中文摘要：

直接体绘制需要借助于传输函数,而设计一个有效的传输函数非常耗时且需要具备丰富的经验.为此提出一种不透明度自动调节的可视化方法.通过分析采样光线提取出数据的特征,并将这些特征抽象为不同层次的采样点,抽象采样点的不透明度根据采样光线上特征数的变化而改变;在保证最远抽象采样点可见度最大的前提下,推导并修改传统体绘制积分方程,得到基于抽象采样点的体绘制积分方程.实验结果表明,该方法不依赖于传输函数,能有效地展示体数据中的特征信息.

英文摘要：

Direct volume rendering （DVR） is an effective method for volumetric data visualization,while it usually needs a transfer function that assigns different optical properties such as color and opacity to the voxels.However,to find a good transfer function is time consuming,since it generally requires the considerable expertise of the user.In this paper,we present feature-based opacity modulation for DVR.We obtain the feature of voxels from the ray profile of DVR,and these features are represented as different layers of sampling points.The opacity of these sampling points will be associated with the number of features of the ray.In order to achieve maximum visibility of the farthest sampling points,we modify the traditional ray integral for DVR.Our demonstration shows that our approach does not require the complicated transfer function,and it can produce more features in the final rendered image than previous methods.