| 1. | But the standard mc has some shortcomings : firstly , the standard mc picks up isosurfaces by threshold , however , threshold segmentation is invalid for picking up tissues or organs from some medical images ; secondly , the standard mc pocesses cubes one by one , that is to say , all the cubes will be checked , and the algorithm spents 30 % - 70 % of time to check the null units , so we need a reasonable data structure to travel the space data and accelerate the checking or filting of null units ; thirdly , the standard mc has a large scale of triangles , normally , the tissue or organ reconstructed includes hundreds of thousands so much as millions of triangles , this means it hardly to execute real - time rendering or interaction ; lastly , the standard mc can not get the very smoothly surface mesh , and there will be some unexpected accidented cases , especially in the case of big errors in oringinal data
但是标准mc算法存在较大的问题:标准mc算法实质上是通过阈值分割来提取等值面,阈值分割对某些医学图像的组织或器官的提取难以得到较好的效果;标准mc算法是逐个移动立方体来进行处理,就是说对所有的立方体都要进行一次检测,算法执行中30 % ~ 70 %的时间用在对空单元的检测上,因此需要有一种合理的数据结构对空间数据进行有效的遍历,以加速对空单元的检测和过滤;标准mc算法产生了大量的三角面片,一般重建的组织或器官包含数十万甚至上百万的三角面片,难以实现实时的绘制和交互操作;标准mc算法得到的表面网格并不光滑,会有一些不期望的凹凸,特别是在原始数据有较大误差的情况下尤其突出。 |
