pith. sign in

arxiv: 2604.16976 · v1 · submitted 2026-04-18 · 💻 cs.CV · cs.GR

UGD: An Unsupervised Geometric Distance for Evaluating Real-world Noisy Point Cloud Denoising

Pith reviewed 2026-05-10 06:20 UTC · model grok-4.3

classification 💻 cs.CV cs.GR
keywords unsupervised evaluationpoint cloud denoisinggeometric distanceGaussian mixture modelself-supervised learningpatch-wise featuresreal-world noisy data
0
0 comments X

The pith

An unsupervised geometric distance evaluates point cloud denoising using only noisy input data.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper proposes an unsupervised geometric distance, UGD, that evaluates point cloud denoising methods without requiring clean ground-truth point clouds. It does this by learning a Gaussian Mixture Model as a reference from features of clean point cloud patches, where the features come from a network trained self-supervised on tasks like quality ranking and distortion prediction. The distance then measures how far the patches in a denoised cloud stray from this reference model. This matters for real-world use because clean references are rarely available for scanned data, so previous metrics could not be applied. If the method holds, it lets researchers assess and improve denoising algorithms using only the noisy data at hand.

Core claim

UGD is defined by first extracting patch-wise quality-aware features from clean point clouds with a network trained via self-supervised multi-task learning including pair-wise quality ranking, distortion classification, and distortion distribution prediction, fitting a pristine GMM to these features, and then computing the weighted sum of distances from each patch of the denoised point cloud to the GMM in feature space; this serves as the ground-truth proxy for quantifying denoising quality.

What carries the argument

The unsupervised geometric distance (UGD) computed as the weighted sum of distances from each denoised patch to a pristine GMM prior learned in the space of quality-aware patch features.

If this is right

  • On synthetic noise, UGD matches the performance of supervised metrics that use ground-truth.
  • On real-world noisy point clouds, UGD allows full unsupervised evaluation and comparison of denoising methods.
  • The approach relies only on the input noisy clouds for evaluation after the prior is learned.
  • Self-supervised multi-task training captures geometric degradation relevant to denoising.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • This could inspire similar unsupervised metrics for other 3D vision tasks like surface reconstruction where ground truth is hard to obtain.
  • If validated further, it might shift benchmarking practices away from synthetic datasets toward real noisy ones.
  • One possible extension is to update the GMM prior online as more clean data becomes available.

Load-bearing premise

The self-supervised features learned on clean clouds encode exactly the geometric properties that denoising is supposed to improve, so the GMM distance reliably indicates denoising success even without seeing the clean target.

What would settle it

Run denoising methods on a dataset of real noisy point clouds that also has hidden clean versions, then verify whether the ordering of methods by UGD scores agrees with their ordering by a supervised metric like Chamfer distance.

Figures

Figures reproduced from arXiv: 2604.16976 by Jincan Wu, Weiqing Li, Yonghui Liu, Zheng Li, Zhiyong Su.

