Current object pose estimation research remains predominantly model-centric, focusing on architectural innovations and post-processing refinements. This paper introduces a data-centric optimization by proposing a novel, physically grounded rotation representation through principal axes alignment. Our method aligns the object's coordinate system with its inherent geometric axes, derived from inertial properties, yielding three key advantages: Inherent Stability-leveraging the energy-minimizing property of principal axes provides a robust representation that is less sensitive to noise and occlusions; Symmetry-Aware Canonicalization-explicitly resolving rotational ambiguities for symmetric objects at the data level, which fundamentally eliminates label confusion during network training; and Framework Agnosticism-the optimization is applied purely at the dataset level, ensuring plug-and-play compatibility with existing networks without any architectural modification. We validate the framework across diverse category-level and instance-level models. Extensive experiments demonstrate consistent and significant accuracy improvements, while preserving the integrity of the baseline network. This work establishes a new, geometry-driven direction for enhancing pose estimation, circumventing the need for complex network redesign.
Figures & tables
Fig. 1: Semantic illustration of proposed mechanism .The main contribution of previous methods mainly focused on network layout update, including new loss functions or new network architectures. Our proposed method only updates the rotation coordinate for pose representation, which is easy to apply and perfectly compatible with existing methods.
Fig. 2: Overview of the proposed mechanism and its usage. There are four main steps of our proposed mechanism. First, we calculate the principal axes of the object’s inertia, and then we form the transformation rotation using these three principal axes. Third, we access the new object coordinate for the datasets with the transformation rotation. Then, we eliminate the rotation ambiguity with the proposed module if the objects are symmetric. Finally, we retrain the network using datasets in new coordinates, eliminating rotation ambiguity.
Fig. 3: Physics property of π -Mechanism . For original coordinates, the non-diagonal elements are non-zero. For the object in Principal Axes, the non-diagonal elements are close to zero.
Fig. 4: Illustration of the effect of π -Mechanism . The above row shows the geometric relation between the object and its coordinates. When the rotation value is 0, the orientation of the object is not aligned well with the axes of the object coordinate. The second row of images shows the relation when applying our proposed mechanism to the original object relation. The orientation of the object is aligned well with its coordinate.
Fig. 5: A Taxonomy of 3D Objects Based on Rotational Symmetry Around Two Principal Axes . We systematically categorize objects’ shapes by their rotational symmetry properties around two independent principal inertial axes. The rows and columns represent the four fundamental symmetry types for a single axis: Continuous, N-fold Discrete, 2-fold, and Asymmetric. Each cell provides one or two canonical 3D object examples (without considering the color texture) exhibiting the corresponding pairwise combination of symmetries.
Fig. 6: Pipeline for resolving rotational ambiguity in symmetric objects. Left top: Computation of the principal axes of inertia from the object’s geometry. Right top: Symmetry type classification (e.g., two-fold symmetry) based on the principal axes. Right bottom: Generation of canonical candidate vectors. Left bottom: Final unambiguous rotation representation obtained after disambiguation.
Fig. 7: Illustration of rotation disambiguation for symmetric objects. Left column: Distribution of rotation viewpoints in the original ambiguous space. Middle column: 3D model of the object in the TLESS dataset (obj29, obj27, obj14), highlighting its intrinsic symmetry. Right column: Unique distribution of rotation viewpoints after ambiguity resolution.
Fig. 8: Illustration of Geometric Vectors for Different Symmetry Types.
Method
Ape
Bench Vise
Camera
Can
Cat
Driller
Glue
Hole Puncher
Iron
Lamp
Phone
Average
PointNet [ 43 ]
12.28
12.49
11.76
13.71
13.11
11.30
10.72
10.23
11.62
10.47
11.09
11.71
PointNet + π -Mechanism
12.12
10.30
10.27
13.16
12.51
11.26
11.41
12.34
11.42
10.01
9.71
11.32
Si-Mamba [ 44 ]
10.85
11.04
10.42
11.34
11.22
11.06
10.13
12.55
10.17
11.57
11.34
11.06
Si-Mamba + π -Mechanism
10.48
10.58
10.05
11.94
10.26
10.49
9.86
11.46
10.67
10.25
10.72
10.61
TABLE I: Rotation error for different methods on the synthetic LINEMOD dataset. The best result is bolded.
Method
Ape
Bench Vise
Camera
Can
Cat
Driller
Duck
Hole Puncher
Iron
Lamp
Phone
Average
G2L [ 50 ]
7.37
15.34
5.99
8.96
6.03
13.04
6.84
5.13
17.20
12.54
7.24
9.61
G2L + π -Mechanism
6.25
11.94
5.83
6.30
5.23
9.37
6.58
3.94
7.37
9.79
5.44
7.09
GDR-Net [ 27 ]
2.11
1.85
1.81
1.82
2.02
2.02
1.98
1.96
2.33
1.87
2.30
2.01
GDR-Net+ π -Mechanism
1.83
1.82
1.67
1.73
1.80
1.83
1.83
1.88
2.04
1.68
2.19
1.83
TABLE II: Rotation error for different methods on LINMOD dataset. The best result is bolded.
Fig. 9: Mean rotation errors with standard deviation (SD). The left bar is the mean rotation error and SD of the baseline method; The right bar is the mean rotation error and SD of the proposed mechanism.
Fig. 10: The Quantitative results for the LINEMOD dataset. The green boxes are the ground truth. The red boxes are our results. The blue boxes are the results of the baseline.
