** Next:** Gulf of Mexico stack
** Up:** COMMON-MIDPOINT STACKING
** Previous:** Crossing traveltime curves

The difference between **stack**ing as defined by
`nmo0()` and by
`nmo1()`
is in the weighting function .This weight made a big difference in the resolution of the stacks
but I cannot explain
whether this weighting function is the best possible one,
or what systematic procedure
leads to the best weighting function in general.
To understand this better,
notice that can be factored into two weights, and *t*^{-3/2}.
One weight could be applied before NMO and the other after.
That would also be more efficient than weighting inside NMO,
as does `nmo1()`.
Additionally, it is likely that
these weighting functions should take into account
data truncation at the cable's end.
Stacking is the most important operator in seismology.
Perhaps some objective measure of quality can be defined
and arbitrary powers of *t*, *x*, and can be adjusted until the optimum stack is defined.
Likewise, we should consider weighting functions in the spectral domain.
As the weights and *t*^{-3/2}
tend to cancel one another,
perhaps we should filter with opposing filters
before and after **NMO** and stack.

** Next:** Gulf of Mexico stack
** Up:** COMMON-MIDPOINT STACKING
** Previous:** Crossing traveltime curves
Stanford Exploration Project

12/26/2000