三维直接体显示算法是显示三维数据体的一种重要显示方法，已广泛应用在医学图象生成和科学可视化领域之中。光线投射法又是三维直接体显示算法中最基本的一种方法。然而由于光线投射法需要大量的计算而受到限制。该文从减少光线投射数目的角度出发，提出了一种基于最优采样模式的频率投射算法。它的优点是不仅可以利用人的简单的视觉模型和强大的傅立叶分析工具，而且在采样模式上也更能符合人类视觉特点，减少了假模式，从而使更多

Direct Volume Rendering (DVR) algorithm is an important method to display the three dimensional data and it is widly used in medical image rendering and sicentific visualization. Furthermore, ray casting method is a basic method of DVR algorithm. However, it is limited by plenty of computation. From the view of reducing the number of casted ray, this article provided an adaptive ray casting method based on the optional sampling pattern. The advantage of the algorithm is not only using the simple human vision model and powerful fourier analysis tools, but also making the advantage of the sampling pattern being more suitable to the human vision model and reducing the aliase pattern. As a result, more noise is changed to be more insensitive. So, this algorithm not only improves the image rendering quality, but also reduces the image rendering time.