Self-supervised Exclusive Learning for 3D Segmentation with Cross-modal Unsupervised Domain Adaptation

2D-3D unsupervised domain adaptation (UDA) tackles the lack of annotations in a new domain by capitalizing the relationship between 2D and 3D data. Existing methods achieve considerable improvements by performing cross-modality alignment in a modality-agnostic way, failing to exploit modality-specific characteristic for modeling complementarity. In this paper, we present self-supervised exclusive learning for cross-modal semantic segmentation under the UDA scenario, which avoids the prohibitive annotation. Specifically, two self-supervised tasks are designed, named "plane-to-spatial" and "discrete-to-textured". The former helps the 2D network branch improve the perception of spatial metrics, and the latter supplements structured texture information for the 3D network branch. In this way, modality-specific exclusive information can be effectively learned, and the complementarity of multi-modality is strengthened, resulting in a robust network to different domains. With the help of the self-supervised tasks supervision, we introduce a mixed domain to enhance the perception of the target domain by mixing the patches of the source and target domain samples. Besides, we propose a domain-category adversarial learning with category-wise discriminators by constructing the category prototypes for learning domain-invariant features. We evaluate our method on various multi-modality domain adaptation settings, where our results significantly outperform both uni-modality and multi-modality state-of-the-art competitors.