RS-MTDF: Multiteacher Distillation and Fusion for Remote Sensing Semi-Supervised Semantic Segmentation

Semantic segmentation in remote sensing (RS) images is crucial for various applications, yet its performance is heavily reliant on large-scale, high-quality pixel-wise annotations, which are notoriously expensive and time-consuming to acquire. Semi-supervised semantic segmentation (SSS) offers a promising alternative to mitigate this data dependency. However, existing SSS methods often struggle with the inherent distribution mismatch between limited labeled data and abundant unlabeled data, leading to suboptimal generalization. To alleviate this issue, we attempt to introduce vision foundation models (VFMs) pretrained on vast and diverse datasets into the SSS task since VFMs possess robust generalization capabilities that can effectively bridge this distribution gap and provide strong semantic priors for SSS. Inspired by this, we introduce RS-MTDF (multiteacher distillation and fusion), a novel framework that leverages the powerful semantic knowledge embedded in VFMs to guide semi-supervised learning in RS. Specifically, RS-MTDF employs multiple frozen VFMs (e.g., DINOv2 and CLIP) as expert teachers, utilizing feature-level distillation to align student features with their robust representations. To further enhance discriminative power, the distilled knowledge is seamlessly fused into the student decoder. Extensive experiments on three challenging RS datasets (ISPRS Potsdam, LoveDA, and DeepGlobe) demonstrate that RS-MTDF achieves state-of-the-art or comparable performance. Notably, our method outperforms existing approaches across various label ratios on LoveDA and secures the highest IoU in the majority of semantic categories. These results underscore the efficacy of multiteacher VFM guidance in significantly enhancing both generalization and semantic understanding for RS segmentation. Ablation studies further validate the contribution of each proposed module. Code is available at https://github.com/earth-insights/RS-MTDF