COLOR COMPOSITION IN FREQUENCY DOMAIN VOLUME RENDERING
修订日期：1996-03-04
DOI：

 作者 单位 邓俊辉 清华大学计算机科学与技术系,北京,100084 唐泽圣 清华大学计算机科学与技术系,北京,100084

和传统体绘制算法相比，频域体绘制算法具有较低的算法复杂度，能够更快地完成对三维数据场的显示．然而这种方法却不能简捷有效地表示和处理数据场的深度信息，因此其生成的图象缺少深度的遮挡效果．有鉴于此，Ｌｅｖｏｙ等曾通过诸如线性深度补偿的技术来弥补这一缺憾．尽管如此，运用这种技术得到的结果和传统空域方法仍有明显的差别．本文首先着眼于对空域体绘制方法中广泛采用的离散颜色合成技术的分析，然后引出了透明度密度分布函数的概念，进而推导出连续形式颜色合成过程的解析描述．根据这个结果，只要对三维数据场的透明度分布加以适当限制，就能够通过频域体绘制方法来实现颜色合成，增加绘制的深度效果．作者最后指出，基本频域体绘制方法和Ｌｅｖｏｙ的线性深度补偿方法的实质可以看成是这种颜色合成过程的近似．文中对透明度均匀分布的情况做了详细讨论，并且给出了具体算法，同时用生成的图象实例相应地进行了比较．

The FVR(frequency domain volume rendering) approach explores a 3D data set faster than traditional spatial domain methods because of its innate lower computation al complexity. Unfortunately, images produced by the FVR methods always lack occlusion or depth cue since it is hard to represent and utilize the depth information within frequency domain efficiently. Some researchers have sought to make a remedy of this by means such as of linear depth cuing. This approach, however, is still far different from the conventional spatial domain methods which, using the color composition technique, generate images with realistic depth effect. In this paper, the discrete color composition of spatial domain algorithms is reviewed, before an analytical result of the continuous color composition is deducted. These equations become feasible for calculating in frequency domain on certain assumptions such as the transparency inside the data set is distributed homogeneously. The authors continue to discuss the detail implementation of this new algorithm based on their previous work, the substance classification FVR approach. The experimental result shows that both the computational complexity and the run-time cost are kept at the same level of former FVR algorithms.
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