一种粗精度三维模型的生成与快速显示方法

为了解决用传统方法简化后的复杂三维模型表面存在的裂缝，纹理拉伸、缺失、错位等严重影响模型视觉效果的问题，本文提出一种粗精度模型的生成与快速显示方法，该方法利用Billboard作为模型的载体，利用GPU技术实现Billboard随视点的旋转功能，利用视点和Billboard之间的角度动态地更换相应的纹理图片。实验表明，从远处看，用该方法生成的Billboard与原始模型相差无几，完全可以用Billboard替代原始模型，从近处看，用Billboard替代的模型有细微的几何畸变。因此，该方法适合LOD较粗级别的显示，特别是对于拥有大数据量的数字城市和数字地球系统，其不仅保证了远处模型的视觉效果，而且还大大提高了系统的运行效率。

Method of generation and rapid showing for 3D rough models

In order to solve the problems that seriously affect optical effects of simplified complex 3D models generated by traditional methods, such as cracks, texture stretches, flaws, dislocations and so on, which exist on surfaces of the models, this paper proposes a method of generation and rapid showing for 3D Rough Models, using Billboards as carriers of models, implementing the function of rotating Billboards followed by viewpoint with the usage of GPU technology, replacing with available texture image dynamically from the angle between viewpoint and Billboard. Experiments show that at a distance, Billboards generated by this method are almost the same with original models and can absolutely replace them, at close range, Billboards have inappreciable geometric distortion .Therefore, the method is suitable for coarse-level LOD, especially for Digital City and Digital Earth system with magnanimity data, which not only guarantees the optical effects of original models, but also greatly enhances the efficiency of the system.