Influence of wood anatomy on fiber orientation measurement obtained by laser scanning on five European species

Abstract

In order to obtain high production rates of sawn timber, the sawmilling industry can use laser scanning, allowing knot detection and machine strength grading. In particular, laser scanners measure grain angle using the so-called tracheid effect on wood surface where an elliptic scattering of the laser light can be observed. This paper aims to describe the light scattering obtained by a laser beam projection on wood surface and to assess the accuracy of such fiber orientation measurement on five European species. Firstly, fiber orientation measurement error was assessed by rotating samples. Secondly, the description of the scattering effect was done considering ellipse axis ratios and areas. This was studied according to several parameters such as wood surface machining, moisture content, and orthotropic planes of symmetry. Fiber orientation measurement was successfully performed on all the tested species. The measurement error was below 1.6°, except for oak longitudinal–radial (LR) plane showing an error up to 3.1°. For most of the species, the error was higher in LR plane because of the influence of medullary rays. Despite the observation of major variabilities in laser light scattering, it was possible to measure the grain angles with a good accuracy for all investigated species.

Predicting the strength of European beech (Fagus sylvatica L.) boards using image-based local fibre direction data

“…The tracheid effect has been used to improve the strength grading of coniferous timber (Brännström et al, 2008;Olsson et al, 2013;Olsson and Oscarsson, 2017;Viguier et al, 2015Viguier et al, , 2017. More recently it has also been applied successfully to fibre orientation measurements on hardwoods (Besseau et al, 2020), on beech veneers to estimate the modulus of elasticity of LVL (Viguier et al 2018), and to strength grading of oak (Olsson et al, 2018).…”

Traceability and quality assessment of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) logs: the TreeTrace_Douglas database

“…Then, these data were post-processed and the contours were fitted to an ellipse equation in the least square sense. The reader can refer to Besseau et al (2020) for more details about this subject. The post-processing step provides for each ellipse, in each laserDotTop, laserDotBot, laserDotLeft, and laserDotRight table:…”

Grain angle determination of silver birch by laser light scattering and tensile fracturing

“…Literature investigating laser scattering on various hardwood species show that the grain direction of hardwoods can be effectively measured, e.g. [23][24][25][26][27][28], albeit, the laser scattering behaviour can be rather different between species [22,24,28], requiring species level optimization.…”