High-resolution mapping of forest structure from integrated SAR and optical images using an enhanced U-net method

Abstract

Forest structure is an essential part of biodiversity and ecological analysis and provides crucial insights to address challenges in these areas. Modern sensor technologies unlock new possibilities for more advanced vegetation monitoring. This study examines the potential of single high resolution X-band synthetic aperture radar (SAR) and optical images for pixel-wise mapping of four forest structure attributes (height, average height, fractional cover, and density) at a striking 0.5 m resolution. The study site is situated in Western Norway, hosting trees from flatlands to elevated mountainous areas and in-between. The proposed model architecture, called PSE-UNet, is a modified UNet incorporating key components from state-of-the-art deep learning from the field of forest structure monitoring. A comparative analysis involving state-of-the-art models shows promising results with MAE% between 21.5 and 24.7, depending on the variable.