operator is discretized at spaced apart sample points along the dmo aperture segment the spacing being equal to or less than the output grid dimensions a exponentially tapered sinc filter function is applied to the samples which are then interpolated onto the output grid application_number US 83263297 A description the evils of spatial aliasing using conventional data processing methods were demonstrated earlier with respect to fig1 3 an improved economical method for de aliasing a 3 d kirchhoff dmo operator will now be explained please refer to fig4 which illustrates a portion of an area of interest as before the grid lines intersect at stacked output locations as is well known in the normal course of seismic survey operations each output point is in effect a bin having dimensions dx and dy as shown in fig1 each bin contains data from the many different source receiver trajectories that will become the members of a stack a source receiver dmo aperture segment 10 extends along an arbitrarily chosen azimuth bounded by s 1 source and r 1 receiver a second dmo aperture segment 12 extends along a line bounded by a source s 2 and receiver r 2 aperture segments 10 and 12 is sampled discretely with symmetrically distributed spaced apart sample points as shown by black circles such as 16 18 20 and 30 the distance d u03b4x 2 u03b4y 2 1 2 between any two adjacent spaced apart sample points such as 16 and 18 is such that d projected onto the grid x axis is less than or equal to dx and d projected onto the y axis is less than or equal to.