HGACNet: Hierarchical Graph Attention Network for Cross-Modal Point Cloud Completion

Abstract

Point cloud completion is essential for robotic perception, object reconstruction and supporting downstream tasks like grasp planning, obstacle avoidance, and manipulation. However, incomplete geometry caused by self-occlusion and sensor limitations can significantly degrade downstream reasoning and interaction. To address these challenges, we propose HGACNet, a novel framework that reconstructs complete point clouds of individual objects by hierarchically encoding 3D geometric features and fusing them with image-guided priors from a single-view RGB image. At the core of our approach, the Hierarchical Graph Attention (HGA) encoder adaptively selects critical local points through graph attention-based downsampling and progressively refines hierarchical geometric features to better capture structural continuity and spatial relationships. To strengthen cross-modal interaction, we further design a Multi-Scale Cross-Modal Fusion (MSCF) module that performs attention-based feature alignment between hierarchical geometric features and structured visual representations, enabling fine-grained semantic guidance for completion. In addition, we proposed the contrastive loss (C-Loss) to explicitly align the feature distributions across modalities, improving completion fidelity under modality discrepancy. Finally, extensive experiments conducted on both the ShapeNet-ViPC benchmark and the YCB-Complete dataset confirm the effectiveness of HGACNet, demonstrating state-of-the-art performance as well as strong applicability in real-world robotic manipulation tasks.