中文摘要：

针对标准光线投射算法计算量大、速度慢的特点，本文提出一种满足医学图像实时需要的体绘制加速新算法。利用图元在矩阵变换前后呈均匀变化的特性，递推得到除6个顶点外的其余重采样点的物体空间坐标，大大减少矩阵运算量；同时利用包围盒技术避免对空体元的采样，通过将Bresenham算法扩展至三维使投射光线的体元化与重采样参数的计算一次完成，极大地加速光线投影的效率。大量的对比实验均表明，本丈算法和传统标准算法具有相同图像质量，体绘制的速度提高了2-3倍。

英文摘要：

Aiming at the tremendous computation and the low rate of standard ray casting algorithm, a new speed-up algorithm of ray casting volume rendering was presented to realize the real-time manipulation of medical images. Firstly, with the uniform changes characteristics of primitives before and after matrix transformation, all re-sampling points except for the six vertex were deduced so as to reduce matrix computation greatly. Secondly, the boundary box technique was utilized to avoid the sampling in empty voxel. Thirdly, extending the Bresenham algorithm to three-dimension, casting ray voxelizing and the re-sampling parameters were computed simultaneously, which greatly improved the efficiency of ray casting. All results of a mass of contrasting experiments show that the acceleration algorithm can produce the same quality images as the conventional standard algorithm ,but the velocity of volume rendering is increased by two or three times.