“…Typically, UDA methods transfer the knowledge in four ways: 1) directly minimizing the statistical distribution distance between two domains [22], [23]; 2) inducing the domain-invariant feature generation [9], [10], [24]; 3) learning from the synthesized images [25]- [29], and 4) selftraining via pseudo labels [30], [31]. By alleviating the crossdomain discrepancy at the feature and appearance levels, UDA methods have achieved outstanding performance in crossdomain classification [9], [10], [27], segmentation [32]- [34], and detection [11], [13], [14], [30], [35], [36]. Since our proposed method aims at tackling the feature entanglement issue for cross-domain object detection, only the literature of UDA object detection and feature disentanglement are reviewed in detail.…”