基于有序体数据的体绘制方法(英文)

Volume Rendering Based on Sorted Volumetric Data

目的体绘制是三维可视化的有效方法 ,但是它处理的数据量巨大。本文提出一种称为有序体数据的空间数据结构 ,它可以有效地加速体绘制而对图像质量没有影响。方法在体绘制前 ,将每个体数据的每个层片编码成以体素值为序的有序数组。依据不透明度函数可确定出不透明体素所对应的体素值范围。通过对有序数组的截取 ,可快速地定位不透明体素 ,而跳过所有透明的体素。该算法的优点是在不透明度函数改变后无需重新生成有序体数据 ,方便体绘制中的交互 ,快速地绘制出结果图片。结果在典型的PC机上验证了上述算法 ,对于CT头部体数据 ,绘制时间不大于 1s,绘制速度达到了临床诊断的要求。结论基于有序体数据的体绘制方法思路简洁 ,易于实现 ,不受透明度变换函数的约束 ,显著提高了绘制速度 。

Objective To describe a spatial data structure called sorted volumetric data structure which speeds up the volume rendering and will not affect image quality. Method Before volume rendering we transfer each slice of volume into an array indexed by the value of voxels, element in which stores the position of each voxel. According to the opacity transfer function, we can affirm the value ranges of voxels that are non transparent. Therefore we translate, resample and composite only the voxels in the value ranges. By marching through the sorted arrays, we locate the non transparent voxels rapidly and skip all voxels that are transparent. The sorted data structures need not recompute whenever the opacity transfer function changes and are not restricted on the opacity transfer function. Result The method presented in this paper has been implemented in a standard personal computer. The rendering time for CT head volume data is less than 1 s that is satisfied with the diagnostic purpose. Conclusion The concept of proposed algorithm is simple, easy to realize and it is not recomputed whenever the opacity transfer function changes. By using the sorted volumetric data structure, we speed up the volume rendering without affecting image quality.