DICArt: Advancing Category-level Articulated Object Pose Estimation in Discrete State-Spaces
Authors: Li Zhang, Mingyu Mei, Ailing Wang, Xianhui Meng, Yan Zhong, Xinyuan Song, Liu Liu, Rujing Wang, Zaixing He, Cewu Lu
Organizations: University of Science and Technology of China · Zhejiang University · East China Normal University · Peking University · Emory University · Hefei University of Technology · Jianghuai Advance Technology Center · Anhui Provincial Key Laboratory of Humanoid Robots · Shanghai Jiao Tong University
Articulated object pose estimation is a core task in embodied AI. Existing methods typically regress poses in a continuous space, but often struggle with 1) navigating a large, complex search space and 2) failing to incorporate intrinsic kinematic constraints. In this work, we introduce DICArt (DIsCrete Diffusion for Articulation Pose Estimation), a novel framework that formulates pose estimation as a conditional discrete diffusion process. Instead of operating in a continuous domain, DICArt progressively denoises a noisy pose representation through a learned reverse diffusion procedure to recover the GT pose. To improve modeling fidelity, we propose a flexible flow decider that dynamically determines whether each token should be denoised or reset, effectively balancing the real and noise distributions during diffusion. Additionally, we incorporate a hierarchical kinematic coupling strategy, estimating the pose of each rigid part hierarchically to respect the object's kinematic structure. We validate DICArt on both synthetic and real-world datasets. Experimental results demonstrate its superior performance and robustness. By integrating discrete generative modeling with structural priors, DICArt offers a new paradigm for reliable category-level 6D pose estimation in complex environments.
Figures & tables
Figure 1: Comparison of Different Denoising Processes. We denote the rotation-related Euler angles as l,m,n , and model them using discretized bin indices for prediction. (a) illustrates the vanilla denoising process of conventional discrete diffusion models, where inconsistent convergence rates across tokens often introduce uncertainty and ambiguity in pose prediction—this can be viewed as an aggressive denoising strategy. (b) presents the reformulated denoising process proposed in this work, which is centered around a customized Flowing Mechanism . This mechanism introduces adaptive directional guidance that determines appropriate update paths for each token. It is designed to enforce consistent convergence trajectories among semantically correlated token groups, thereby enabling a more stable and gentle denoising process. Note that a rigid part ( bottle ) is chosen to illustrate the process for simplicity.
Figure 2: The Pipeline of Our DICArt. Please note that images of the object with varying saturation levels represent different degrees of noise in the pose annotations.
Category
Method
Per-part 6D Pose
Axis Descriptor
Rotation Error ( ∘ ) ↓
Translation Error (m) ↓
Angle Error ( ∘ ) ↓
Distance Error (m) ↓
Laptop
A-NCSH [ 24 ]
5.3, 5.4
0.054, 0.043
1.7
0.09
GenPose [ 48 ]
5.3, 6.1
0.068, 0.060
3.8
0.03
OP-Align [ 6 ]
6.3, 5.2
0.072, 0.058
4.5
0.11
ShapePose [ 58 ]
5.0, 4.6
0.052, 0.064
3.3
0.06
DICArt (Ours)
3.2 , 3.9
0.045 , 0.040
0.8
0.04
Table 1: Comparisons on the ArtImage Dataset. We validate our DICArt on five categories (Laptop, Eyeglasses, Dishwasher, Scissors, and Drawer) that contain 2, 3, 2, 2, 4 parts, respectively.
Figure 3: Qualitative Results on the Synthetic Dataset (left) and RGB-D Images Dataset (right).
Index
Diffusion
Rotation Error ( ∘ )
Translation Error ( m )
I
Continuous
3.1
0.143
II
Discrete
1.7
0.072
Index
Occlusion Level (Visibility)
Rotation Error ( ∘ )
Translation Error ( m )
III
0%-40%
1.8
0.089
IV
40%-80%
1.9
0.096
V
80%-100%
1.9
0.107
Table 2: Ablation Study Results . Experiments are conducted on the category Drawer .
Category
Method
Per-part Pose
Rotation Error ( ∘ )
Translation Error (m)
Box
ReArtNet [ 28 ]
3.3, 3.4
0.026, 0.031
DICArt (Ours)
1.5 , 1.6
0.009 , 0.010
Stapler
ReArtNet [ 28 ]
5.1, 6.5
0.035, 0.031
DICArt (Ours)
2.5 , 3.2
0.008 , 0.012
Cutter
ReArtNet [ 28 ]
3.3, 3.0
0.019, 0.014
Table 3: Pose Estimation Results on ReArtMix Dataset .
