Revisiting the Domain Shift and Sample Uncertainty in Multi-source Active Domain Transfer
Authors: Wenqiao Zhang, Zheqi Lv, Hao Zhou, Jia-Wei Liu, Juncheng Li, Mengze Li, Yunfei Li, Dongping Zhang, Yueting Zhuang, Siliang Tang

Active Domain Adaptation (ADA) aims to maximally boost model adaptation in a new target domain by actively selecting a limited number of target data to annotate. This setting neglects the more practical scenario where training data are collected from multiple sources. This motivates us to extend ADA from a single source domain to multiple source domains termed Multi-source Active Domain Adaptation (MADA). Not surprisingly we find that most traditional ADA methods cannot work directly in such a setting mainly due to the excessive domain gap introduced by all the source domains. Considering this we propose a Detective framework that comprehensively considers the domain shift between multi-source domains and target domains to detect the informative target samples. Specifically the Detective leverages a dynamic Domain Adaptation (DA) model that learns how to adapt the model's parameters to fit the union of multi-source domains. This enables an approximate single-source domain modeling by the dynamic model. We then comprehensively measure both domain uncertainty and predictive uncertainty in the target domain to detect informative target samples using evidential deep learning thereby mitigating uncertainty miscalibration. Experiments demonstrate that our solution outperforms existing methods by a considerable margin on three domain adaptation benchmarks.