中文摘要：

起伏地表条件下的高效高精度射线追踪方法是三维层析速度建模的关键技术。首先将多模板快速推进算法（MSFM）扩展到三维起伏地表条件下的走时计算。该方法通过变换坐标系引入6个三维差分模板,综合考虑坐标轴方向和对角线方向的信息,在较少增加计算成本的同时显著提高了计算精度。在MSFM的基础上,采用三线性插值和Runge-Kutta方程求取走时梯度,并从接收点开始向激发点沿走时梯度反向追踪得到射线路径。三维均匀模型和复杂近地表模型的测试应用表明,基于三维多模板快速推进算法的射线追踪方法要优于基于传统快速推进算法（FMM）的射线追踪方法。

英文摘要：

High-efficiency and accurate ray tracing method for irregular topography has been the key technique in 3Dtomography velocity modeling.The multi-stencils fast marching method（MSFM）is developed into 3Dtraveltime computation for irregular topography.Introducing six 3Ddifferential stencils by coordinate rotation,grid points along both coordinate axes and diagonal directions are covered.Thus,the computational accuracy is remarkably improved without much extra computation cost.On the basis of the traveltime field calculated by MSFM,traveltime gradient could be calculated by using the tri-linear interpolation and the Runge-Kutta equation and the ray path can be obtained by backward tracing from the receiver to the source along the traveltime gradient direction.Theoretical tests on a homogeneous model and a complex near-surface model proved the advantages of this method compared with the raytracing based on conventional fast marching method（FMM）.