【作者】 宋涛； 欧宗瑛； 刘斌；

【Author】 SONG Tao, OU Zong-ying, LIU Bin (Key Laboratory for Dalian University of Technology Precision & Non-tradidonal Machining of Ministry of Education, Dalian 116024, China)

【机构】 大连理工大学精密与特种加工教育部重点实验室；

【摘要】 超大体数据的可视化为医学研究人员深入研究人体内部的详尽信息提供了有效途径。本文提出了一种新的基于并行投影Shear-Warp分解的射线模板快速RayCasting体绘制算法。体数据采用有效的八叉树存储和表达方案。八叉树的适应性均一化分级策略使得算法简化了不必要的处理过程的同时为构建用于RayCasting算法的射线模板和后续的交叉计算提供了有利的应用基础。针对体绘制中八叉树编码体数据构造基本的交叉运算如节点单元定位、区域定位和邻接节点单元搜索的需要,本文也相应的提出了简单而且有效的方法。这些方法是非递归的、减少了比较运算的同时不需要构建中间结果列表,进而减少了对内存的占用和避免了繁重的交叉计算。所提出的体绘制算法能在标准PC平台下快速实现超大型数据集的处理和高质量的人体内部结构图像的绘制。更多还原

【Abstract】 Visualization of large volumetric data sets, which can be obtained from numerical simulations or sensing instruments, provides medical scientists with gaining insights into the details of the human body interior. This paper proposes a new template-based raycasting scheme using shear-warp factorization for expediting parallel viewing of volumetric datasets. The volume coding scheme based on an efficient octree data structure is presented and the octree blocks are adaptively chosen to minimize unnecessary access process. The algorithm exploits the uniform shape, orientation and size of the "nonempty" octree blocks by building templates for ray/block intersections in the case of raycasting. The volume stored in octrees requires basic tree traversal operations such as point location, region location, and neighbor searches. This paper presents simple and efficient methods for performing searching and locating operations that are inherently non-recursive and reduce the number of comparisons with poor predictive behavior. The methods are table-free, thereby reducing memory accesses and avoiding the costly intersection computation. The high quality human body interior images of a large dataset can be generated by the proposed approach on a conventional PC platform fast.更多还原