Self-supervised learning approaches for unsupervised domain adaptation (UDA) of semantic segmentation models suffer from challenges of predicting and selecting reasonable good quality pseudo labels. In this paper, we propose a novel approach of exploiting scale-invariance property of the semantic segmentation model for self-supervised domain adaptation. Our algorithm is based on a reasonable assumption that, in general, regardless of the size of the object and stuff (given context) the semantic labeling should be unchanged. We show that this constraint is violated over the images of the target domain, and hence could be used to transfer labels in-between differently scaled patches. Specifically, we show that semantic segmentation model produces output with high entropy when presented with scaled-up patches of target domain, in comparison to when presented original size images. These scale-invariant examples are extracted from the most confident images of the target domain. Dynamic class specific entropy thresholding mechanism is presented to filter out unreliable pseudo-labels. Furthermore, we also incorporate the focal loss to tackle the problem of class imbalance in self-supervised learning. Extensive experiments have been performed, and results indicate that exploiting the scale-invariant labeling, we outperform existing self-supervised based state-of-the-art domain adaptation methods. Specifically, we achieve 1.3% and 3.8% of lead for GTA5 to Cityscapes and SYNTHIA to Cityscapes with VGG16-FCN8 baseline network.

本文提出一种新颖的基于自我监督领域自适应的方法，通过利用语义分割模型的尺度不变性属性，可以在不同尺度的补丁之间转移标签，使用动态类特定熵阈值机制过滤出不可靠的伪标签，并且通过使用焦点损失来解决自我监督学习中的类别不平衡问题，实验结果表明，该方法在GTA5到Cityscapes和SYNTHIA到Cityscapes的数据集上优于基于现有自我监督方法的最新领域自适应方法， VGG16-FCN8基线网络效果提高了1.3％和3.8％。

基于尺度不变示例的语义分割领域自适应学习