Boosting Novel Category Discovery Over Domains with Soft Contrastive Learning and All in One Classifier

Unsupervised domain adaptation (UDA) has proven to be highly effective in transferring knowledge from a label-rich source domain to a label-scarce target domain. However, the presence of additional novel categories in the target domain has led to the development of open-set domain adaptation (ODA) and universal domain adaptation (UNDA). Existing ODA and UNDA methods treat all novel categories as a single, unified unknown class and attempt to detect it during training. However, we found that domain variance can lead to more significant view-noise in unsupervised data augmentation, which affects the effectiveness of contrastive learning (CL) and causes the model to be overconfident in novel category discovery. To address these issues, a framework nameded Soft-contrastive All-in-one Network (SAN) is proposed for ODA and UNDA tasks. SAN includes a novel data-augmentation-based soft contrastive learning (SCL) loss to fine-tune the backbone for feature transfer and a more human-intuitive classifier to improve new class discovery capability. The SCL loss weakens the adverse effects of the data augmentation view-noise problem which is amplified in domain transfer tasks. The All-in-One (AIO) classifier overcomes the overconfidence problem of current mainstream closed-set and open-set classifiers. Visualization and ablation experiments demonstrate the effectiveness of the proposed innovations. Furthermore, extensive experiment results on ODA and UNDA show that SAN outperforms existing state-of-the-art methods.

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Task Dataset Model Metric Name Metric Value Global Rank Benchmark
Universal Domain Adaptation DomainNet SAN H-Score 52.0 # 4
Source-free no # 1
Universal Domain Adaptation Office-31 SAN H-score 91.8 # 3
Source-Free no # 1
Universal Domain Adaptation Office-Home SAN H-Score 75.9 # 4
Source-free no # 1
Universal Domain Adaptation VisDA2017 SAN H-score 60.1 # 5
Source-free no # 1

Methods