Figure 1
Figure 1. Figure 1: Overview of the proposed unsupervised geometric distance (UGD) approach. It comprises Offline Patch-wise Prior Modeling (top), which learns a GMM prior from clean patch features, and Online UGD Computation (bottom), which quantifies degradation by calculating the weighted Mahalanobis distance between patches of denoised point cloud and the learned prior. which serves as the ground-truth in the offline phas… view at source ↗
Figure 2
Figure 2. Figure 2: Snapshots of some point clouds in the ideal clean point cloud dataset D. random sampling strategy is employed to obtain the Cartesian coordinates of the generated point cloud from the mesh surfaces. 2) Patch-wise Feature Learning: The patch-wise feature learning is designed to partition input point clouds into overlapped patches, and then learn patch-wise geometric quality-aware features for each patch thr… view at source ↗
Figure 3
Figure 3. Figure 3: Overview of the Self-Supervised Multi-Task (SSMT) training framework. It integrates Distortion Augmentation (generating diverse noise samples), Weighted Feature Learning (extracting adaptive patch features), and Multi-Task Training (Ranking, Classification, and Prediction tasks) to learn robust geometric quality-aware representations. quality scores of colored point clouds. Therefore, it is difficult to em… view at source ↗
Figure 4
Figure 4. Figure 4: Visualization of results of the proposed UGD, the point-to-point (po2po) [34] metric, and the Chamfer Distance (CD) [10]. levels. Specifically, each testing ground-truth clean point cloud in D is firstly corrupted with four basic noises (i.e., Gaussian noise, uniform noise, exponential noise, impulse noise with ξ ∈ [0.05, 0.1, 0.15, 0.2]) and mixed noise, respectively. Subsequently, for each type of noise,… view at source ↗
Figure 5
Figure 5. Figure 5: Visualization of structural complexity of the first and eleventh testing point clouds. with smoother surfaces typically exhibit less geometric distortion, resulting in higher UGD in the unsupervised quality evaluation. In contrast, point clouds with complex geometric structure tend to have lower UGD due to their intricate geometric and detail distortions. Therefore, the proposed UGD reflects not only the q… view at source ↗
Figure 6
Figure 6. Figure 6: Visualization of denoising results of selected testing point clouds associated with evaluation metrics. Window PF UGD: 154.31 Car low PF UGD: 143.59 table PF UGD: 51.90 PD-LTS UGD: 162.19 PD-LTS UGD: 139.42 PD-LTS UGD: 82.96 IterativePFN UGD: 167.09 IterativePFN UGD: 149.01 IterativePFN UGD: 154.09 [PITH_FULL_IMAGE:figures/full_fig_p011_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: Visualization of denoising results of selected denoising algorithms on real-world noisy point clouds.More visualization results can be found in the supplementary material. TABLE II Impact of weight parameters on the ranking performance of UGD (%) GN EN IN UN MN MEAN α (1,0,0,0) (0,1,0,0) (0,0,1,0) (0,0,0,1) (0.5,0.5,0,0) (0.33,0.33,0.33,0) (0.25,0.25,0.25,0.25) UGD (with weight parameters) 100.00 98.89 99.… view at source ↗
Figure 8
Figure 8. Figure 8: Visualization of the gradient normalization in multi-task training. Although the accuracy of the pair-wise ranking task is already relatively high, the multi-task training approach integrates the learning objectives of multiple subtasks, further enhancing overall performance [PITH_FULL_IMAGE:figures/full_fig_p012_8.png] view at source ↗
read the original abstract

Point cloud denoising is a fundamental and crucial challenge in real-world point cloud applications. Existing quantitative evaluation metrics for point cloud denoising methods are implemented in a supervised manner, which requires both the denoised point cloud and the corresponding ground-truth clean point cloud to compute a representative geometric distance. This requirement is highly problematic in real-world scenarios, where ground-truth clean point clouds are often unavailable. In this paper, we propose a simple yet effective unsupervised geometric distance (UGD) for real-world noisy point cloud denoising, calculated solely from noisy point clouds. The core idea of UGD is to learn a patch-wise prior model from a set of clean point clouds and then employ this prior model as the ground-truth to quantify the degradation by measuring the geometric variations of the denoised point cloud. To this end, we first learn a pristine Gaussian Mixture Model (GMM) with extracted patch-wise quality-aware features from a set of pristine clean point clouds by a patch-wise feature extraction network, which serves as the ground-truth for the quantitative evaluation. Then, the UGD is defined as the weighted sum of distances between each patch of the denoised point cloud and the learned pristine GMM model in the patch space. To train the employed patch-wise feature extraction network, we propose a self-supervised training framework through multi-task learning, which includes pair-wise quality ranking, distortion classification, and distortion distribution prediction. Quantitative experiments with synthetic noise confirm that the proposed UGD achieves comparable performance to supervised full-reference metrics. Moreover, experimental results on real-world data demonstrate that the proposed UGD enables unsupervised evaluation of point cloud denoising methods based exclusively on noisy point clouds.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 1 minor

Summary. The paper proposes UGD, an unsupervised geometric distance for evaluating point cloud denoising without ground-truth clean references. It trains a patch-wise feature extractor via self-supervised multi-task learning (quality ranking, distortion classification, distribution prediction) exclusively on clean point clouds with synthetic distortions, fits a GMM to the resulting features as a pristine prior, and defines UGD as the weighted sum of distances from patches of a denoised cloud to this GMM.

Significance. If the learned features and GMM reliably proxy geometric quality under real sensor noise, UGD would enable quantitative, reference-free evaluation of denoising algorithms on real-world data, addressing a practical limitation where paired clean point clouds are unavailable.

major comments (2)
  1. [Abstract] The real-world claim (abstract) that UGD enables unsupervised evaluation based exclusively on noisy point clouds rests on the untested assumption that patch features learned from clean data with synthetic distortions remain sensitive to the specific geometric degradations introduced by real denoising methods on real sensor noise; no cross-domain ablation, human correlation study, or mapping of feature distances to surface error is provided to support transfer.
  2. [Abstract] The synthetic-noise claim that UGD achieves comparable performance to supervised full-reference metrics lacks any reported quantitative values, baselines, statistical tests, or error analysis, preventing assessment of whether the comparability is meaningful or merely incidental.
minor comments (1)
  1. The abstract would be strengthened by including at least one key quantitative result (e.g., correlation coefficient or rank correlation with a supervised metric) to ground the comparability claim.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive comments on our manuscript. We address each major comment point by point below, providing clarifications and committing to revisions where they strengthen the paper without misrepresenting our contributions.

read point-by-point responses
  1. Referee: [Abstract] The real-world claim (abstract) that UGD enables unsupervised evaluation based exclusively on noisy point clouds rests on the untested assumption that patch features learned from clean data with synthetic distortions remain sensitive to the specific geometric degradations introduced by real denoising methods on real sensor noise; no cross-domain ablation, human correlation study, or mapping of feature distances to surface error is provided to support transfer.

