Deep Unrolled Graph Laplacian Regularization for Robust Time-of-Flight Depth Denoising
Bibliographic record
Abstract
Depth images captured by Time-of-Flight (ToF) sensors are subject to severe noise. Recent approaches based on deep neural networks achieve good depth denoising performance in synthetic data, but the application to real-world data is limited, due to the complexity of actual depth noise characteristics and the difficulty in acquiring ground truth. In this paper, we propose a novel ToF depth denoising network based on unrolled graph Laplacian regularization to “robustify” the network against both noise complexity and dataset deficiency. Unlike previous schemes that are ignorant of underlying ToF imaging mechanism, we formulate a fidelity term in the optimization problem to adapt to the depth probabilistic distribution with spatially-varying noise variance. Then, we add quadratic graph Laplacian regularization as the smoothness prior, leading to a maximum a posteriori problem that is optimized efficiently by solving a linear system of equations. We unroll the solution into iterative filters so that parameters used in the optimization and graph construction are amendable to data-driven tuning. Because the resulting network is built using domain knowledge of ToF imaging principle and graph prior, it is robust against overfitting to synthetic training data. Experimental results demonstrate that the proposal outperforms existing schemes in ToF depth denoising on synthetic FLAT dataset and generalizes well to real Kinectv2 dataset.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".