医学图像三维重建中的快速表面绘制  

Fast Surface Rendering for Three Dimensional Medical Image Reconstruction

作　　者：李飞鹏 廖孟扬[2] 徐振勤[2] 王思贤[2] 

机构地区：[1]武汉测绘科技大学测绘遥感信息工程国家重点实验室,武汉市珞喻路129号430079 [2]武汉大学图像及信息研究所,武汉市珞珈山430072

出　　处：《武汉测绘科技大学学报》2000年第2期153-157,共5页Geomatics and Information Science of Wuhan University

摘　　要：简述了医学图像三维可视化表面绘制的基本原理。由于三维体数据中的等值面直接对应着组织器官的表面 ,而自然器官的表面应处处连续 ,为进一步加快绘制速度 ,假定待提取等值面连续 ,对三维体数据先进行 8像素等间隔采样和阈值判断 ,分离出边界点 ,然后只对边界点邻域做阈值判断。与DividingCubes算法相比 ,优化后的算法计算量不到原来的 1 /4 ,绘制结果图像也比较逼真。Surface rendering, together with volume rendering, is the most popular sort of algorithm used in scientific visualization. Though developed later than surface rendering and having a wider adaptability to object data sets, the algorithm of volume rendering still can not be put into use in practical medical imaging application,simply because it could not meet the speed requirement for interactive operation due to the large amount of computation involved.Surface rendering thus becomes the general method for visualization in most medical imaging, for it is at least more computation_economic than its counterpart. The common algorithm of surface rendering can be generalized by two main steps — isosurface extracting and isosurface shading. Of all methods proposed for isosurface extracting, Marching Cubes (or Dividing Cubes) is the most widely used one. To pick up an isosurface for display, it traverses all the cells in the data set, and for each cell it compares the included eight vertexes to a certain threshold to decide whether it is a boundary cell or not. However, extensive investigation shows that, of all the units checked out, there are usually only less than 10% are useful. Considering the inefficiency in the search for boundary cells the whole run time can be further reduced by applying an optimized search order. Because each isosurface we are extracting from the volume data set actually corresponds to the epidermis of a human organ, we assume that the isosurfaces are continual as well. With the continuity assumption, the isosurface extracting can be accomplished by two steps. First, the volume data set are subsampled by 1/8 voxel.After comparing with the threshold, all the voxels in the subset are classified into boundary points and non_boundary points. After the search for isosurface is carried out, but only in the neighboring space of boundary points, those voxels labeled as non_boundary points will be completely neglected for further processing. As a result, the optimized algorithm is at least 4 times more

关 键 词：三维可神化 表面绘制 图像分割 等值面 医学图像 

分 类 号：P231.5[天文地球—摄影测量与遥感]