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Lidar-based Norwegian tree species detection using deep learning
Proceedings of the 5th Northern Lights Deep Learning Conference ({NLDL}), PMLR 233:228-234, 2024.
Abstract
Background: The mapping of tree species within Norwegian forests is a time-consuming process, involving forest associations relying on manual labeling by experts. The process can involve aerial imagery, personal familiarity, on-scene references, and remote sensing data. The state-of-the-art methods usually use high-resolution aerial imagery with semantic segmentation methods. Methods: We present a deep learning based tree species classification model utilizing only lidar (Light Detection And Ranging) data. The lidar images are segmented into four classes (Norway Spruce, Scots Pine, Birch, background) with a U-Net based network. The model is trained with focal loss over partial weak labels. A major benefit of the approach is that both the lidar imagery and the base map for the labels have free and open access. Results: Our tree species classification model achieves a macro-averaged $\mathrm{F}_1$ score of 0.70 on an independent validation with National Forest Inventory (NFI) in-situ sample plots. That is close to, but below the performance of aerial, or aerial and lidar combined models.