NAME
fkterp - f-k domain interpolation beyond aliasing
SYNOPSIS
fkterp [ -Nntap ] [ -Ootap ] [ -wn1w ] [ -ln2w ] [ -wpadn1p
] [ -lpadn2p ] [ -velvel ] [ -NMO ] [ -V ] [ -? ]
DESCRIPTION
fkterp reads each input seismic record and performs the f-k
domain beyond aliasing computation of Gulunay and Chambers
to interpolate a trace between each existing trace. the out-
put record will contain 2 * ntrc - 1 traces, where ntrc is
the input number of traces per record. Since stationarity
is a major assumption of the method the computations are
done in a small two dimensional window which moves over the
input record. The results of the calculations for each win-
dow position are then blended together to form the output
matrix. This is basically a USP version of the DDS fkinterp
The refernces are:
Gulunay, N and Chambers, R, 1997, Generalized f-k domain
trace interpolation: 67th Annual Int. Mtg., Soc Expl Geo-
phys, Expanded Abstracts, 1100-1103
and
Gulunay, N and Chambers, R, 1996, Unaliased f-k domain trace
interpolation (UFKI): 66th Annual Int. Mtg., Soc Expl Geo-
phys, Expanded Abstracts,1461-1464
fkterp gets data and parameters from command line arguments.
These arguments specify the input and output trace data.
Command line arguments
-Nntap
Enter input data set name or file immediately after
typing -N; entering nothing specifies a stdin pipe.
This file should include the complete path name if the
file resides in a different directory. Example
-N/b/vsp/dummy tells the program to look for file
'dummy' in subdirectory 'vsp' stored in directory b.
-Ootap
Enter output data set name or file immediately after
typing -O. This output file is not required when pip-
ing the output to another process. The output data set
also requires the full path name (see above).
-w n1w
Enter the temporal length in samples of the computa-
tional window. This is the small window of dimension w
x l (see spatial dimension below) within which the
interpolation is calculated and within which stationar-
ity is assumed. The window is moved over the entire
input record to generate the interpolated output
record. Generally the larger this window the faster
the run times; however the risk is that stationarity is
violated and the beyond aliasing calculations break
down. Default value of 12 is low and probably you
should not go lower than this.
-l n2w
Enter the spatial length in samples of the computa-
tional window. This is the small window of dimension w
x l (see temporal dimension above) within which the
interpolation is calculated and within which stationar-
ity is assumed. The window is moved over the entire
input record to generate the interpolated output
record. Generally the larger this window the faster
the run times; however the risk is that stationarity is
violated and the beyond aliasing calculations break
down. Default value of 6 is low and probably you should
not go lower than this.
-n1p n1p
Enter the number of samples to pad the temporal dimen-
sion of the comput ational window. Default is half the
temporal dimension.
-n2p n2p
Enter the number of samples to pad the spatial dimen-
sion of the computa tional window. Default is half the
spatial dimension.
-vel vel
Enter the value of velocity to be used in the optional
internal constant velocity NMO correction. To minimize
the aliasing affects of moveout, especially the really
low velocity events, this option can be used to apply a
quick, clean NMO correction prior to the interpolation.
This is then removed just before output of the interpo-
lated record. If more sophisticated NMO is required
(either a single v-t function or a velocity field) then
use bdnmo of anmo to externally NMO correct the data
before entering fkterp (don't forget to reverse NMO
correct after fkterp). Note: see bug report on man page
for explanation of IEEE messages when using this option
on SUN machines.
-NMO To minimize the aliasing affects of moveout this option
can be used to apply a quick, clean NMO correction
prior to the interpolation. This is then removed just
before output of the interpolated record. If more
sophisticated NMO is required (either a single v-t
function or a velocity field) then use bdnmo of anmo to
externally NMO correct the data before entering fkterp
(don't forget to reverse NMO correct after fkterp)
-V Enter the command line argument '-V' to get additional
printout.
-? Enter this (or '-?' if you are running in c-shell) to
get online help. The program will terminate after
printing a list of parameters.
BUGS
- unknown
Note that on the SUN machines one can get IEEE messages if
either inputting NMO corrected data or using the internal
constant velocity NMO correction. EVERYTHING IS REALLY OK.
What happens is that after NMO there is a wedge of zeros
generated at the bottom of the record and when the computa-
tional window hits this just right the SUNs cough up these
messages. Windowing the NMO'd data prior to fkterp will make
the problem go away but regardless the output will be fine.
SEE ALSO
spacetrp gridr equaldx radonr
AUTHOR
Port of code from John Etgen by Paul Gutowski
(pgutowski@amoco.com)
COPYRIGHT
copyright 2001, Amoco Production Company
All Rights Reserved
an affiliate of BP America Inc.
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