落叶松林分生长枝条躲让效应计算机模拟研究
摘要
华北落叶松是华北地区主要造林树种,具有速生、丰产、材质好等特点。但在其生长规律的研究中,由于周期较长,林木形态结构复杂,环境条件难以控制,表现为显著的区域性和时空变异性,使得难以综合考虑其多因子互作、预测其生长趋势、量化管理措施。本文以华北落叶松生理生态学理论为依据,基于河北省塞罕坝机械林场的实测单木形态基本数据,采用遗传规划算法,建立了落叶松胸径和树高理论生长方程,采用层次包围盒方法沿坐标轴包围盒检测碰撞原理,进行了落叶松枝条碰撞检测,给出了落叶松枝条躲让效应的算法及其伪代码,编程实现了枝条躲让效应的动态模拟,并以两根起点在同一水平但不同生长速率的枝条碰撞为例,验证了枝条躲让的运动过程。
在林分平均胸径和树高模型中增加了立地指数和植林密度因素,采用遗传规划进行数据拟合。遗传规划不依赖问题域,无需对输入的数据进行预处理,可避免过早地陷入局部最优群体现象,不依赖梯度信息,使得收敛速率加快,模型表达简单、精度高、适用范围广。落叶松植林密度是影响森林生长量和林木质量的重要因素,林分过密会影响林木径生长,争夺阳光养份会造成偏冠,同时树冠下部枝条由于通风透光不良易慢慢死亡,在木材上形成大的节疤;林分过稀会使树木削度大,影响出材量和公顷蓄积量,造成林地浪费。本文将树枝的躲让效应分为碰撞检测和实体移动两部分,对枝条碰撞检测算法采用层次包围盒法,可尽可能减少基本几何元素对的数目。结果认为落叶松枝条碰撞后自然向上偏移极小角度形成躲让效应,从而得到落叶松枝条躲让效应的算法及其伪代码。文中分析了树干、枝、叶、叶丛及球果等拓扑结构并给出了华北落叶松形态结构参数表。采用L-系统进行可视化编程,选用基于图改写的软件实现工具L-studio作为实现工具,编写了枝条躲让效应的动态模拟软件。
随着信息技术的发展,数字林业正在崛起,用数字化技术重塑现代林业,将从根本上改变林业传统落后的面貌,有力地推动林业增长方式转变和林业生产与林业经济结构调整优化,对大力发展林业,解决我国木材日趋尖锐的供需矛盾以及改善人类生存环境质量具有重要意义。
Larix Principis-rupprechtii Mayr is the main tree species of north China, which has many characteristics such as fast-growing, high yield, material quality and so on.But in its study of growth pattern, because of Longer cycle, trees form the structure of complex, difficult to control environmental conditions, growth pattern showed significant regional and temporal and spatial variability, so it is hard to consider multi-factor interaction, forecast growth trend and quantitative management. The paper has physiology and ecology theory of Larix Principis-rupprechtii Mayr as basis, according to the integration of observed morphological structural data from Hebei Saihanba Forest Farm, use the Genetic Programming to simulate, and get the better theoretical stand mean diameter at breast height and stand mean tree height growth functions, Adopt the theory of Collision Detection by the axis-aligned bounding boxes method of hierachical bounding boxes detect branches collision. We consider as branches will spontaneously move up a teeny angle after collision, and get arithmetic of shyness effect and pseudocode and according to algorithm of the shyness effect write environment procedures code to simulate the shyness effect, and with two branches which have same level and different growth rate, we test the algorithm of the shyness effect.
We add another two factors Site Index and Afforestation Density to the growth functions in the stand mean diameter at breast height and stand mean tree height growth functions of Larix Principis-rupprechtii Mayr, use the Genetic Programming to simulate. Genetic Programming does not rely on problem domain, not pre-process data, avoid the premature phenomenon of a group of local optimum and not rely on gradient information, that speeds up the convergence rate and the models are simple expression, high-accuracy and wide-applicable. Density of tree is an important factor to impact of forest growth and wood quality, too dense stand of tree will affect the growth of diameter, competition for nutrients will cause the sun partial crown, and at same time the lower crown branches will slowly died because of bad ventilation and light, form the scars in timber; Too sparse stand of tree will make big taper of trees, affect timber volume and hectares of volume, and caused forest waste. The paper divided the shyness effect of branches into collision detection and mobile entities, we use the hierachical bounding boxes to detect collision, which can reduce the number of basic geometric elements as much as possible. We consider that branchers will move upon a very small angle after collision, and get arithmetic of shyness effect and pseudocode. The paper also analyzes the geometrical and topological structures of the whole tree, branche, leaf, leaf bunches and cone, and get the table of morphological structural parameters. We write visual programming by L-system, selecte L-studio which base on graph rewriting as a tool to get the dynamic simulation software branches shyness effects.