    Authors: We acknowledge that the manuscript does not include explicit cross-domain ablations, human correlation studies, or direct mappings from feature distances to surface error metrics to validate transfer from synthetic training to real sensor noise. The self-supervised multi-task framework (quality ranking, distortion classification, and distribution prediction) is designed to capture general geometric degradation cues rather than noise-specific patterns, and the real-world experiments demonstrate that UGD produces rankings consistent with expected improvements from denoising algorithms. To address the concern, we will add a dedicated discussion subsection on the domain-transfer assumptions, limitations, and rationale for generalization. We will also include a preliminary analysis mapping UGD values to approximate geometric errors on available synthetic proxies where feasible. revision: partial

  2. Referee: [Abstract] The synthetic-noise claim that UGD achieves comparable performance to supervised full-reference metrics lacks any reported quantitative values, baselines, statistical tests, or error analysis, preventing assessment of whether the comparability is meaningful or merely incidental.

    Authors: The abstract summarizes the key finding, while the full manuscript (Section 4) reports detailed quantitative comparisons on synthetic datasets, including tables with correlation coefficients to full-reference metrics (e.g., Chamfer Distance, Earth Mover's Distance), performance across noise levels, and baseline methods. To improve accessibility and allow immediate assessment of the claim, we will revise the abstract to incorporate specific quantitative indicators such as average Spearman correlation values and mention of the statistical comparisons performed. revision: yes

Circularity Check

0 steps flagged

No circularity: UGD is defined via independent clean-data prior, not by construction on evaluation inputs

full rationale

The paper defines UGD by first training a patch-wise feature extractor on separate clean point clouds via self-supervised multi-task learning (quality ranking, distortion classification, distribution prediction), fitting a GMM in that feature space as a pristine reference, and then computing weighted distances of denoised patches to this fixed GMM. This construction uses an external clean dataset and does not reduce the metric for any test denoised cloud to a fit, self-definition, or tautology based on the evaluation data itself. No self-citations, uniqueness theorems, or ansatzes are invoked to force the result; the derivation chain remains independent of the real-world noisy inputs being evaluated.

Axiom & Free-Parameter Ledger

3 free parameters · 1 axioms · 1 invented entities

The central claim rests on the validity of the learned prior model and the self-supervised feature learning capturing relevant geometric quality aspects. Since only the abstract is available, specific values and additional assumptions cannot be detailed.

free parameters (3)
  • GMM parameters
    Learned from clean point cloud patches to model pristine distribution.
  • feature extraction network weights
    Trained via self-supervised multi-task learning.
  • weights for distance sum
    Used to combine patch distances in UGD calculation.
axioms (1)
  • domain assumption Patch-wise features from clean point clouds can serve as a proxy for ground-truth quality in denoising evaluation.
    Central to using the GMM as reference without actual ground truth for the test data.
invented entities (1)
  • UGD (Unsupervised Geometric Distance) no independent evidence
    purpose: To quantify denoising degradation using only noisy inputs.
    Newly proposed metric defined in terms of the learned GMM.

pith-pipeline@v0.9.0 · 5611 in / 1563 out tokens · 61646 ms · 2026-05-10T06:20:25.403048+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

69 extracted references · 69 canonical work pages

  1. [1]

    Con- trastive learning for joint normal estimation and point cloud filtering,

    D. de Silva Edirimuni, X. Lu, G. Li, and A. Robles-Kelly, “Con- trastive learning for joint normal estimation and point cloud filtering,” IEEE Transactions on Visualization and Computer Graphics, vol. 30, no. 8, pp. 4527–4541, 2024

  2. [2]

    Pathnet: Path-selective point cloud denoising,

    Z. Wei, H. Chen, L. Nan, J. Wang, J. Qin, and M. Wei, “Pathnet: Path-selective point cloud denoising,” IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. 46, no. 6, pp. 4426–4442, 2024

  3. [3]

