Energy-Based Domain Adaptation Without Intermediate Domain Dataset for Foggy Scene Segmentation

Robust segmentation performance under dense fog is crucial for autonomous driving, but collecting labeled real foggy scene datasets is burdensome in the real world. To this end, existing methods have adapted models trained on labeled clear weather images to the unlabeled real foggy domain. However, these approaches require intermediate domain datasets (e.g. synthetic fog) and involve multi-stage training, making them cumbersome and less practical for real-world applications. In addition, the issue of overconfident pseudo-labels by a confidence score remains less explored in self-training for foggy scene adaptation. To resolve these issues, we propose a new framework, named DAEN, which Directly Adapts without additional datasets or multi-stage training and leverages an ENergy score in self-training. Notably, we integrate a High-order Style Matching (HSM) module into the network to match high-order statistics between clear weather features and real foggy features. HSM enables the network to implicitly learn complex fog distributions without relying on intermediate domain datasets or multi-stage training. Furthermore, we introduce Energy Score-based Pseudo-Labeling (ESPL) to mitigate the overconfidence issue of the confidence score in self-training. ESPL generates more reliable pseudo-labels through a pixel-wise energy score, thereby alleviating bias and preventing the model from assigning pseudo-labels exclusively to head classes. Extensive experiments demonstrate that DAEN achieves state-of-the-art performance on three real foggy scene datasets and exhibits a generalization ability to other adverse weather conditions. Code is available at https://github.com/jdg900/daen.