A 3-D Ray Tracing Algorithm Using Traveltime Gradient and Its Application

The limitation of grid discretization introduced in traditional 3-D ray tracing algorithm always leads to some irregularity, roughness and low precision in the calculation of ray paths. To solve the problem, according to the principle that first arrival ray path is perpendicular to the wave front, a new ray tracing method using traveltime gradient is proposed in this paper. The scheme is that minimum traveltime ray path between receiver and source point will be calculated by tracking along the opposite direction of traveltime gradient, which is computed on a continuous field of traveltime constructed by cubic B-spline interpolation. The disadvantage of discreteness in the grid partition is eliminated due to the continuity of the interpolated gradient. The experimental results show that the algorithm can not only get smoother ray paths but also increase the accuracy and efficiency comparing with the traditional 3-D ray tracing method.