通过子区域投影方法直接绘制三维数据场

A COHERENT SUBVOLUME PROJECTION APPROACH FOR VOLUME RENDERING

直接的体绘制技术提供了在一幅图形内显示三维数据场各种信息的巨大潜力，然而，上成这样的图形是极其昂贵的，而且高质量图形的绘制远远达不到交互实现的水平．与光线投射方法每次独立地处理一条光线相比，体绘制的体元投影方法按一定的顺序逐一处理数据场内每。个体元．图形绘制的复杂性是Ｏ（ｎ）（ｎ是数据场体元个数，即三个方向长度的乘积）．体元投影方法引起人门极大的兴趣是因为在处理过程中充分地利用了体元的空间连贯性．本文提出一个更有效的体绘制方法：体创分方法（ＶｏｌｕｍｅＰａｒｔｉｔｉｏｎｉｎｇ），不同于传统的方法，新的算法不仅利用了体元的空间连贯性而且还充分地利用了数据场函数值分布的空间连贯性，将数据场重新分割为有限个区域，使得在每一区域内数据值的变化较小，这些新产生的区域在体绘制过程中将作为新的体元来对待．针对分割后的数据场，文章详细介绍了通过区域边界投影的方式来计算区域对最后图形的贡献，理论分析与实验结果表明新的算法极大地改进了图形的质量，同时缩短了绘制时间，通常比传统的绘制方法快３至４倍．

This paper proposed a new volume rendering approach:Volume Partioning. It not only exploits the spatial coherence of cells but employs fully the spatial coherence of function distribution to partition a volume into a number of subvolumes,so that the function varies slowly over each subvolume. Each newly-generated subvolume can be considered as containing a single material and treated as the small-est unit instead of cells in the processing. Based on the subdivision of the volume, this paper discusses the calculation of intensity contributed by the subvolumes in detail. Theoretical analysis and a variety of experimental results show that the new approach improves image quality and reduces rendering time (Usually the new algorithm is three to four times faster than the traditional volume rendering algorithms.)