In connection with the problem of the travel time accuracy (LTI), an improved ray tracing method based on then linear travel time interpolation but using nonlinear interpolation is developed in this paper. The method takes advantage of multiple nodes on the boundary for reducing interpolation error, thus, the travel time accuracy is increased in full fi eld while the advantages of LTI method in rapid calculation and overall optimization are retained. The comparison of numerical and experimental results shows that the nonlinear interpolation algorithm is higher accuracy than the LTI algorithm and it can be used to trace several kinds of ray paths such as direct wave, refracted wave and transmitted wave for complex media.%针对走时线性插值法(LTI)的计算精度问题，利用非线性插值替代传统的线性插值。该方法利用边界上多个节点的走时，使得插值误差减小，从而提高整体边界网格离散点走时精度，同时保留LT I所具有快速、全局性的优点。数值模拟结果表明，非线性插值算法比LT I算法精度高，可以追踪包括直达波、折射波、透射波等多种射线路径，适合速度突变模型。
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