“…Here comes to help Unsupervised Domain Adaptation (UDA), which pursues solving a supervised learning task in a Target domain, T , where data come without labels, by leveraging on labeled data available in a Source domain, S. In the last couple of years, an increasing number of papers [4,43,1,2,73] have addressed UDA for point cloud classification, with popular synthetic datasets of CAD models, such as ModelNet40 [65] or ShapeNet [7], and real datasets such as ScanNet [11]. The main line of research focuses on learning an effective feature space for the target domain by means of auxiliary tasks such as point cloud reconstruction [1,46], 3D puzzle sorting [2] and rotation prediction [73]. These tasks are refereed as auxiliary since they do not directly solve the main task, but at the same time, they are useful to learn features for the target domain without the need of annotations.…”