Domain adaptive semantic segmentation aims to transfer knowledge from a labeled source domain to an unlabeled target domain. However, existing methods primarily focus on directly learning qualified target features, making it challenging to guarantee their discrimination in the absence of target labels. This work provides a new perspective. We observe that the features learned with source data manage to keep categorically discriminative during training, thereby enabling us to implicitly learn adequate target representations by simply \textbf{pulling target features close to source features for each category}. To this end, we propose T2S-DA, which we interpret as a form of pulling Target to Source for Domain Adaptation, encouraging the model in learning similar cross-domain features. Also, considering the pixel categories are heavily imbalanced for segmentation datasets, we come up with a dynamic re-weighting strategy to help the model concentrate on those underperforming classes. Extensive experiments confirm that T2S-DA learns a more discriminative and generalizable representation, significantly surpassing the state-of-the-art. We further show that our method is quite qualified for the domain generalization task, verifying its domain-invariant property.

本研究提出了一种新的域自适应语义分割方法T2S-DA，通过将目标特征拉近到源特征中来提高模型的跨域特征表示性能；同时，该方法还采用动态加权策略，使模型可以更好地集中在那些表现较差的像素类别上。实验结果证明，T2S-DA方法学习的表示性能更加明显和具有一般性，且比现有的方法表现更优秀，同时还验证了其领域不变性属性。

将目标拔向源头：关于域自适应语义分割的新视角