Finite Difference Migration
Finite difference migration was done in MIGTX module. Main parameter is TAU. But when there are too few points in NFP, the filter points, the result shows undermigration. In ideal case, many NFP will enhance the result but in practical point of view, it will increase the computational cost of the process. TAU specifies the step increment of the time layer. According to TAU, the module interpolates the velocity. So each time layer would have a different velocity value. In a fixed TAU value of 20 ms, the result follows the same trend as Kirchhoff migration. Slow velocity (1500 m/s) results in undermigration (Fig. \ref{682102}), correct velocity (2250 m/s) shows smeared point scatterer (Fig. \ref{284318}) and high velocity (3000 m/s) shows overmigration (Fig. \ref{311825}).