Abstract: Ray casting is an important algorithm in direct volume rendering，but it has the disadvantages of the large amount of computation and inefficient computation of sampling-points.In order to accelerate the speed of the algorithm，this paper presents a fast intersecting technique of a line with some family planes，so using the intersected points can easily gain the sampling points and their characters.In order to improve image quality，the paper also presents an adaptive sampling method based on rapid intersecting.The experiment shows that this algorithm can accelerate the speed of ray casting and doesn’t degrade the image quality.

Key words: direct volume rendering, ray casting, intersecting, adaptive, volume data

摘要： 光线投射算法是体绘制技术中的一种重要算法，但其自身存在采样效率低和绘制速度慢等问题。为了提高光线投射算法的绘制速度，本文提出了一种改进求交的自适应光线投射体绘制算法，算法采用一种快速求交方法和自适应采样来提高体绘制速度，试验结果表明该算法能在基本不影响图像质量的同时提高算法的速度。

关键词: 体绘制, 光线投射, 求交, 自适应, 体数据场