基于参照物和图像处理的节子大小测量方法

Measurement of wood knots using methods of reference and image processing

准确高效地测量节子大小,不仅在优选正交胶合木(CLT)原材料时可以提高出材率,达到节约成本的目的,而且对快速评价CLT的胶合性能具有重要的作用和意义。提出一种基于参照物和图像处理的节子大小测量方法:以落叶松、榉木和杨木锯材为材料,进行图像采集、图像剪裁,随后对所采集的图像进行图像灰度化、二值化处理后将规格大小的参照物进行像素标定,用OpenCV测量等进行图像处理,即可测得节子大小。所有采集数据的测量结果表明,基于参照物和图像处理的节子测量值与真实值无显著性差异,且相对误差最小为5.8%、最大为10.7%,所有试验组合中的相对误差均值为8.0%,均满足工程实际需求。这表明该方法能够准确、快速地测量节子大小。该方法可应用于测量节子大小,拓展了节子大小的测量方法,对提升节子大小计算效率具有重要意义。该测量方法运行速度快、精确度较高、鲁棒性强,可克服传统节子测量需要人工的缺点,自动化程度高,能够满足木材中节子大小测量的要求。

Under the dual pressure of scarce forest resources and rapid evaluation of gluing quality of cross-laminated Timber(CLT),accurate and efficient measurement of wood knot size would not only improve the product yield and achieve cost saving when optimizing the utilization of raw materials for CLT,but also plays significant role in rapidly evaluating gluing performance of CLT.A method of measuring knot size based on reference and image processing is proposed:image acquisition and image cropping are performed on larch,beech and poplar sawn timber,followed by image greying and binarization of the acquired images and pixel calibration of the reference of the specification size,and image processing such as OpenCV measurement to measure the knot size.The measurement results of all collected data show that there is no significant difference between the measured values of knots based on reference and image processing and the actual measured values,and the relative error is 5.8% at the minimum and 10.7% at the maximum,and the average value of relative error in all test combinations is 8.0%,which all meet the actual needs of engineering.The results indicate that this method can measure the size of knots accurately and quickly.The method can be applied not only for mea-suring knot size,but also determining the knot location,which is important for improving the efficiency of wood production.The result of this study helps to improve the evaluation system of glued wood quality and enrich the way of knot size measurement,which greatly promotes the efficiency and accuracy of knot size measurement and fits the industrial production process.The measurement method is fast,accurate and robust,and can overcome the disadvantages of traditional knot measurement,which meets the requirements of knot size measurement in wood.