    Total denoising: Unsupervised learning of 3d point cloud cleaning,

    P. Hermosilla, T. Ritschel, and T. Ropinski, “Total denoising: Unsupervised learning of 3d point cloud cleaning,” in Proceed- ings of the IEEE/CVF International Conference on Computer Vision, 2019, pp. 52–60

  4. [4]

    Sitf: A self-supervised iterative training framework for point cloud denoising,

    Z. Su, C. Wang, K. Jiang, K. Jiang, and W. Li, “Sitf: A self-supervised iterative training framework for point cloud denoising,” Computer-Aided Design, vol. 179, p. 103812, 2025

  5. [5]

    Point cloud denois- ing review: from classical to deep learning-based approaches,

    L. Zhou, G. Sun, Y. Li, W. Li, and Z. Su, “Point cloud denois- ing review: from classical to deep learning-based approaches,” Graphical Models, vol. 121, p. 101140, 2022

  6. [6]

    A gener- alized hausdorff distance based quality metric for point cloud JOURNAL OF LATEX CLASS FILES, VOL. 14, NO. 8, AUGUST 2021 13 geometry,

    A. Javaheri, C. Brites, F. Pereira, and J. Ascenso, “A gener- alized hausdorff distance based quality metric for point cloud JOURNAL OF LATEX CLASS FILES, VOL. 14, NO. 8, AUGUST 2021 13 geometry,” in 2020 Twelfth International Conference on Quality of Multimedia Experience, 2020, pp. 1–6

  7. [7]

    A comparison of perceptually-based metrics for objective evaluation of geometry processing,

    G. Lavoué and M. Corsini, “A comparison of perceptually-based metrics for objective evaluation of geometry processing,” IEEE Transactions on Multimedia, vol. 12, no. 7, pp. 636–649, 2010

  8. [8]

    Geometric distortion metrics for point cloud compression,

    D. Tian, H. Ochimizu, C. Feng, R. Cohen, and A. Vetro, “Geometric distortion metrics for point cloud compression,” in 2017 IEEE International Conference on Image Processing, 2017, pp. 3460–3464

  9. [9]

    A survey of denoising techniques for multi-parametric prostate mri,

    G. Garg and M. Juneja, “A survey of denoising techniques for multi-parametric prostate mri,” Multimedia Tools and Appli- cations, vol. 78, pp. 12 689–12 722, 2019

  10. [10]

    Pointfilter: Point cloud filtering via encoder-decoder modeling,

    D. Zhang, X. Lu, H. Qin, and Y. He, “Pointfilter: Point cloud filtering via encoder-decoder modeling,” IEEE Transactions on Visualization and Computer Graphics, vol. 27, no. 3, pp. 2015– 2027, 2020

  11. [11]

    Eval- uating unsupervised denoising requires unsupervised metrics,

    A. Marcos-Morales, M. Leibovich, S. Mohan, J. L. Vincent, P. Haluai, M. Tan, P. Crozier, and C. Fernandez-Granda, “Eval- uating unsupervised denoising requires unsupervised metrics,” in Proceedings of the 40th International Conference on Machine Learning, 2023, pp. 23 937–23 957

  12. [12]

    Perceptual quality assessment for point clouds: A survey,

    Y. Zhou, Z. Zhang, W. Sun, X. Min, and G. Zhai, “Perceptual quality assessment for point clouds: A survey,” ZTE Commu- nications, vol. 21, no. 4, pp. 3–16, 12 2023

  13. [13]

    Pqa-net: Deep no reference point cloud quality assessment via multi-view projection,

    Q. Liu, H. Yuan, H. Su, H. Liu, Y. Wang, H. Yang, and J. Hou, “Pqa-net: Deep no reference point cloud quality assessment via multi-view projection,” IEEE Transactions on Circuits and Systems for Video Technology, vol. 31, no. 12, pp. 4645–4660, 2021

  14. [14]

    Contrastive Pre-Training with Multi-View Fusion for No-Reference Point Cloud Quality Assessment ,

    Z. Shan, Y. Zhang, Q. Yang, H. Yang, Y. Xu, J.-N. Hwang, X. Xu, and S. Liu, “ Contrastive Pre-Training with Multi-View Fusion for No-Reference Point Cloud Quality Assessment ,” in 2024 IEEE/CVF Conference on Computer Vision and Pattern Recognition, 2024, pp. 25 942–25 951

  15. [15]

    Forest point cloud denoising method based on curvature and density,

    Q. Feng, T. Zhu, and C. Ni, “Forest point cloud denoising method based on curvature and density,” International Journal of Remote Sensing, vol. 45, no. 22, pp. 8105–8122, 2024

  16. [16]

    Learning implicit fields for point cloud filtering,

    J. Wang, X. Lu, M. Wang, F. Hou, and Y. He, “Learning implicit fields for point cloud filtering,” IEEE Transactions on Visualization and Computer Graphics, vol. 31, no. 9, pp. 5408– 5420, 2025

