Joint Global and Dynamic Pseudo Labeling for Semi-Supervised Point Cloud Sequence Segmentation

Supervised learning is a mainstay for large discriminative models in 3D computer vision, while large amounts of human-annotated data are the key to achieve state-of-the-art performance. This limitation is particularly notable for large-scale point cloud sequence segmentation tasks, because point-level annotations are very time-consuming and especially expensive. To overcome this challenge, we develop a novel semi-supervised framework for point cloud sequences segmentation. Specifically, we develop two kinds of pseudo labeling methods with extracting global semantic information from labeled frames and dynamic information from each sequence respectively. Then the two kinds of generated labels are combined as more robust pseudo labels (GD-Pseudo labels) for unlabeled frames. We finally apply an efficient iterative learning scheme to train a model with a small quantity of human-annotated data and large-scale pseudo-labeled data. Equipped with our framework, the model achieves significant performance improvement (+12-25 mIoU) on SemanticKITTI and Synthia when compared with frameworks that do not utilize large amounts of unlabeled data. Moreover, our method achieves comparable performance with only 20% annotated frames on SemanticKITTI to state-of-the-art models trained with 100% human-annotated frames.