS, versus 19.82 and 0.238 for FSGS reproduced.
Measured effects reported in the paper
| What was changed | Where | Measured | Effect |
|---|---|---|---|
| add data-driven depth and flow losses (ablation) | 4DGS · DyCheck spin | mPSNR: 15.25 -> 15.74 | Helped |
| add dynamic region densification (ablation) | Ours + data-driven losses · DyCheck spin | mPSNR: 15.74 -> 17.04 | Helped |
| add uncertainty-aware diffusion loss (ablation) | Ours + data-driven losses + dynamic region densification · DyCheck spin | mPSNR: 17.04 -> 17.32 | Helped |
| add uncertainty-aware depth total variation loss (ablation) | Ours + data-driven losses + dynamic region densification + UA-diff · DyCheck spin | mPSNR: 17.32 -> 17.37 | Helped |
| use uncertainty-aware diffusion regularization instead of uniform diffusion regularization (ablation) | FSGS · LLFF room (train) | PSNR: 38.40 -> 41.28 | Helped |
| use uncertainty-aware diffusion regularization instead of uniform diffusion regularization (ablation) | FSGS · LLFF room (test) | PSNR: 20.40 -> 20.98 | Helped |
| use uncertainty-aware TV regularization instead of uniform TV regularization (ablation) | FSGS · LLFF room (train) | PSNR: 38.25 -> 38.26 | No clear effect |
| use uncertainty-aware TV regularization instead of uniform TV regularization (ablation) | FSGS · LLFF room (test) | PSNR: 20.77 -> 21.08 | Helped |
| use UA-4DGS instead of 4DGS | 4D Gaussian Splatting · DyCheck | mPSNR: 14.14 -> 15.25 | Helped |
| use UA-3DGS instead of FSGS | FSGS · LLFF (3 views) | PSNR: 19.82 -> 20.89 | Helped |
Surprising findings
- Gaussian-splatting methods fall behind MLP-based methods on the casual monocular DyCheck setting.
- Uniform diffusion and TV regularization degrade training-image reconstruction, while uncertainty-weighted versions preserve it.
Limitations
- Performance on casually recorded monocular videos still lags behind multi-view or simpler datasets.
- Regularization operates at the image level with 2D uncertainty maps rather than per-Gaussian.
- Dynamic region densification does not enforce temporal consistency in primitive initialization.
Experimental setup
Datasets: DyCheck LLFF
Benchmarks: DyCheck LLFF
Metrics: mPSNR mSSIM mLPIPS PSNR SSIM LPIPS FPS
Baselines: D-3DGS Zhan et al. 4DGS T-NeRF NSFF Nerfies HyperNeRF FSGS 3DGS DietNeRF RegNeRF FreeNeRF
Builds on: 4DGS (Wu et al. 4D Gaussian splatting with Hexplane) FSGS 3D Gaussian Splatting SDEdit DreamBooth
Closest papers by meaning
- Instant4D: 4D Gaussian Splatting in Minutes (NeurIPS 2025 · similarity 0.92)
- MoDGS: Dynamic Gaussian Splatting from Casually-captured Monocular Videos with Depth Priors (ICLR 2025 · similarity 0.92)
- KeyGS: A Keyframe-Centric Gaussian Splatting Method for Monocular Image Sequences (AAAI 2025 · similarity 0.91)
- Swift4D: Adaptive divide-and-conquer Gaussian Splatting for compact and efficient reconstruction of dynamic scene (ICLR 2025 · similarity 0.91)
- Orientation-anchored Hyper-Gaussian for 4D Reconstruction from Casual Videos (NeurIPS 2025 · similarity 0.91)
- Gaussian-Flow: 4D Reconstruction with Dynamic 3D Gaussian Particle (CVPR 2024 · similarity 0.91)
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