树木年轮信息解析系统研制与试验

    Development and experiments of a tree ring information analysis system

    • 摘要: 树木年轮信息在树木年代学、气候学、生态学、灾害学和环境学等领域研究中有重要的作用。为准确、快速、地获取树木年轮信息,降低工作强度和操作复杂度,该研究设计了一种树木年轮信息解析系统。该系统在硬件上进行了机电一体化设计,主要包含滑台模组、旋转编码器、步进电机、置物台、手轮、工业相机、控制箱、光学显微镜、电脑等组件,基于C#语言和OpenCvSharp工具包设计上位机,所设计的上位机软件通过与工业相机、采集器和控制器通信来实现对年轮信息采集、处理和存储,实现位置计算、电机控制和图像识别。系统设计了2种方法进行年轮信息解析:1) 电子显微定位法。在常规显微定位法的基础上,基于旋转编码器和螺旋测距法感知滑台线性位移进而实现年轮宽度测量,并使用工业相机和显示器代替传统显微镜来判读年轮线,最后可生成年轮解析图表;2)图机辅助法。在电子显微法的基础上,结合图像识别与电机控制算法进行改进。为验证系统的年轮宽度测量精度、年轮线识别准确率和解析效率,以传统显微镜和光学标定板作为参照工具,采集油松、落叶松、杨树、白桦4个树种的木芯样品进行试验。试验结果表明:在年轮宽度测量精度上,电子显微定位法和图机辅助法的平均绝对误差分别为5.68和7.84 μm,均方根误差分别为6.31和8.62 μm,满足国家标准;在年轮线识别上,油松、落叶松、杨树、白桦4个树种的准确率分别为83.3%、93.7%、55.0%和68.3%,针叶树种组、阔叶树种组的平均召回率分别为96.4%和72.6%,能够辅助判读年轮线;在解析效率上,平均每个年轮采集耗时为电子显微定位法1.58 s、图机辅助定位法1.24 s,分别比显微定位法提高了约19%和36%。综合而言,该系统实用性强、精度高、效率高,工作疲劳度低、成本低(<1万元),在多个学科领域中具有推广应用前景。

       

      Abstract: Abstract: Tree ring information dominates in dendrochronology, climatology, ecology, disaster, and environmental science. This study aims to accurately and rapidly obtain the tree ring information, particularly with the low labor intensity and simple operation. An analysis system was also designed for the tree annual ring information. The electro-mechanical design integrated with the hardware of the system, including a slide table module, a rotary encoder, a stepper motor, a shelf table, a hand wheel, two limiters, an industrial camera, an optical microscope, a computer and components, as well as the control boxes (integrated with self-designed collector and controller circuits). The upper computer software of the system was designed to communicate with the industrial camera, collector, and controller using C# language and OpenCvSharp toolkit. The annual information was then collected, processed, and stored in this case. The position calculation, motor control and image recognition were also utilized to design the image recognition using gray component and gray projection analysis. Two methods were designed for the tree ring information analysis in this system: 1) Electronic micro-position method. The spiral ranging method was utilized to measure the linear displacement of the sliding table using the rotary encoder and the collector. The tree ring line was then observed using the industrial camera instead of the traditional microscope. 2) Graph-motor assisted method. The electronic micro-position method was used to combine image recognition and stepper motor control. A field test was carried out to verify the measured tree ring width, the identified tree ring line, and the performance of the analysis system, compared with the traditional microscopes and optical calibration plate. Taking the Chinese pine, larch, poplar, and birch as the research objects, the wood cores of four tree species were collected as the tree ring samples for testing. The test results showed: firstly, the electronic micro-position method performed a 5.68 μm mean absolute error (MAE) and a 6.31 μm root mean square error (RMSE), whereas, the MAE and RMSE of the graph-motor assisted method was 7.84 and 8.62 μm respectivly, which was fully met the National Standards in China; secondly, the accuracy rates of the identification of tree ring line for Chinese pine, larch, poplar and birch species were 83.3%, 93.7%, 55.0%, and 68.3% respectively, and the average recall rates of identification of tree ring line for the coniferous and broad-leaved species group were 96.4%, and 72.6%, respectively, indicating the better performance to identify the annual ring line; thirdly, the average collection time of each tree ring was 1.58 s for the electronic micro-position method, while 1.24 s was for the graph-motor assisted method, which were about 19% and 36% more efficient than the conventional microscopic positioning method, respectively. In conclusion, the improved system presented strong practicability, high accuracy, high efficiency, low working fatigue, and low cost (less than 10 000 Yuan). Therefore, the information system of tree rings can also be expected to promote broad application prospects in multiple subject areas.

       

    /

    返回文章
    返回