With the development of information technology, digital forestry is rising. Remodeling modern forestry with digital technology will fundamentally change the tradition and backward, effectively promote the growth patterns of forestry, and adjust and optimize forestry production and the economic structure of forestry. It has great significance to vigorously develop the forestry, solve China's timber sharp contradiction between supply and demand, and improve the environmental quality of human existence.
在林分平均胸径和树高模型中增加了立地指数和植林密度因素,采用遗传规划进行数据拟合。遗传规划不依赖问题域,无需对输入的数据进行预处理,可避免过早地陷入局部最优群体现象,不依赖梯度信息,使得收敛速率加快,模型表达简单、精度高、适用范围广。落叶松植林密度是影响森林生长量和林木质量的重要因素,林分过密会影响林木径生长,争夺阳光养份会造成偏冠,同时树冠下部枝条由于通风透光不良易慢慢死亡,在木材上形成大的节疤;林分过稀会使树木削度大,影响出材量和公顷蓄积量,造成林地浪费。本文将树枝的躲让效应分为碰撞检测和实体移动两部分,对枝条碰撞检测算法采用层次包围盒法,可尽可能减少基本几何元素对的数目。结果认为落叶松枝条碰撞后自然向上偏移极小角度形成躲让效应,从而得到落叶松枝条躲让效应的算法及其伪代码。文中分析了树干、枝、叶、叶丛及球果等拓扑结构并给出了华北落叶松形态结构参数表。采用L-系统进行可视化编程,选用基于图改写的软件实现工具L-studio作为实现工具,编写了枝条躲让效应的动态模拟软件。
随着信息技术的发展,数字林业正在崛起,用数字化技术重塑现代林业,将从根本上改变林业传统落后的面貌,有力地推动林业增长方式转变和林业生产与林业经济结构调整优化,对大力发展林业,解决我国木材日趋尖锐的供需矛盾以及改善人类生存环境质量具有重要意义。
Larix Principis-rupprechtii Mayr is the main tree species of north China, which has many characteristics such as fast-growing, high yield, material quality and so on.But in its study of growth pattern, because of Longer cycle, trees form the structure of complex, difficult to control environmental conditions, growth pattern showed significant regional and temporal and spatial variability, so it is hard to consider multi-factor interaction, forecast growth trend and quantitative management. The paper has physiology and ecology theory of Larix Principis-rupprechtii Mayr as basis, according to the integration of observed morphological structural data from Hebei Saihanba Forest Farm, use the Genetic Programming to simulate, and get the better theoretical stand mean diameter at breast height and stand mean tree height growth functions, Adopt the theory of Collision Detection by the axis-aligned bounding boxes method of hierachical bounding boxes detect branches collision. We consider as branches will spontaneously move up a teeny angle after collision, and get arithmetic of shyness effect and pseudocode and according to algorithm of the shyness effect write environment procedures code to simulate the shyness effect, and with two branches which have same level and different growth rate, we test the algorithm of the shyness effect.
We add another two factors Site Index and Afforestation Density to the growth functions in the stand mean diameter at breast height and stand mean tree height growth functions of Larix Principis-rupprechtii Mayr, use the Genetic Programming to simulate. Genetic Programming does not rely on problem domain, not pre-process data, avoid the premature phenomenon of a group of local optimum and not rely on gradient information, that speeds up the convergence rate and the models are simple expression, high-accuracy and wide-applicable. Density of tree is an important factor to impact of forest growth and wood quality, too dense stand of tree will affect the growth of diameter, competition for nutrients will cause the sun partial crown, and at same time the lower crown branches will slowly died because of bad ventilation and light, form the scars in timber; Too sparse stand of tree will make big taper of trees, affect timber volume and hectares of volume, and caused forest waste. The paper divided the shyness effect of branches into collision detection and mobile entities, we use the hierachical bounding boxes to detect collision, which can reduce the number of basic geometric elements as much as possible. We consider that branchers will move upon a very small angle after collision, and get arithmetic of shyness effect and pseudocode. The paper also analyzes the geometrical and topological structures of the whole tree, branche, leaf, leaf bunches and cone, and get the table of morphological structural parameters. We write visual programming by L-system, selecte L-studio which base on graph rewriting as a tool to get the dynamic simulation software branches shyness effects.
With the development of information technology, digital forestry is rising. Remodeling modern forestry with digital technology will fundamentally change the tradition and backward, effectively promote the growth patterns of forestry, and adjust and optimize forestry production and the economic structure of forestry. It has great significance to vigorously develop the forestry, solve China's timber sharp contradiction between supply and demand, and improve the environmental quality of human existence.
引文
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