  17. [17]

    StraightPCF: Straight Point Cloud Filtering,

    D. de Silva Edirimuni, X. Lu, G. Li, L. Wei, A. Robles-Kelly, and H. Li, “StraightPCF: Straight Point Cloud Filtering,” in 2024 IEEE/CVF Conference on Computer Vision and Pattern Recognition, 2024, pp. 20 721–20 730

  18. [18]

    Iterativepfn: True iterative point cloud filtering,

    D. de Silva Edirimuni, X. Lu, Z. Shao, G. Li, A. Robles-Kelly, and Y. He, “Iterativepfn: True iterative point cloud filtering,” in 2023 IEEE/CVF Conference on Computer Vision and Pattern Recognition, 2023, pp. 13 530–13 539

  19. [19]

    Computing and rendering point set surfaces,

    M. Alexa, J. Behr, D. Cohen-Or, S. Fleishman, D. Levin, and C. Silva, “Computing and rendering point set surfaces,” IEEE Transactions on Visualization and Computer Graphics, vol. 9, no. 1, pp. 3–15, 2003

  20. [20]

    Robust moving least-squares fitting with sharp features,

    S. Fleishman, D. Cohen-Or, and C. T. Silva, “Robust moving least-squares fitting with sharp features,” ACM Transactions on Graphics, vol. 24, no. 3, pp. 544–552, 2005

  21. [21]

    Feature preserv- ing point set surfaces based on non-linear kernel regression,

    C. Oztireli, G. Guennebaud, and M. Gross, “Feature preserv- ing point set surfaces based on non-linear kernel regression,” Computer Graphics Forum, vol. 28, no. 2, pp. 493–501, 2009

  22. [22]

    Parameterization-free projection for geometry reconstruction,

    Y. Lipman, D. Cohen-Or, D. Levin, and H. Tal-Ezer, “Parameterization-free projection for geometry reconstruction,” ACM Transactions on Graphics, vol. 26, no. 3, p. 22, 2007

  23. [23]

    Consolidation of unorganized point clouds for surface recon- struction,

    H. Huang, D. Li, H. Zhang, U. Ascher, and D. Cohen-Or, “Consolidation of unorganized point clouds for surface recon- struction,” ACM Transactions on Graphics, vol. 28, no. 5, pp. 1–7, 2009

  24. [24]

    Continuous projection for fast l1 reconstruction,

    R. Preiner, O. Mattausch, M. Arikan, R. Pajarola, and M. Wim- mer, “Continuous projection for fast l1 reconstruction,” ACM Transactions on Graphics, vol. 33, pp. 1–13, 2014

  25. [25]

    Pcpnet learning local shape properties from raw point clouds,

    P. Guerrero, Y. Kleiman, M. Ovsjanikov, and N. J. Mitra, “Pcpnet learning local shape properties from raw point clouds,” Computer Graphics Forum, vol. 37, no. 2, pp. 75–85, 2018

  26. [26]

    Pointcleannet: Learning to denoise and remove outliers from dense point clouds,

    M.-J. Rakotosaona, V. La Barbera, P. Guerrero, N. J. Mitra, and M. Ovsjanikov, “Pointcleannet: Learning to denoise and remove outliers from dense point clouds,” Computer Graphics Forum, vol. 39, no. 1, pp. 185–203, 2020

  27. [27]

    Modnet: Multi-offset point cloud denoising network customized for multi-scale patches,

    A. Huang, Q. Xie, Z. Wang, D. Lu, M. Wei, and J. Wang, “Modnet: Multi-offset point cloud denoising network customized for multi-scale patches,” Computer Graphics Forum, vol. 41, pp. 109–119, 2023

  28. [28]

    Geodualcnn: Geometry-supporting dual convolutional neural network for noisy point clouds,

    M. Wei, H. Chen, Y. Zhang, H. Xie, Y. Guo, and J. Wang, “Geodualcnn: Geometry-supporting dual convolutional neural network for noisy point clouds,” IEEE Transactions on Visual- ization and Computer Graphics, vol. 29, no. 2, pp. 1357–1370, 2023

  29. [29]

    Score-based point cloud denoising,

    S. Luo and W. Hu, “Score-based point cloud denoising,” in 2021 IEEE/CVF International Conference on Computer Vision, 2021, pp. 4563–4572

  30. [30]

    Pd-flow: A point cloud denoising framework with normalizing flows,

    A. Mao, Z. Du, Y.-H. Wen, J. Xuan, and Y.-J. Liu, “Pd-flow: A point cloud denoising framework with normalizing flows,” in The European Conference on Computer Vision, 2022, pp. 398– 415

