Measurement of Individual Tree Parameters with Carriage-Based Laser Scanning in Cable Yarding Operations

Abstract

Introduction: Cable yarding is a technology that enables efficient and sustainable use of timber resources in mountainous areas. Carriages as an integral component of cable yarding systems have undergone significant development in recent decades. In addition to mechanical and functional developments, carriages are increasingly used as carrier platforms for various sensors. The goal of this study was to assess the accuracy of individual standing tree and stand variable estimates obtained by a mobile laser scanning system mounted on a cable yarder carriage.Methods: Eight cable corridors were scanned across two forest stands. Four different scan variants were conducted, differing in the movement speed of the carriage and the direction of movement during scanning. An algorithm for tree detection, diameter and height estimation was applied to the 3D datasets and evaluated against manual tree measurements.Results: The analysis of the 3D scans showed that the individual tree parameters strongly depend on the scan variant and the distance of each individual tree to the skyline. This was due to changing 3D point densities and occlusion effects. It turned out that scan variant 1, in which the scan was performed during slow carriage movement downwards and back upwards again, was advantageous. At a distance of 10 m, which is half of the recommended corridor spacing of 20 m for whole tree cable yarding, 95.44% of the trees in stand 1 and 92.16% of the trees in stand 2 could be detected automatically. The corresponding root mean sqare errors of the diameter at breast height estimatimations were 1.59 cm and 2.23 cm, respectively. The root mean square errors of the height measurements were 2.94 m and 4.63 m.Conclusions: The results of this study can help to further advance the digitization of cable yarding and timber flow from the standing tree to the sawmill. However, this requires further development steps in cable yarder, carriage, and laserscanner technology. Furthermore, there is also a need for more efficient software routines to take the next steps towards precision forestry.

Sensors for Digital Transformation in Smart Forestry

“…In the realm of operational autonomy, sophisticated sensor technology is indispensable. For instance, LiDAR (Light Detection and Ranging) is instrumental in mapping forest topography, assessing biomass, and monitoring forest health, providing high-resolution 3D data for the precise measurements of tree height, canopy structure, terrain features and helping in the digital transformation of cable yarding for sustainable timber harvesting [17]. Similarly, multispectral and hyperspectral imaging plays a crucial role in monitoring vegetation health, species identification, and detecting changes in forest cover, capturing data across various wavelengths to reveal insights into plant health and ecological parameters.…”

Mobile Laser Scanning Data Collected under a Forest Canopy with GNSS/INS-Positioned Systems: Possibilities of Processability Improvements

“…Nowadays, attention is mainly focused on moving (mobile) applications that concern vehicles, backpacks [21][22][23][24], and handheld or personal devices [2,13,[25][26][27], including mobile phones [28][29][30][31]. Logging machines represent specific applications [32][33][34], including skyline equipment [35,36], for tree parameter measurement.…”