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以烟草冠层为例,使用面向对象技术,设计虚拟传感器,以改进蒙特卡罗光线跟踪模型,获得冠层中任意位置的截光率,进而定量分析各参数对模拟结果的影响。试验结果表明:1)初始光线投放密度和冠层结构精度对模型计算结果影响较大;2)在其他参数条件不变时,增加模型跟踪深度,增大天空散射源分布密度将提高模型计算精度。最后,对比了相同时段同一烟草冠层的田间实验和模型计算得到的光合有效辐射三维空间分布,决定系数(R2)达0.98。该研究结果可为蒙特卡罗光线跟踪模型在作物冠层光分布模拟应用中提供参考依据。
Taking the tobacco canopy as an example, an object-oriented technique was used to design a virtual sensor to improve the Monte Carlo ray tracing model and get the cut-off rate at any position in the canopy. Then the influence of each parameter on the simulation results was quantitatively analyzed. The experimental results show that: 1) the initial light flux density and canopy structure accuracy have a great influence on the model calculation results; 2) increasing the model tracking depth and increasing the distribution density of sky scattering sources will improve the model calculation accuracy . Finally, the three-dimensional spatial distribution of photosynthetically active radiation calculated from field experiments and models of the same tobacco canopy at the same time period was compared and the determination coefficient (R2) was 0.98. The results of this study can provide reference for the application of Monte Carlo ray tracing model in crop canopy light simulation.