基于边界线性走时插值的射线追踪算法

Ray Tracing Algorithm Based on Boundary Linear Traveltime Interpolation

在传统的基于线性走时插值(LTI)的射线追踪算法中,由于线性假设,射线经过多个网格单元会导致误差累积.将其应用于工业探伤的超声计算机断层成像时,待检测材料往往是背景区域和少量缺陷区域组成的集合.为减小累积误差,文中提出了一种新的基于边界LTI的射线追踪算法.该算法通过在不同区域的边界上插入节点来确定射线的折射角度,以减小累积误差,同时借鉴多方向循环扫描的思想来解决逆射问题.模拟实验结果表明,文中算法的走时计算及射线路径追踪精度、运行时间均优于传统LTI算法和交叉扫描LTI算法.

In the traditional ray tracing algorithm on the basis of linear traveltime interpolation （LTI）, rays trans- mitting through multiple grids may cause error accumulation due to the linear assumption. When the algorithm is applied to the computerized tomography for industrial flaw detection, the materials to be detected often become a collection of the background and a small amount of defect areas. In order to reduce the accumulative error in this application, a new ray tracing algorithm on the basis of boundary LTI is proposed. In this algorithm, nodes are in- serted on the boundary of different areas to determine rays＇ refractional angle and to further reduce the accumulative error, and the multidirectional cyclic scanning is used for reference to guarantee the ray path when rays transmit in a reverse direction. Simulated results show that the proposed algorithm is superior to the traditional LTI algorithm and the cross-scanning LTI algorithm due to its high traveltime computing accuracy and ray path-tracing accuracy.