High-Resolution Mapping Coastal Wetland Vegetation Using Frequency-Augmented Deep Learning Method

Highlights: First use of very-high resolution (2 cm) image data for Mapping Coastal Wetland Vegetation: We have used drone imagery and deep learning techniques to complete the task of fine tuned classification of Wetland Vegetation. A method for coastal vegetation classification from high resolution imagery is proposed: In this paper, we proposal a augment frequency-domain features network—AFDFNet. Experimental results demonstrate that AFDFNet consistently outperforms existing deep learning models, achieving state-of-the-art performance. An Multi-scale Feature Enhancement Module: We designed a multi-scale feature enhancement module to compensate for the misclassification phenomenon caused by the lack of frequency domain features and contextual information in the network. Coastal wetland vegetation exhibits pronounced spectral mixing, complex mosaic spatial patterns, and small target sizes, posing considerable challenges for fine-grained classification in high-resolution UAV imagery. At present, remote sensing classification of ground objects based on deep learning mainly relies on spectral and structural features, while the frequency domain features of ground objects are not fully considered. To address these issues, this study proposes a vegetation classification model that integrates spatial-domain and frequency-domain features. The model enhances global contextual modeling through a large-kernel convolution branch, while a frequency-domain interaction branch separates and fuses low-frequency structural information with high-frequency details. In addition, a shallow auxiliary supervision module is introduced to improve local detail learning and stabilize training. With a compact parameter scale suitable for real-world deployment, the proposed framework effectively adapts to high-resolution remote sensing scenarios. Experiments on typical coastal wetland vegetation including Reeds, Spartina alterniflora, and Suaeda salsa demonstrate that the proposed method consistently outperforms representative segmentation models such as UNet, DeepLabV3, TransUNet, SegFormer, D-LinkNet, and MCCA across multiple metrics including Accuracy, Recall, F1 Score, and mIoU. Overall, the results show that the proposed model effectively addresses the challenges of subtle spectral differences, pervasive species mixture, and intricate structural details, offering a robust and efficient solution for UAV-based wetland vegetation mapping and ecological monitoring.