手杖式测树仪立木树高量测研究

Study on tree height measurement based on stick-type tree measuring instrument

【目的】树高是森林经营决策中最重要的一个参量,常用于估计森林生长、年龄、材积、生物量和碳储量等立木参数,其精度对立木质量的评价及森林生长的预测分析影响重大。为解决传统的树高量测仪器移动不便,测量周期长,人力耗损大等问题。【方法】以近景摄影测量为基础,构建了一种以登山杖绑定安卓智能手机为测量平台的便携、快捷的树高测量装备;针对立木生长环境有无坡度,拍摄是否产生倾角等情况建立了树高量测模型。在手机环境下,研制了立木树高测量软件APP。APP采用上下分屏技术,利用手机成像系统以及坐标系转换,使屏幕与待测立木建立关联,从而自动解算立木的深度信息;结合手机内部方向传感器的强大性能,单站作业可实时获取树高估计值。在北京市平谷区红石门村选取不同坡度的307株立木作为研究对象,使用该装备分别在上坡位和下坡位对其进行量测,将测定结果与全站仪多次量测求得的平均值进行对比分析。【结果】结果表明,树高估计值平均绝对误差为0.21 m,平均相对误差为2.11%,整体精度达到97.89%。当处于下坡位观测时,树高估计值平均绝对误差为0.11 m,平均相对误差为1.16%,树高精度高达98.84%。当处于上坡位观测时,树高估计值平均绝对误差为0.32 m,平均相对误差为3.07%,树高精度达到96.93%。智能手机倾斜角较大时,精度达到95.19%,智能手机倾斜角较小时,精度高达99.03%,说明手杖式测树仪观测时所产生倾角越小,精度越高。量测同一株立木时,下坡位观测的精度优于上坡位。【结论】此装备的研发满足国家森林资源连续清查中的测量精度要求,且装备成本低、灵活性强、不依赖其他设备获取深度信息、携带方便、具有较高利用价值,未来可作为森林资源调查树高测量装备。

【Objective】Tree height is one of the most important parameters in forest management decision-making.It is often used to estimate tree parameters such as forest growth,age,volume,biomass and carbon storage.Its accuracy has a significant impact on the evaluation of tree quality and the prediction and analysis of forest growth.In order to solve the problems such as inconvenient moving,long measuring period and large manpower consumption of traditional tree height measuring instrument.【Method】On the basis of close range photogrammetry,this study constructed a portable and fast tree height measurement equipment based on the combination of climbing stick and Android smart phone.According to whether there is slope in the growing environment and whether there is dip angle in the shooting,the measurement model of tree height is established.Under the environment of mobile phone,the software app for measuring the height of tree is developed.It uses up and down split screen technology,mobile phone imaging system and coordinate system conversion to associate the screen and tree,so as to automatically calculate the depth information of tree.Combined with the powerful performance of the direction sensor inside the mobile phone,the tree height estimation can be obtained in real time by single station operation.In Hongshimen village,Pinggu district,Beijing,307 trees with different slopes were selected as the research objects.The equipment was used to measure them at the up slope and down slope respectively,and the results were compared with the average values obtained by the total station.【Result】The average absolute error of tree height estimation is 0.21 m,the average relative error is 2.11%and the overall accuracy is 97.89%.When it is in the downhill position,the average absolute error of tree height is 0.11 m,the average relative error is 1.16%,and the accuracy of tree height is 98.84%.When it is in the uphill position,the average absolute error of tree height estimation is 0.32 m,the average relative error is 3.07%,and the accuracy of tree height reaches 96.93%.When the tilt angle of smart phone is large,the accuracy reaches 95.19%,and when the tilt angle of smart phone is small,the accuracy reaches 99.03%.This shows that the smaller the tilt angle produced by stick-type tree measuring instrument is,the higher the accuracy is.When measuring the same tree,the accuracy of downhill position observation is better than that of uphill position.【Conclusion】The research and development of this equipment can meet the measurement accuracy requirements of the national forest resources continuous inventory,and the equipment has low cost,strong flexibility,does not rely on other equipment to obtain depth information,is convenient to carry,and has high utilization value.It can be used as the height measurement equipment of forest resources investigation tree in the future.