直接读入实测数据，以grd网格化格式，然后给定延拓高度，利用了快速傅里叶变换，快速得到延拓后的grd数据，直接用surfer画图即可。(Directly read the measured data, GRD grid format, and then given the height of the extension, the use of fast Fourier transform, quickly obtained after