High-Precision Multi-Instance Registration for Stacked Objects in Bin-Picking Scenes

In industrial bin-picking, robotic systems must estimate the poses of multiple object instances, where accurate pose estimation is essential for reliable downstream manipulation and grasping. Most existing multi-instance registration methods primarily establish point correspondences based on local features to alleviate the challenges posed by occlusion and clutter. However, local features are easily disturbed by neighboring instances and lack global context, leading to unreliable correspondences and degraded registration accuracy. In addition, the absence of rotational invariance further reduces correspondence accuracy in scenes with stacked instances and highly varying object orientations. To address these challenges, we present a one-stage multi-instance point cloud registration framework for stacked-object scenes. Our framework incorporates a rotation-invariant operator to enhance the robustness of feature representations under arbitrary orientations. Then, we propose a Center-Aware Res-Masked Transformer module, which incorporates an object center embedding to enrich global instance-level context and a center-aware residual mask prediction module to balance weight distribution across objects of varying sizes during training. Extensive experiments on the challenging ROBI dataset demonstrate that our method outperforms the competitive baseline MIRETR by more than 10% in mean precision, highlighting its effectiveness in complex bin-picking scenes. Furthermore, evaluations on the unstacked Scan2CAD dataset confirm the generalizability of the proposed framework across different application scenarios.