LOD技术在动车组虚拟现实系统开发中的应用

Application of level of detail technology in the virtual reality system of electric multiple units

多细节层次模型(LOD)技术已广泛应用于计算机仿真、虚拟现实等多个领域。动车组虚拟现实系统中,由于复杂模型零件个数众多,结构复杂,为了尽可能展示逼真的虚拟场景,运用LOD理念进行模型简化具有重要意义。现有的研究成果多着眼于模型网格和纹理结构的简化,较少考虑模型本身所具有的外部形状特征。本文提出了一种分步式模型简化算法,先通过简化的边折叠方法进行预处理,再运用基于包围盒的AABB算法进一步简化,并且通过引入阈值来控制生成不同精度的模型。实验证明,处理后的模型不但达到了较高的简化率,而且具有较高的真实感。

Level of detail （ LOD） technology is widely used in computer simulation, virtual reality and other fields. In the virtual reality system of electric multiple units （ EMUs） , complex models with complex structures have many spare parts, so simplifying the model by LOD technology is important in showing realistic virtual scenes. Most of re-searches currently only focus on simplifying the grid and texture of the model while ignoring the characteristics of the external shape of the model. In this paper, a method to simplify models by fractional steps is proposed. This method contains two steps as follows：the first step is to preprocess the model by the edge collapse method;the sec-ond step is to use the axis-aligned bounding box （ AABB） algorithm based on bounding box to do further simplifica-tion. Different precision models are generated by the introduction of thresholds. The experiment results show that the model which has been processed not only achieves a high simplification rate, but also has high fidelity.