  31. [31]

    Denoising point clouds in latent space via graph convolution and invertible neural network,

    A. Mao, B. Yan, Z. Ma, and Y. He, “Denoising point clouds in latent space via graph convolution and invertible neural network,” in 2024 IEEE/CVF Conference on Computer Vision and Pattern Recognition, 2024, pp. 5768–5777

  32. [32]

    Differentiable manifold reconstruction for point cloud denoising,

    S. Luo and W. Hu, “Differentiable manifold reconstruction for point cloud denoising,” in Proceedings of the 28th ACM International Conference on Multimedia, 2020, pp. 1330–1338

  33. [33]

    Noise4denoise: Leveraging noise for unsupervised point cloud denoising,

    W. Wang, X. Liu, H. Zhou, L. Wei, Z. Deng, M. Murshed, and X. Lu, “Noise4denoise: Leveraging noise for unsupervised point cloud denoising,” Computational Visual Media, vol. 10, no. 4, pp. 659–669, 2024

  34. [34]

    Evaluation criteria for pcc (point cloud compression),

    R. Mekuria, Z. Li, C. Tulvan, and P. A. Chou, “Evaluation criteria for pcc (point cloud compression),” ISO/IEC MPEG N16332, 2016

  35. [35]

    Point cloud quality assessment metric based on angular similarity,

    E. Alexiou and T. Ebrahimi, “Point cloud quality assessment metric based on angular similarity,” in 2018 IEEE International Conference on Multimedia and Expo, 2018, pp. 1–6

  36. [36]

    Subjective and objective quality evaluation of 3d point cloud denoising algorithms,

    A. Javaheri, C. Brites, F. Pereira, and J. Ascenso, “Subjective and objective quality evaluation of 3d point cloud denoising algorithms,” in 2017 IEEE International Conference on Multi- media & Expo Workshops, 2017, pp. 1–6

  37. [37]

    Metro: Measuring error on simplified surfaces,

    P. Cignoni, C. Rocchini, and R. Scopigno, “Metro: Measuring error on simplified surfaces,” Computer Graphics Forum, vol. 17, pp. 167–174, 1998

  38. [38]

    Subjective quality database and objective study of compressed point clouds with 6dof head-mounted display,

    X. Wu, Y. Zhang, C. Fan, J. Hou, and S. Kwong, “Subjective quality database and objective study of compressed point clouds with 6dof head-mounted display,” IEEE Transactions on Cir- cuits and Systems for Video Technology, vol. 31, no. 12, pp. 4630–4644, 2021

  39. [39]

    Benchmarking of objective quality metrics for colorless point clouds,

    E. Alexiou and T. Ebrahimi, “Benchmarking of objective quality metrics for colorless point clouds,” in 2018 Picture Coding Symposium, 2018, pp. 51–55

  40. [40]

    Inferring point cloud quality via graph similarity,

    Q. Yang, Z. Ma, Y. Xu, Z. Li, and J. Sun, “Inferring point cloud quality via graph similarity,” IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. 44, no. 6, pp. 3015–3029, 2022

  41. [41]

    Perceptual quality assessment of colored 3d point clouds,

    Q. Liu, H. Su, Z. Duanmu, W. Liu, and Z. Wang, “Perceptual quality assessment of colored 3d point clouds,” IEEE Transac- tions on Visualization and Computer Graphics, vol. 29, no. 8, pp. 3642–3655, 2023

  42. [42]

    Tcdm: Transformational complexity based distortion metric for perceptual point cloud quality assessment,

    Y. Zhang, Q. Yang, Y. Zhou, X. Xu, L. Yang, and Y. Xu, “Tcdm: Transformational complexity based distortion metric for perceptual point cloud quality assessment,” IEEE Transactions on Visualization and Computer Graphics, vol. 30, no. 10, pp. 6707–6724, 2024

  43. [43]

    Perception-guided quality metric of 3d point clouds using hybrid strategy,

    Y. Zhang, Q. Yang, Y. Xu, and S. Liu, “Perception-guided quality metric of 3d point clouds using hybrid strategy,” IEEE Transactions on Image Processing, vol. 33, pp. 5755–5770, 2024

  44. [44]

    A reduced reference metric for visual quality evaluation of point cloud contents,

    I. Viola and P. Cesar, “A reduced reference metric for visual quality evaluation of point cloud contents,” IEEE Signal Pro- cessing Letters, vol. 27, pp. 1660–1664, 2020

  45. [45]

    Reduced- reference quality assessment of point clouds via content-oriented saliency projection,

