Abstract: volume rendering methods have been the active research area since it’s the ability of visualizing the inner structure of 3D volume data. However, the trade-off between the rendering speed and acquiring high-quality rendered images because of the increasing of sampling rate restricts the further development of direct volume rendering methods. The paper introduces the pre-integrated classification technique on the basis of expatiating the classification and volume rendering integration. The pre-integrated classification has the potential to improve the accuracy and the performance of the volume renderer at the same time. In the end, some examples and advices for pre-integrated classification technique are given.

Key words: classification, volume rendering integral, pre-integrated classification, direct volume rendering

摘要： 随着三维数据场可视化精度要求的不断提高，直接体绘制方法已经成为该领域的研究热点。然而，提高数据场采样率以获得高质量的图像与绘制速度的降低这一矛盾，很大程度上限制了体绘制方法的研究进展。本文阐述了体绘制方法的关键技术——分类和体绘制积分，并在此基础上介绍了预积分分类技术。该方法能够同时提高体绘制方法的执行效率与图像质量，并给出了实例说明。最后，提出了预积分分类技术中存在的一些问题。

关键词: 分类, 体绘制积分, 预积分分类, 直接体绘制