最短路径射线追踪方法及其改进

综述了用网络最短路径算法求解地震射线追踪问题的原理、方法技术以及存在问题和改进措施。特别介绍了作者在最短路径算法基础上，提出的动态网络最短路径地震射线追踪方法。该方法先采集从炮点到整个模型所有节点上的初至旅行时，其中，在一个单元内，对相邻每对已计算出最小旅行时的节点进行线性插值，并利用Fermat原理计算未知节点的最小旅行时；然后，利用同样的方法，从接收点开始，反向追踪炮点到接收点的射线路径、该方法能适于各种复杂的非均匀介质，极大地提高了射线追踪的精度。

Improvement of shortest path ray tracing method

The principle and method of seismic raytracing with shortest path algorithm in networks are discussed, the relevant drawbacks in which and improved measures are also analyzed. Especially, we develop a shortest path raytracing method with dynamic networks based on the shortest path algorithm. The wavefront times are sampled at the nodes away from the source throughout the entire model. The first arrival times at nodes in a cell are expressed with linear interpolation between traveltimes obtained aforehand at each pair of two neighboring nodes, and then determined by Fermat principle. After the first arrival times being sampled throughout the model, the raypaths from the source to each receiver are obtained backward away from the receiver to source in the same way as the forward sampling. This algorithm is regardless of model complexity, and has a higher precision for computation of seismic traveltimes and raypaths.