Understanding the dynamic properties of trees using the motions constructed from multi-beam flash light detection and ranging measurements

Abstract

Measuring the three-dimensional motion of trees at every position remains challenging as it requires dynamic measurement technology with sufficient spatial and temporal resolution. Consequently, this study explores the use of a novel multi-beam flash light detection and ranging (LiDAR) sensor to tackle such a sensing barrier. A framework is proposed to record tree vibrations, to construct the motions of tree skeletons from the point-cloud frames recorded by the LiDAR sensor and to derive the dynamic properties of trees. The feasibility of the framework is justified through measurement on a Ficus microcarpa under pull-and-release tests. The relative differences for the first two modal frequencies between the LiDAR and linear variable differential transformer measurements in the displacement Fourier spectra are 0.1% and 2.5%, respectively. The framework is further adopted to study the dynamic response of different trees subjected to typhoons, including a Liquidambar formosana , three Araucaria heterophylla trees, a Sterculia lanceolata , a Celtis sinensis , a Tabebuia chrysantha and a Cinnamomum camphora . Results suggest that broadleaved trees might exhibit vibration in a wide frequency band, whereas the coniferous trees could follow a distinct dominant frequency.

Place Recognition through Multiple LiDAR Scans Based on the Hidden Markov Model

“…Our method can also be extended to LiDAR surveying scenes with non-moving objects, leveraging the HMM framework to detect and distinguish between static and dynamic elements within the scene, as demonstrated in the study by Chau et al [ 35 ]. Further analysis of this application will be conducted in future work.…”

The Performance of Discriminative Tracking Algorithms for the Sway Frequency Measurement of Betula platyphylla Sukaczev (Individual Branch and Tree) under Artificial and Natural Excitation

“…In the selection of research objects, only a leafless birch branch and a leafless deciduous tree were selected, and more research objects (multiple leafless branches and multiple leafless trees), branches with leaves, full-leaf trees and other tree species were not tested. Chau et al used a novel multi-beam flash light detection and ranging (LiDAR) sensor to measure the frequencies of one Liquidambar formosana, three Araucaria heterophylla trees, one Sterculia lanceolata, one Celtis sinensis, one Tabebuia chrysantha and one Cinnamomum camphora, and found that broadleaved trees might exhibit vibration in a wide frequency band, whereas the coniferous trees could follow a distinct dominant frequency [20]. In addition, in the discussion of tracking situation, only qualitative analysis was carried out, without quantitative comparison.…”

“…Additionally, the mass of the devices themselves may affect the measurement results and cause damage to the trees. Non-contact-based measurement methods include a laser Doppler interferometer [16], prism system [17], magnetic sensor [18], Kinect [19], a novel multi-beam flash light detection and ranging (LiDAR) sensor [20] and video [1,11,18] methods. However, most non-contact measurement methods suffer from limitations in practicality, limited measurement distance, and low cost-effectiveness [1].…”

A novel approach for analyzing the dynamic properties of trees with fractal sympodial branching architecture: a group tree modeling

“…They suggested that the monopodial trees could have weaker wind-induced vibration than the sympodial trees. Chau et al [10] measured and analyzed the trees' dynamic properties under free-decay motions and typhoon-induced vibrations. Results revealed that coniferous trees might vibrate with distinct frequencies, while the broadleaved trees would exhibit a broadband vibration.…”