基于OpenGL的交互式三维树木建模与可视化研究

Research on interactively 3D tree modeling and visualization based on OpenGL

通过讨论树体枝干几何建模的理论和方法,重点围绕树木交互式建模技术和三维可视化实现进行了研究探讨。实现过程主要分为3步:首先,对真实树木枝干的几何形态结构进行分析,利用分析结果构建枝干模型生成方法,用六边形棱柱近似模拟树干和枝段,再用六边形棱台作为枝段元经过连续偏转、连接的方法模拟枝干弯曲的形态。其次,基于枝干生成方法,利用分形迭代思想实现整株树体的建模。为提高仿真度,通过加入干扰因子使最终生成的树体枝干模型不过于规则。最后,为实现模型的可视化,选用OpenGL图形技术和Visual C++作为模型可视化工具和开发工具,通过对所建立的模型进行数学描述以及场景渲染和特征参数提取,建立一个支持交互的三维树木建模系统。

To discuss the theory and methodology of geometrical modeling for a tree and research on interactive modeling and 3D visualization technology,a three-step realization process was established.Results of model development were as follows:Firstly,the geometric structure of real branches was analyzed to construct a generation method for the branch model,and a hexagonal prism was proposed to represent the trunk or branch.The curved shape was realized by using segment elements through continuous deflection and connection.Secondly,based on the generation method for a branch,the whole tree was constructed by a fractal iterative method.To improve the degree of simulation,interference factors were added to make the final stem model not too regular.Finally,the OpenGL graphics technology and Visual C++ were chosen as visualization and development tools.Thus,the modeling system of 3D trees supporting interaction was constructed by a mathematical description of the tree model,a rendering of the scene and a extracting of the feature parameters.[Ch,11 fig.3 tab.13 ref.].