The development of terrestrial laser scanning (TLS) has opened new avenues in the study of trees. Although TLS provides valuable information on structural elements, fine-scale analysis, e.g., at the ...annual shoots (AS) scale, is currently not possible. We present a new model to segment and classify AS from tree skeletons into a finite set of “physiological ages” (i.e., state of specialization and physiological age (PA)). When testing the model against perfect data, 90% of AS year and 99% of AS physiological ages were correctly extracted. AS length-estimated errors varied between 0.39 cm and 2.57 cm depending on the PA. When applying the model to tree reconstructions using real-life simulated TLS data, 50% of the AS and 77% of the total tree length are reconstructed. Using an architectural automaton to deal with non-reconstructed short axes, errors associated with AS number and length were reduced to 5% and 12%, respectively. Finally, the model was applied to real trees and was consistent with previous findings obtained from manual measurements in a similar context. This new method could be used for determining tree phenotype or for analyzing tree architecture.
The high-resolution quantification of the sediment transit in mountain streams by the use of terrestrial laser scan is particularly promising for the dynamic knowledge (volumes, time-storage) and for ...the protection works management (filling follow-up, clearing planning). However, the singular situation of those environments and the difficult survey conditions produce complex stages of treatment and dictate additional operations. This text presents an experience feedback on the sediment transport by comparaison of high-resolution digital terrain models of four torrential sections in the Northern Alps. It aims to refine the terrestrial laser data acquisition protocol and then improve treatments.
La quantification à haute résolution du transit sédimentaire dans les systèmes torrentiels par l'utilisation du LiDAR terrestre est particulièrement prometteuse pour la connaissance de la dynamique (quantification des volumes, durée de stockage) et pour la gestion des ouvrages de protection (suivi du remplissage, programmation des curages). Toutefois, la situation particulière de ces milieux et les conditions de levés difficiles qui en découlent rendent les étapes de traitement complexes et imposent des opérations complémentaires. Ce texte présente un premier retour d'expérience sur le suivi numérique de nappes caillouteuses par la comparaison de MNT à haute résolution de quatre tronçons torrentiels dans les Alpes du nord. Il vise à mettre en exergue les difficultés rencontrées, les choix réalisés et les enseignements tirés pour affiner le protocole d'acquisition de données laser terrestre et améliorer les traitements.
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