In cut-to-length logging, the harvester operator adjusts the bucking in accordance with visible defects on processed stems. Some of the defects, such as a sweep on the bottom of the stem, decrease the yield and quality of sawn products and are difficult for the operator to notice. Detecting the defects with improved sensors would support the operator in his qualitative decision-making and increase value recovery of logging. Predicting the maximum bow height of the bottom log in Norway spruce ( Picea abies (L.) Karst.) with log end face image and stem taper was investigated with two modelling approaches. A total of 101 stems were selected from five clear-cut stands in southern Finland. The stems were crosscut and taper measured, and the butt ends of the bottom logs were photographed. The stem diameter, out-of-roundness, and pith eccentricity were measured from the images while the max. bow height was measured by a 3D log scanner at a sawmill. The bottom logs with an eccentric pith had higher max. bow height. In addition, a highly conical bottom part of the stem was more common on the bottom logs with a large max. bow height. Applying both log end face image and stem taper measurements gave the best model fit and detection accuracy (76%) for bottom logs with a large max. bow height. The results indicate that the log end face image and stem taper measurements can be utilised to aid harvester operator in deciding an optimised length for logs according to the bow height.

中文翻译：

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原木端面图像和茎锥度表明挪威云杉底部原木的最大弓高

在定长切割伐木中，收割机操作员根据加工过的茎上的可见缺陷调整屈曲度。一些缺陷，例如杆底部的扫掠，会降低锯材的产量和质量，并且操作员很难注意到。使用改进的传感器检测缺陷将支持操作员的定性决策并增加测井的价值恢复。使用两种建模方法研究了使用原木端面图像和茎锥度预测挪威云杉 ( Picea abies (L.) Karst.) 底部原木的最大弓高。共有 101 根茎从芬兰南部的 5 个砍伐林分中挑选出来。将茎横切并测量锥度，并拍摄底部原木的对接端。阀杆直径、不圆度、和髓偏心是从图像中测量的，而最大值。船首高度由锯木厂的 3D 原木扫描仪测量。具有偏心髓的底部原木具有更高的最大值。弓高。此外，在最大最大的底部原木上，茎的高度锥形底部更常见。弓高。应用原木端面图像和茎锥度测量为具有较大最大值的底部原木提供了最佳模型拟合和检测精度 (76%)。弓高。结果表明，原木端面图像和茎锥度测量可用于帮助收割机操作员根据弓高决定原木的优化长度。茎的高度锥形底部在最大最大的底部原木上更为常见。弓高。应用原木端面图像和茎锥度测量为具有较大最大值的底部原木提供了最佳模型拟合和检测精度 (76%)。弓高。结果表明，原木端面图像和茎锥度测量可用于帮助收割机操作员根据弓高决定原木的优化长度。茎的高度锥形底部在最大最大的底部原木上更为常见。弓高。应用原木端面图像和茎锥度测量为具有较大最大值的底部原木提供了最佳模型拟合和检测精度 (76%)。弓高。结果表明，原木端面图像和茎锥度测量可用于帮助收割机操作员根据弓高决定原木的优化长度。