Copy-Rotate-Paste Augmentation for Point Cloud Segmentation

Point cloud segmentation (PCS) aims to classify each point in a point cloud. The task plays an important role in robotics and remote sensing. However, existing copy-paste and copy-rotate-paste augmentation techniques cause undesirable artifacts in the augmented point cloud and cannot effectively copy and paste interesting objects from the whole training dataset, bringing difficulty in training image-points fused models and leading to sub-optimal PCS performance. In this paper, we propose an improved virtual range image-guided copy-rotate-paste (VRCrop++) strategy and a global copy-rotate-paste (GCrop) technique. VRCrop++ and GCrop remove unwanted artifacts in the augmented point cloud by a simple but effective “point-to-patch” strategy in the pasting step. Besides, GCrop copies the objects globally with the reciprocal of the point distribution ratio and effectively pastes the objects considering the minimal overlapping region. Extensive experiments conducted on SemanticKITTI and SemanticPOSS datasets demonstrate that with VRCrop++ and GCrop, the existing range image-points fused models consistently surpass their counterparts.