摘要： 为了提高光线跟踪速度，在深入研究和比较各种光线跟踪加速算法的基础上，提出了一种采用自动分组技术的改进3d-DDA 快速跟踪算法。该算法并不将整个空间进行剖分，而是采用自动分组，将包含实体数达到某一门槛值的组进行剖分，并结合包围盒进行判断。网格内保存所含实体链表，以跨越一格光线参数t 的变化量为增量前进。该算法在保证图像质量的同时绘制速度提高了一个数量级左右，为快速生成真实感图形提供了有效的手段。

关键词: 真实感图形；光线跟踪；自动分组；3d-DDA

Abstract: To improve the speed, accelerating algorithm for ray tracing is fully studied and compared and an improved 3d-DDA ray tracing algorithm based on auto-grouping is presented. It doesn’t divide the whole space, but auto-grouping the whole scenes, to divide the group that including enough num of entities. And to interact with ray combine with bounding volume, the entity link is saved by grid, the ray proceeding by the change of t.The accelerating algorithm not only improves the rendering speed more than ten times but also brings no depress on image quality. It gives a more capability method for the application of rendering 3-D graphics

Key words: 3-D graphics; Ray tracing; Auto-grouping; 3d-DDA