The goal of dip estimation is to find a local stepout,
, that destroys the local plane wave such that,

(9)

where u is the wavefield at time and offset h.
For all gathers, we evaluate the slope with
a method based on high-order plane-wave destructor filters
Fomel (2002). With the Z transform notation,
Fomel (2002) shows that there is a 2-D filter

that annihilates the local plane wave. The number of
coefficients for the filter B_{n} is n. The filter coefficients
are functions of
as detailed in equations (9) and (10) of
Fomel (2002).
For instance, if n=3, we have

(12)

In equation (11), is unknown and is estimated
with a non-linear solver.