Methods
Ape
Can
Cat
Driller
Duck
Egg box
Glue
Hole Puncher
Average
LC
44.44%
89.06%
49.87%
87.81%
56.08%
62.81%
68.88%
72.89%
66.69%
LC+ π -M
48.97%
90.22%
51.39%
89.46%
57.31%
65.37%
70.86%
76.61%
68.99%
TABLE III: Results on dataset LINEMOD-OCCLUDE for method GDR-LC [ 14 ] in ADD(-S)-0.1d metric (the higher is better). The best result is bolded. For symmetric objects ‘Egg Box’ and ‘Glue’, the ADD-S scores are reported.
Fig. 11: The Quantitative results for LINEMOD-OCC dataset. The green boxes are the ground truth. The red boxes are our results. The blue boxes are the results of the baseline.
Method
obj 14
obj 27
obj 29
G2L [ 50 ]
31.51
71.70
108.83
G2L + π -Mechanism
2.64
10.11
17.79
TABLE IV: Rotation error for different methods on TLESS symmetric objects. The best result is bolded.
Fig. 12: ‘Camera’ category with different instances
Category
Bottle
Bowl
Can
Camera
Laptop
Mug
Average
different representation
FS-Net
5.71
3.85
3.97
21.59
8.00
13.77
9.48
FS-Net+ π -Mechanism
5.34
3.64
3.58
20.99
7.57
12.40
8.92
TABLE V: Rotation error comparison. Results on dataset NOCS-REAL for method FS-Net [ 6 ] in rotation prediction error. The best result is bolded.
Fig. 13: Loss value comparison . Left: the loss value comparison between original datasets and datasets in Principal Axes coordinates. Right: the loss ratio between original and principal over training iterations.
Object pose estimation is a fundamental problem in 3D vision. Although recent state-of-the-art approaches achieve strong performance, generalization to novel categories and unseen scenes remains challenging. We propose UniPose9D, a unified model for category-agnostic 9D object pose estimation: given an instance mask/ROI and either an RGB-D observation or an RGB image with predicted depth, the model estimates rotation, translation, and metric size without category labels, CAD models, mean-shape priors, or reference views. Specifically, UniPose9D samples point pairs from the observed object geometry and uses DINOv2 and PointNet features to predict NOCS coordinates for each pair. To improve accuracy, we introduce a point-pair-based RANSAC N-hop Kabsch-Umeyama algorithm with an adaptive threshold. We further employ flow matching to address symmetric ambiguities and construct a large-scale training set by curating and aligning pose annotations from existing public datasets. Experiments across eight datasets show that a single unified model achieves competitive performance on standard benchmarks while generalizing to unseen objects, unseen categories, and in-the-wild scenarios. Our code and model are available at https://github.com/qq456cvb/UniPose9D.
Category-level object pose estimation seeks to recover a similarity transform (R,t,s) for unseen instances without instance-specific CAD models. Most competitive methods are correspondence-based: prior-free variants regress canonical (NOCS) coordinates directly from local observations and implicitly memorize the canonical frame in the weights, which ties the parameters to category-typical orientations and hurts generalization under distribution shift; prior-based variants introduce a category prior but typically follow a serial deform-then-align pipeline, where underconstrained canonical completion can corrupt correspondences and induce error cascades in pose. We propose PriorPose, a reference-guided correspondence framework that keeps the category prior explicit and solves canonicalization and alignment jointly in a shared feature space. A reference-guided seeded transformer embeds the partial observation and the category prior as token sets and fuses them via geometry-aware seeds, from which the network jointly predicts a per-point NOCS field for visible points and a canonical deformation of the prior that reconstructs a full canonical instance, while a deep pose head regresses (R,t,s) from the induced correspondences. A two-part shape consistency objective, with canonical-space and camera-space consistency losses, couples correspondence, deformation, and pose, reducing reliance on memorized canonical orientations and avoiding deform-then-align error cascades. Experiments on standard and larger-category benchmarks demonstrate that PriorPose sets new state-of-the-art results on most evaluated metrics, especially under strict pose thresholds, while remaining competitive on relaxed pose and IoU metrics and showing improved robustness under shape variation and domain shift.
Yihan Chen, Huan Ren, Wenfei Yang +3
School of Information Science and Technology / National Key Laboratory of Deep Space Exploration, University of Science and Technology of China · Beijing Institute of Control Engineering
Object pose estimation is a fundamental problem for an agent system to perceive or manipulate objects in images or videos. However, current instance-level methods struggle with generalization to unseen objects. Category-level methods seek to address this, but remain constrained by the complexities of learning in the non-linear Sim(3) space and intra-class variations. To address these challenges, We propose an effective method for category-level object pose estimation with two key innovations: (1) A translation/size estimator, featuring a semantic-guided symmetry-aware module that leverages robust generalization capabilities of a large vision model (LVM) to infer symmetry points, resulting in accurate translation and size without shape priors. This result serves as a precomputed cue for rotation estimation, thereby reducing the difficulty of learning in the non-linear Sim(3) space and laying a robust foundation for tackling the inherently more challenging rotation estimation. (2) A feature fusion module, based on our proposed spherical large-kernel inception convolution, fuses semantic features from the LVM with systematically computed geometric features to extract essential pose features from intra-class variations by modeling long-range dependencies without excessive computational cost. Built on these innovations, we achieve SOTA on benchmarks and real-world scenes, while developing a robust robotic picking system capable of handling diverse objects. Our code will be available at the project page: {\hypersetup{urlcolor=blue}https://panfei-cheng.github.io/SSH-Pose}.
Panfei Cheng, Hongshan Yu, Wenrui Chen +3
National Engineering Research Center for Robot Visual Perception and Control, School of Robotics and Artificial Intelligence, Hunan University, Changsha 410012, China