Multi-View Vision-to-Geometry Knowledge Transfer for 3D Point Cloud Shape Analysis

As two fundamental representation modalities of 3D objects, 2D multi-view images and 3D point clouds reflect shape information from different aspects of visual appearances and geometric structures. Unlike deep learning-based 2D multi-view image modeling, which demonstrates leading performances in various 3D shape analysis tasks, 3D point cloud-based geometric modeling still suffers from insufficient learning capacity. In this paper, we innovatively construct a unified cross-modal knowledge transfer framework, which distills discriminative visual descriptors of 2D images into geometric descriptors of 3D point clouds. Technically, under a classic teacher-student learning paradigm, we propose multi-view vision-to-geometry distillation, consisting of a deep 2D image encoder as teacher and a deep 3D point cloud encoder as student. To achieve heterogeneous feature alignment, we further propose visibility-aware feature projection, through which per-point embeddings can be aggregated into multi-view geometric descriptors. Extensive experiments on 3D shape classification, part segmentation, and unsupervised learning validate the superiority of our method. We will make the code and data publicly available.