基于OSG数字林分景观可视化技术研究

大规模林分场景建模和实时绘制对于模拟林分生长具有重要意义。本文定义了一个基于树龄分枝的树木表达模型，该模型可构建形态结构不规则、灵活的树木模型；在林分场景绘制中，提出了一种基于OSG大规模林分场景的实时绘制技术，利用存储在XML文件中真实的林分调查数据可以实时绘制三维林分场景。林分树木场景数据量大，为了提高场景渲染的效率，利用OSG场景图来组织和优化场景数据；在林分单元格的绘制中引入3D树木的LOD网格简化和PageLOD数据库分页机制实现大规模数据调度。实例证明，所绘制的大规模林分场景能满足用户的实时交互需求。 

Real-time rendering of large-scale forest scene based on OSG and GPU

It is a challenging work for stand growth simulation to render a large-scale forest scene in real time. In this paper, we present a hybrid rendering technology of large-scale forest scene based on OpenSceneGraph (OSG) and GPU. The realistic forest scene can be rendered according to the data of stands, which was stored in a XML file. A tree rendering model was described based on tree growth, which was composed of tree trunk, branch and leaves. In tree modeling, we can define different years of tree by using different layers of tree branch. An OSG scene management graph was used to organize and optimize the complicated virtual scene. In order to improve the interactive frame rates, a view-dependent LOD 3D model simplification algorithm and a PageLOD paging mechanism were proposed to achieve large-scale forestry data scheduling. Finally, the technique is proved to be valid in real-time rendering of large scale forest scene.