论文部分内容阅读
树木的三维建模是建立虚拟森林环境的关键问题之一。基于树木形态结构特征分析,提出了面向对象的矢栅混合模型,并详细描述了主干、枝段、枝条和树叶之间的五组拓扑关系。结合L-system s和三维几何结构方法的优势,提出规则和约束的三维树木建模方法,该方法将分枝策略和叶片空间分布特征转化为规则,利用参数化L-system s实现,建模时将树木的空间几何特征和拓扑关系赋予树木模型,所建模型符合树木的生物物理特征。建模过程中通过阈值、模型调整和随机值约束,对模型参数进行控制,约束的内容包括树木结构、单叶尺寸、叶面积指数、随机性四个方面。最后,利用VC++与OpenGL实现了数据模型与建模算法,并利用实测数据进行了验证,所得模型比其他模型更符合于树木实际的形态结构参数和生物物理指标,有利于实现与树木空间结构相关的定性和定量分析。
Three-dimensional modeling of trees is one of the key issues in establishing a virtual forest environment. Based on the analysis of morphological features of trees, an object-oriented raster-mix model was proposed and five topological relations between trunk, branch, branches and leaves were described in detail. Combining the advantages of L-system and 3D geometry method, a three-dimensional tree modeling method based on rules and constraints is proposed. The method transforms the branching strategy and the spatial distribution characteristics of leaves into rules, using the parametric L-system implementation, modeling When the spatial geometry and topological relations of trees are given to the tree model, the model is in accordance with the biophysical characteristics of the tree. During the modeling process, the model parameters are controlled by threshold, model adjustment and random value constraints. The constraints include four aspects: tree structure, leaf size, leaf area index and randomness. Finally, the data model and the modeling algorithm are implemented by using VC ++ and OpenGL, and verified with the measured data. The obtained model is more in line with the actual morphological parameters and the biophysical indexes of the trees than other models, which is in favor of the relationship with the spatial structure of the trees Qualitative and quantitative analysis.