A Global Minimum Traveltime Ray Tracing Algorithm of Wavefront Expanding with Interface Points as Secondary Sources

Abstract

AbstractThe shortest path ray tracing presented by Moser is a kind of fast and stable method to calculate global minimum traveltimes and raypaths. But it has two drawbacks. One is that most derived zig‐zag raypaths are longer than true paths and thus mispositioned. The other is that there may be several equally short paths, especially in flat areas with low velocity variations. The wavefront expanding method with interface points as secondary sources studied in the paper aims to solve the problems. Different from Moser's method, the method only set secondary sources on interfaces between different media. Straight rays from a secondary source can reach any node as long as they don't penetrate interfaces. So waves propagate along accurate paths in homogeneous layers or blocks. Obviously, there are much more ray directions from a secondary source in the method than in Moser's method. The main tracing errors of the method only come from interface discretization. As a result, ray tracing with the method can get much more accurate results than Moser's method. At the same time, the method is efficient as there are much less secondary sources than those in Moser's. Numerical examples show that the method is effective.