Per-part Rotation Error ( ∘ )
Part ID
1
2
3
4
5
6
7
A-NCSH [ 24 ]
7.8
7.9
10.3
10.5
11.2
16.4
23.5
DICArt (Ours)
1.6
4.8
7.8
7.9
8.1
12.3
15.1
Per-part Translation Error (m)
Part ID
1
2
3
4
5
6
7
A-NCSH [ 24 ]
0.012
0.044
0.067
0.066
0.179
0.236
0.403
Table 4: Pose Estimation Results on 7-part RobotArm Dataset.
Figure 4: Qualitative Results on 7-part RobotArm Dataset.
6D pose estimation is a key task in computer vision and embodied AI, widely used in robotic manipulation, augmented reality, etc. Existing methods directly regress in a high-dimensional continuous space, facing two key challenges in category-level pose estimation: limited accuracy due to noise and local optima, and inefficient search over an infinite space that hinders real-time performance. This paper proposes Flow6D, a hierarchical flow matching framework with a two-stage discrete latent space localization-continuous pose regression strategy. Rotation and translation parameters are first discretized into bins, with a discrete flow matching model locking the latent space around the true pose to reduce search complexity. Then, by sampling in the latent space, a continuous flow matching model predicts local pose residuals to optimize the estimate and regress to an accurate pose. The framework also naturally extends to articulated objects, outperforming state-of-the-art methods on synthetic and real datasets with real-time inference at 70 FPS. Project website: https://flow6d.github.io/.
Mingyu Mei, Li Zhang, Zibo Dai +4
Zhejiang University · University of Science and Technology of China · Shanghai Jiao Tong University
Articulated objects are essential for embodied AI and world models, yet inferring their kinematics from a single closed-state image remains challenging because crucial motion cues are often occluded. Existing methods either require multi-state observations or rely on explicit part priors, retrieval, or other auxiliary inputs that partially expose the structure to be inferred. In this work, we present DailyArt, which formulates articulated joint estimation from a single static image as a synthesis-mediated reasoning problem. Instead of directly regressing joints from a heavily occluded observation, DailyArt first synthesizes a maximally articulated opened state under the same camera view to expose articulation cues, and then estimates the full set of joint parameters from the discrepancy between the observed and synthesized states. Using a set-prediction formulation, DailyArt recovers all joints simultaneously without requiring object-specific templates, multi-view inputs, or explicit part annotations at test time. Taking estimated joints as conditions, the framework further supports part-level novel state synthesis as a downstream capability. Extensive experiments show that DailyArt achieves strong performance in articulated joint estimation and supports part-level novel state synthesis conditioned on joints. Project page is available at https://rangooo123.github.io/DaliyArt.github.io/.
Hang Zhang, Qijian Tian, Jingyu Gong +4
East China Normal University · Shanghai AI Lab · Shanghai Jiao Tong University +1
Category-level 6D object pose estimation is typically formulated as a multi-category joint learning problem with fully shared model parameters. However, pronounced geometric heterogeneity across categories entangles incompatible optimization signals in shared modules, resulting in gradient conflicts and negative transfer during training. To address this challenge, we first introduce gradient-based diagnostics to quantify module-level cross-category contention. Building on results of diagnostics, we propose DecomPose, a difficulty-aware decomposition framework that mitigates optimization contention via: (1) difficulty-aware gradient decoupling, which groups categories using a data-driven difficulty proxy and routes each instance to a group-specific correspondence branch to isolate incompatible updates; and (2) stability-driven asymmetric branching, which assigns higher-capacity branches to structurally simple categories as stable optimization anchors while constraining complex categories with lightweight branches to suppress noisy updates and alleviate negative transfer. Extensive experiments on REAL275, CAMERA25, and HouseCat6D demonstrate that DecomPose effectively reduces cross-category optimization contention and delivers superior pose estimation performance across multiple benchmarks.
Yifan Gao, Lu Zou, Zhangjin Huang +1
Hubei Key Laboratory of Intelligent Robot, Wuhan Institute of Technology, Wuhan, Hubei, China · University of Science and Technology of China, Hefei, Anhui, China · Peking University, Beijing, China