Interpretable Novel Target Discovery through Open-Set Domain Adaptation

Open-set domain adaptation (OSDA) considers a special domain adaptation problem in which the target domain contains novel categories that never appear in the well-labeled source domain. Unfortunately, prior efforts on OSDA simply detect and recognize all novel categories as one “unknown” group without further exploration. The demand for exploring these novel categories prompts us to consider the underlying multi-class structure and semantic description of those unknown categories in more detail. In this article, we propose a novel interpretable framework to accurately identify the seen categories in the target domain and effectively recover the semantic knowledge of the unseen categories with attributes and visual interpretations, which is referred to as Semantic Recovery Open-Set Domain Adaptation (SR-OSDA). Specifically, the proposed framework includes an explicit attribute explainable module and an implicit semantic interpretable module, which provide insight into the process of domain adaptation and the discovery of new categories. Furthermore, structure-preserving partial alignment is developed as a method of recognizing and aligning the visible categories across domains with the aid of domain-invariant feature learning. The visual-structural semantic attributes propagation is designed to provide smooth transitions from seen categories to unseen categories via visual-semantic mapping. Three new cross-domain SR-OSDA benchmarks are constructed in order to evaluate the proposed framework in novel and practical challenges. Experimental results and empirical analysis of our proposed solution to open-set recognition and semantic recovery demonstrate its superiority over other state-of-the-art solutions. Our source code is available at https://github.com/scottjingtt/XSROSDA .