玉米叶片形态建模与网格简化算法研究

【目的】协调禾本科作物形态模型的可视化效果和计算效率之间的关系。【方法】提出一种利用非均匀有理B样条（NURBS）插值结合使用多直线段分裂算法（splitting）来重建玉米叶片三维形态并实现曲面网格简化控制的方法。【结果】该方法利用三维数字化仪采集的数据点，通过计算节点矢量、差值计算反求曲面控制点等步骤构造出玉米叶片曲面，具有较强地真实感效果；根据叶片形态特征，采用多直线段分裂算法的逆运算来对叶片曲面网格数量进行简化，在尽可能保持曲面特征的同时可显著降低网格数目。【结论】应用该方法进行玉米冠层可视化与光分布计算，结果表明，在不显著增大计算误差的前提下，可以明显地提高计算效率。

Maize Leaf Morphological Modeling and Mesh Simplification of Surface

The method of morphological modeling of maize leaf based on Non-Uniform Rational B-Splines (NURBS) interpolation combining with multi-line segment splitting algorithms and controllable mesh simplification of triangular surface was introduced. A group of three-dimensional data points used from a scanning device, the crop leaf crooked surface with third-dimension effect was constructed stepped by vector calculation, crooked surface control points resulted by interpolation calculation and etc. According to leaf morphological characteristic, leaf surface mesh amount was simplified by inverse operation of multi-line segment splitting algorithm, and mesh amount declined with available maintenance of surface characteristics. This method was used to calculate visualization and light distribution and the result showed that calculation effect could be improved clearly when calculation error was not increased remarkable. The method could reflect model details and provided the solution to harmonize the relation between visual effect and calculation efficiency of crop morphological model.