Abstract: Owning to the high precision requirement of tree model and the large amount of calculation with canopy radiation simulation, a new method which is a suitable mesh simplification of blade model based on method of edge collapse is proposed. On the base of QEM simplification algorithm, a method of changing the order of edge collapses in the simplification is presented by introducing the curvature change and irregular triangle judgment into the error metrics, using half-edge collapse to keep blade model boundary. Taking loquats as an example, getting the 3D loquats’ blade  model by hand-held laser scanner Artec Eva, simplify the blade model by this new method, and apply the simplified blade model to the radiation calculation. In the aspect of simulation precision of the radiation, the experimental results show that the simulation results of the same model between before and after simplification have small variations. The simplified method can meet the requirement of the?radiation simulation accuracy, and improve the calculation efficiency of radiation simulation significantly; In the aspect of visualization effects, the simplified model can keep the main morphological structure characteristics of blades and get a well visualization effect.

Key words: mesh simplification, edge collapse, vertex normal, Photosynthetically Available Radiation（PAR） distribution simulation

摘要： 针对冠层辐射模拟对模型精度要求高，而计算量大的问题，提出了一种适应于叶片模型网格简化的改进边折叠方法。在基于二次误差测度算法的基础上，在折叠代价中引入曲率变化及狭长三角形的判断，同时对于叶片模型边界的保持则采用半边折叠的方法。以枇杷为例，利用Artec手持激光扫描仪获取的叶片网格模型进行简化，并将简化后的叶片模型应用到辐射度计算，实验结果表明，在辐射度的模拟精度方面，相同模型简化前后的模拟结果变化幅度较小，可以满足辐射度模拟精度要求，而明显提高辐射度的计算效率；在可视化效果方面，简化后的模型能够保持叶片的主要形态结构特征，有着较好的可视化效果。

关键词: 网格简化, 边折叠, 顶点法向, 光合有效辐射（PAR）分布模拟