    W. Zhou, G. Yue, R. Zhang, Y. Qin, and H. Liu, “Reduced- reference quality assessment of point clouds via content-oriented saliency projection,” IEEE Signal Processing Letters, vol. 30, pp. 354–358, 2023

  46. [46]

    No-reference point cloud quality assessment via domain adaptation,

    Q. Yang, Y. Liu, S. Chen, Y. Xu, and J. Sun, “No-reference point cloud quality assessment via domain adaptation,” in Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition, 2022, pp. 21 179–21 188

  47. [47]

    Gms-3dqa: Projection-based grid mini- JOURNAL OF LATEX CLASS FILES, VOL. 14, NO. 8, AUGUST 2021 14 patch sampling for 3d model quality assessment,

    Z. Zhang, W. Sun, H. Wu, Y. Zhou, C. Li, Z. Chen, X. Min, G. Zhai, and W. Lin, “Gms-3dqa: Projection-based grid mini- JOURNAL OF LATEX CLASS FILES, VOL. 14, NO. 8, AUGUST 2021 14 patch sampling for 3d model quality assessment,” ACM Trans- actions on Multimedia Computing Communications and Appli- cations, vol. 20, no. 6, 2024

  48. [48]

    Point cloud quality as- sessment: Dataset construction and learning-based no-reference metric,

    Y. Liu, Q. Yang, Y. Xu, and L. Yang, “Point cloud quality as- sessment: Dataset construction and learning-based no-reference metric,” ACM Transactions on Multimedia Computing Com- munications and Applications, vol. 19, no. 2s, 2023

  49. [49]

    Gpa-net: No-reference point cloud quality assessment with multi-task graph convolutional network,

    Z. Shan, Q. Yang, R. Ye, Y. Zhang, Y. Xu, X. Xu, and S. Liu, “Gpa-net: No-reference point cloud quality assessment with multi-task graph convolutional network,” IEEE Transactions on Visualization and Computer Graphics, vol. 30, no. 8, pp. 4955–4967, 2024

  50. [50]

    3dta: No-reference 3d point cloud quality assess- ment with twin attention,

    L. Zhu, J. Cheng, X. Wang, H. Su, H. Yang, H. Yuan, and J. Korhonen, “3dta: No-reference 3d point cloud quality assess- ment with twin attention,” IEEE Transactions on Multimedia, vol. 26, pp. 10 489–10 502, 2024

  51. [51]

    Zippered polygon meshes from range images,

    G. Turk and M. Levoy, “Zippered polygon meshes from range images,” in Proceedings of the 21st Annual Conference on Computer Graphics and Interactive Techniques, 1994, pp. 311– 318

  52. [52]

    3d shapenets: A deep representation for volumetric shapes,

    Z. Wu, S. Song, A. Khosla, F. Yu, L. Zhang, X. Tang, and J. Xiao, “3d shapenets: A deep representation for volumetric shapes,” in 2015 IEEE Conference on Computer Vision and Pattern Recognition, 2015, pp. 1912–1920

  53. [53]

    Pointnet++: Deep hierarchical feature learning on point sets in a metric space,

    C. R. Qi, L. Yi, H. Su, and L. J. Guibas, “Pointnet++: Deep hierarchical feature learning on point sets in a metric space,” in Proceedings of the 31th International Conference on Neural Information Processing Systems, 2017, pp. 5099–5108

  54. [54]

    Pct: Point cloud transformer,

    M.-H. Guo, J.-X. Cai, Z.-N. Liu, T.-J. Mu, R. R. Martin, and S.- M. Hu, “Pct: Point cloud transformer,” Computational Visual Media, vol. 7, pp. 187–199, 2021

  55. [55]

    Maximum likelihood from incomplete data via the em algorithm,

    A. P. Dempster, N. M. Laird, and D. B. Rubin, “Maximum likelihood from incomplete data via the em algorithm,” Journal of the Royal Statistical Society. Series B (Methodological), vol. 39, no. 1, pp. 1–22, 1977

  56. [56]

    Predict- ing the perceptual quality of point cloud: A 3d-to-2d projection- based exploration,

    Q. Yang, H. Chen, Z. Ma, Y. Xu, R. Tang, and J. Sun, “Predict- ing the perceptual quality of point cloud: A 3d-to-2d projection- based exploration,” IEEE Transactions on Multimedia, vol. 23, pp. 3877–3891, 2021

  57. [57]

    Perceptual quality assessment of 3d point clouds,

    H. Su, Z. Duanmu, W. Liu, Q. Liu, and Z. Wang, “Perceptual quality assessment of 3d point clouds,” in 2019 IEEE Interna- tional Conference on Image Processing, 2019, pp. 3182–3186

