The Tracking and Frequency Measurement of the Sway of Leafless Deciduous Trees by Adaptive Tracking Window Based on MOSSE

Abstract

The tree sway frequency is an important part of the dynamic properties of trees. In order to obtain trees sway frequency in wind, a method of tracking and measuring the sway frequency of leafless deciduous trees by adaptive tracking window based on MOSSE was proposed. Firstly, an adaptive tracking window is constructed for the observed target. Secondly, the tracking method based on Minimum Output Sum Of Squared Error Filter (MOSSE) is used to track tree sway. Thirdly, Fast Fourier transform was used to analyze the horizontal sway velocity of the target area on the trees, and the sway frequency was determined. Finally, comparing the power spectral densities (PSDs) of the x axis acceleration measured by the accelerometer and PSDs of the x axis velocity measured by the video, the fundamental sway frequency measured by the accelerometer is equal to the fundamental sway frequency measured by video. The results show that the video-based method can be used successfully for measuring the sway frequency of leafless deciduous trees.

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

“…Wind has a significant impact on individual trees or entire forest stands, and it is one of the main causes of forest disasters. In strong winds, trees may break or be uprooted due to excessive wind load [1,2], resulting in a decrease in timber production and causing economic losses [3][4][5]. Tree sway frequency is an important part of the dynamic characteristics of trees.…”

“…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].…”

“…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]. Therefore, new methods are needed to measure the sway frequencies of both the tree and individual branches, especially thinner branches.…”

“…The tracking methods commonly used include Pyramid Lucas-Kanade (Pyr LK) optical flow [21], dense optical flow [22] and the method based on MOSSE [23]. Wang et al [1] pointed out that the Pyr LK method and dense optical flow method are not suitable for long-term tracking of tree sway due to their sensitivity to lighting and long computation time. They proposed a method based on MOSSE for tracking tree sway under natural conditions and estimating the tree sway frequency.…”

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

“…Video recordings using a camera could also be an alternative for measuring tree motions [20,21]. However, the failure of tracking tree skeletons and lengthy processing time might hinder the application of cameras for tree vibration measurement [22]. Further, a single camera is only capable of capturing two-dimensional planar motion, which is insufficient to characterize the 3D tree motion.…”