Quartet of Diffusions: Structure-Aware Point Cloud Generation through Part and Symmetry Guidance
Chenliang Zhou, Fangcheng Zhong, Weihao Xia, Albert Miao, Canberk Baykal, Cengiz Oztireli

TL;DR
The paper presents Quartet of Diffusions, a novel structure-aware point cloud generation framework that models shape parts and symmetry explicitly, enabling high-quality, controllable 3D shape synthesis with guaranteed symmetry and coherence.
Contribution
It introduces a four-model diffusion pipeline that explicitly encodes shape parts, symmetry, and global structure, a first in fully integrating these priors in 3D point cloud generation.
Findings
Achieves state-of-the-art performance in point cloud generation.
Ensures guaranteed symmetry and coherent part placement.
Supports fine-grained control over shape attributes.
Abstract
We introduce the Quartet of Diffusions, a structure-aware point cloud generation framework that explicitly models part composition and symmetry. Unlike prior methods that treat shape generation as a holistic process or only support part composition, our approach leverages four coordinated diffusion models to learn distributions of global shape latents, symmetries, semantic parts, and their spatial assembly. This structured pipeline ensures guaranteed symmetry, coherent part placement, and diverse, high-quality outputs. By disentangling the generative process into interpretable components, our method supports fine-grained control over shape attributes, enabling targeted manipulation of individual parts while preserving global consistency. A central global latent further reinforces structural coherence across assembled parts. Our experiments show that the Quartet achieves state-of-the-art…
Peer Reviews
Decision·ICLR 2026 Poster
1. The paper proposed a novel symmetry conditioned point-cloud generation method. The symmetry diffusion formulation proposed in the paper seems novel and could potentially be a contribution to the shape generation field 2. The generation quality surpasses many strong baseline including LION and ShapeGF. This suggests the overall generation quality.
1. I found the application provided by the authors to be insufficient to justify the modeling of parts and symmetry. Part-level generation is not a novel task and could be done without modeling the symmetry (See DiffFacto). It would be great to see further application enabled by the structure-aware modeling. 2. The training requires part-segmentation labels as well as closed vocabulary part classes. This limits the generalization ability of the network to larger dataset such as Objaverse. 3. T
- The explicit consideration of symmetry in the 3D point cloud generation process is a novel exploration, and the evaluation, especially the SDI metric in Tables 1 and 3, clearly demonstrates the effectiveness of the proposed framework. - Additionally, the proposed framework achieves state-of-the-art performance compared to existing point cloud generation methods on standard metrics (1-NNA in Table 1), showcasing the quality and diversity of generated shapes. - A thorough ablation study in Table
Despite the strong performance shown, I still have some concerns regarding the evaluation setting. 1. Data Split Concerns. In Table 1, the evaluation protocol follows PointFlow (Yang et al., 2019), which uses the full category dataset for train/test splitting. Since this work uses ShapeNetPart, a subset of that data, it is unclear whether the train/test split remains consistent. If not, the test set may have leaked into the training set. Clarification is needed to ensure fair evaluation. 2. Com
- Clear conceptual decomposition: Factorizing generation into interpretable aspects (shape latent, symmetry, parts, assembly) is an elegant way to inject structure and inductive bias that matches human intuition about object design. - Solid empirical gains: The method shows strong improvements on classical generation metrics (1-NNA / Chamfer) and on the proposed symmetry metric (SDI), indicating both fidelity and structural plausibility. - Symmetry guarantees: Enforcing symmetry in the part gene
- While the authors introduced an evaluation metric for symmetry-awareness, the work does not explicitly evaluate the part-awareness such as in SeaLion (Zhu et al., 2025). - The method is only evaluated on three object classes of ShapeNet. - Related work could be improved and be made more readable. The section seems only like an assembly of many citations without having a flow content-wise. - The figures can be improved as often the point clouds overlap with text boxes, making the figures less
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Taxonomy
Topics3D Shape Modeling and Analysis · Generative Adversarial Networks and Image Synthesis · Robot Manipulation and Learning
