【作者】 李洲；

【导师】 王卫红；

【作者基本信息】 浙江工业大学 ， 计算机软件与理论， 2008， 硕士

【摘要】 西部高原复杂的地形地貌和恶劣多变的气象条件,使得高原机场对飞行员的技能要求远远高于其他普通机场,而飞行模拟器也已成为训练飞行员不可缺少的设备。随着遥感和虚拟现实等技术日的趋成熟,模拟器对视景的逼真度要求越来越高,海量高程、影像数据同有限硬件资源之间的矛盾也越来越突出,而传统的地形可视化方法已无法满足大范围高分辨率视景仿真所带来的大数据量处理方面的实时性能要求。本文以民用航空飞行仿真和大规模地形可视化为研究背景,首先根据高原复杂机场地形场景的特殊性,提出了一种基于非正方形四叉树分层分块的地形金字塔建模方法,并结合MRLoD技术来构建大规模多分辨率地形模型。针对本文的四叉树地形金字塔模型,分别提出了基于TRN和TIN的分块地形几何建模方法及其相应的多分辨率分块接边裂缝消除方法,并最终采用TIN作为本文原型系统的几何建模方法。同时配合几何模型,提出了一种基于多分辨率纹理四叉树的纹理组织及映射方法,进一步提高真实感地形的渲染速度。在实时渲染技术中,基于本文的四叉树地形金字塔模型,提出了一种分块可见性判断、分辨率计算及调度的方法,并通过分块预测算法来平滑漫游效果,在保持地形模型精度的同时有效地降低视景内模型的数据量和复杂性。最后在上述技术理论的研究基础上,对高原机场视景仿真原型系统进行了设计,并基于OpenGL实现了原型系统。通过对实验结果的描述和分析,显示了本文所提出的大规模地形建模及实时渲染方法的有效性。更多还原

【Abstract】 The pilot skills which required by the altiplano aerodromes are much higher than by the other aerodromes due to the complex terrain environment and atrocious weather conditions of the western altiplano, moreover, flight simulator has been indispensable to pilot training. As the development of remote-sensing and virtual-reality technologies, higher scene fidelity is required by the simulator, meanwhile it brings the conflict between massive elevation/image data and limited hardware resources. However, the traditional methods of terrain visualization can’t satisfy the real-time requirement of massive data processing according to large-scale high-resolution scene simulation.In this thesis, with the research background of civil aviation flight simulation and large-scale terrain visualization, a method of terrain pyramid modeling based on non-square layered-and-tiled quad-tree is proposed. It builds the large-scale multi-resolution terrain model by integrating MRLoD technique.Methods of geometry modeling of tiled terrain which based on TRN and TIN respectively is proposed for the terrain quad-tree pyramid model, and methods of avoiding gaps of multi-resolution tiles are also proposed corresponding to the geometry modeling method. The ultimately method of the thesis is based on TIN. Then a method of texture mapping based on multi-resolution texture quad-tree is proposed to cooperate with the geometry model. It further improves the speed of living terrain rendering.For real-time rendering, methods of visibility judgment, resolution computing and scheduling of tiles are proposed based on the terrain quad-tree pyramid model, and an algorithm of tile prediction is used to smooth the rendering effects. These methods effectively simplify the models within the scene while keeping their precision.Finally, based on the researches of technology theories above, the Prototype System of Scene Simulation of Altiplano Aerodrome is designed and implemented using OpenGL. The experimental results show the validity of methods of large-scale terrain modeling and real-time rendering which proposed by the thesis.更多还原