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.

中文翻译：

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木材解剖结构对通过激光扫描五种欧洲物种获得的纤维取向测量的影响

为了获得高的锯材产量，锯木业可以使用激光扫描，以进行结点检测和机器强度分级。特别地，激光扫描仪在木材表面上使用所谓的管胞效应来测量晶粒角，在该表面上可以观察到激光的椭圆形散射。本文旨在描述通过激光束投射在木材表面上获得的光散射，并评估这种纤维取向测量在五个欧洲物种上的准确性。首先，通过旋转样品评估纤维取向测量误差。其次，在考虑椭圆轴比率和面积的情况下对散射效果进行了描述。根据几个参数进行了研究，例如木材表面加工，水分含量和正交异性对称平面。在所有被测物种上成功进行了纤维取向测量。测量误差低于1.6°，橡木纵向-径向（LR）平面误差高达3.1°。对于大多数物种，由于髓线射线的影响，在LR平面中的误差较高。尽管观察到了激光散射的主要变化，但对于所有被调查的物种，都可以以很高的精度测量晶粒角。