  58. [58]

    Reduced reference perceptual quality model with application to rate control for video-based point cloud compression,

    Q. Liu, H. Yuan, R. Hamzaoui, H. Su, J. Hou, and H. Yang, “Reduced reference perceptual quality model with application to rate control for video-based point cloud compression,” IEEE Transactions on Image Processing, vol. 30, pp. 6623–6636, 2021

  59. [59]

    No- reference bitstream-layer model for perceptual quality assess- ment of v-pcc encoded point clouds,

    Q. Liu, H. Su, T. Chen, H. Yuan, and R. Hamzaoui, “No- reference bitstream-layer model for perceptual quality assess- ment of v-pcc encoded point clouds,” IEEE Transactions on Multimedia, vol. 25, pp. 4533–4546, 2022

  60. [60]

    Learning to rank using gradi- ent descent,

    C. Burges, T. Shaked, E. Renshaw, A. Lazier, M. Deeds, N. Hamilton, and G. Hullender, “Learning to rank using gradi- ent descent,” in Proceedings of the 22nd international conference on Machine learning, 2005, pp. 89–96

  61. [61]

    dipiq: Blind image quality assessment by learning-to-rank discriminable image pairs,

    K. Ma, W. Liu, T. Liu, Z. Wang, and D. Tao, “dipiq: Blind image quality assessment by learning-to-rank discriminable image pairs,” IEEE Transactions on Image Processing, vol. 26, no. 8, pp. 3951–3964, 2017

  62. [62]

    Rankiqa: Learn- ing from rankings for no-reference image quality assessment,

    X. Liu, J. Van De Weijer, and A. D. Bagdanov, “Rankiqa: Learn- ing from rankings for no-reference image quality assessment,” in Proceedings of the IEEE International Conference on Computer Vision, 2017, pp. 1040–1049

  63. [63]

    Pairwise-comparison- based rank learning for benchmarking image restoration algo- rithms,

    B. Hu, L. Li, H. Liu, W. Lin, and J. Qian, “Pairwise-comparison- based rank learning for benchmarking image restoration algo- rithms,” IEEE Transactions on Multimedia, vol. 21, no. 8, pp. 2042–2056, 2019

  64. [64]

    Gradnorm: Gradient normalization for adaptive loss balancing in deep multitask networks,

    Z. Chen, V. Badrinarayanan, C.-Y. Lee, and A. Rabinovich, “Gradnorm: Gradient normalization for adaptive loss balancing in deep multitask networks,” in International Conference on Machine Learning, 2018, pp. 794–803

  65. [65]

    Towards subjective quality assessment of point cloud imaging in augmented reality,

    E. Alexiou, E. Upenik, and T. Ebrahimi, “Towards subjective quality assessment of point cloud imaging in augmented reality,” in 2017 IEEE 19th International Workshop on Multimedia Signal Processing (MMSP), 2017, pp. 1–6

  66. [66]

    Lidar-net: A real-scanned 3d point cloud dataset for indoor scenes,

    Y. Guo, Y. Li, D. Ren, X. Zhang, J. Li, L. Pu, C. Ma, X. Zhan, J. Guo, M. Wei, Y. Zhang, P. Yu, S. Yang, D. Ji, H. Ye, H. Sun, Y. Liu, Y. Chen, J. Zhu, and H. Liu, “Lidar-net: A real-scanned 3d point cloud dataset for indoor scenes,” in 2024 IEEE/CVF Conference on Computer Vision and Pattern Recognition, 2024, pp. 21 989–21 999

  67. [67]

    Terramobilita/iqmulus urban point cloud analysis benchmark,

    B. Vallet, M. Brédif, A. Serna, B. Marcotegui, and N. Pa- paroditis, “Terramobilita/iqmulus urban point cloud analysis benchmark,” Computers & Graphics, vol. 49, pp. 126–133, 2015

  68. [68]

    Dynamic graph cnn for learning on point clouds,

    Y. Wang, Y. Sun, Z. Liu, S. E. Sarma, M. M. Bronstein, and J. M. Solomon, “Dynamic graph cnn for learning on point clouds,” ACM Transactions on Graphics, vol. 38, no. 5, 2019. Zhiyong Su is currently an associate professor at the School of Automation, Nanjing Uni- versity of Science and Technology, China. He received the B.S. and M.S. degrees from the Sch...

  69. [69]

    Jincan Wu received the B.S

    His current interests include computer graphics, computer vision, augmented reality, and machine learning. Jincan Wu received the B.S. degree from Nanjing University of Science and Technology, Jiangsu, China in 2023 and now studies at Nanjing University of Science and Technology. His research interests include mesh quality assessment and 3DGS quality asse...