# How do you define an aperture for seismic data processing?

Lets consider this in marine seismic processsing. I am assuming you know what a first order primary reflection is, if not, I can define it.

Ok, so if we were to have a source $(S)$ and receiver $(R)$ lying directly on the $x$ axis seperated with a distance of $n$ meters, and a horzontial reflective surface, then the reflection point for a first order multiple would lie at the mid point $S$ and $R$, i.e at the point $\frac{n}{2}$. However, if we were to have a dip of a certain angle in the $x$ direction, then now our reflection point would change. The "aperture" is a range in which the new reflection point could lie in.

As this is done in the deep water marine environment, we might not know the exact angle of the wave as it goes down and the exact angle of the dip of the reflector, so how would we come up with an aperture to cover the possible location of the surface reflection point? In this case, the aperture will just be a line.

Similarly, if there was a dip in the $y$ direction, how would we come up with an aperture that could help us cover the surface reflection point?