NAME
equaldx - Trace spacing regularization through interpola-
tion
SYNOPSIS
level [ -Nntap ] [ -Ootap ] [ -rsirs ] [ -reire ] [ -nsins ]
[ -neine ] [ -sis ] [ -eie ] [ -x0x0 ] [ -dxdeltax ] [
-xmaxmaxx ] [ -ntrntrout ] [ -hwiwrd ] [ -linear ] [ -mirror
] [ -dead ] [ -inimr ] [ -outomr ] [ -V ] [ -? -h -help ]
DESCRIPTION
equaldx regularizes trace spacing on a record by record
basis using linear or cubic interpolation and trace dis-
tances defined in the trace header. The only trace indexing
carried into the output data is the new trace distance and
any header entries required by the user and flagged on the
command line using the -hw entry below. Input data traces
need not be in any paticular order within a record. Output
data is ordered in increasing trace distance within each
record.
Currently the header information is interpolated using the
same algorithm as the data [linear or cubic spline]. Extra-
polation outside the range of the input data is handled by
either extending the closest trace [the default] or option-
ally mirroring the data across zero or -xmax. The -mirror
option is not recommended for split-spread data as it was
not designed for such usage. It was built for single sign
[positive or negative] data only.
equaldx gets data and parameters from command line argu-
ments. These arguments specify the input and output trace
data, the record and trace range to be processed, the time
window over which interpolation is to take place, the new
near offset, far offset and trace distance interval, the
number of traces desired each output record, the header
entries to be interpolated, the interpolation type, the
number of inside and/or outside traces to be mirrored and a
verbose printout flag.
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).
-rs irs
first record to process. (default = 1)
-re ire
last record to process. (default = all)
-ns ns
first trace in record to process. (default = 1)
-ne ne
last trace in record to process. (default = all)
-s s start time for interpolation in the units of your data.
Data prior to this time will not be interpolated. All
data will be passed. (default = 0)
-e e end time for processing in the units of your data.
Data after this time will not be interpolated. All
data will be passed. (default = all)
-x0 x0
trace distance for the first trace of each output
record. Progressively, each trace in the output record
will increase by deltax. This entry may be negative or
positive regardless of the sign of the trace distance
entry in your input dataset. The default is 0.0
-dx deltax
distance between adjacent traces within each output
record. Again there is no default.
-xmax maxx
trace distance for the last trace of each output
record. Progressively, each trace in the output record
will increase by deltax. This entry may be negative or
positive regardless of the sign of the trace distance
entry in your input dataset. There is no default.
-ntr ntrco
number of output traces per record. One of -xmax or
-ntr is required, if both are present -ntr takes pre-
cidence.
-hwhdrwrd
enter as many -hw entries as required. Each header
entry [mnemonic] flagged will be interpolated form the
input data and installed in the output header. The
only header entries that will be provided automatically
are DstSgn and TrcNum. You must flag any other entries
that you desire. The interpolation scheme used will be
the same used to interpolate the data.
-linear
Enter the command line argument '-linear to user linear
interpolation. The default is cubic spline interpola-
tion.
-mirror
Enter the command line argument '-mirror to mirror the
ends of the record prior to interpolation. The near
offset will be mirrored about zero and the far offset
will be mirrored about -xmax. The number of traces to
mirror in each case will be taken from the -in and -out
entries below. The default is to extrapolate by
repeating the nearest offset trace.
-dead
Enter the command line argument '-dead' to cause the
program to interpolate only dead traces. The routine
will get the trace distances for all traces, including
the dead ones, from the data so they had better be
there. If not interpolation to zero could be a prob-
lem. In this mode none of the command line entries for
trace spacing etc. are required or used.
-in imr
enter the number of traces to mirror on the near offset
side of the record. This is the number of live traces
to mirror across zero.
-out omr
enter the number of traces to mirror on the far offset
side of the record. This is the number of live traces
to mirror across -xmax [see above].
-V Enter the command line argument '-V' to get additional
printout.
-? -h -help
Enter -? -h or -help to get online help. The program
will terminate after printing a list of parameters.
BUGS
- unknown
SEE ALSO
gentrp spacetrp
AUTHOR
P.G.A. Garossino
[ATTC, socon 422-3932, pgarossino@amoco.com]
January 1997
COPYRIGHT
copyright 2001, Amoco Production Company
All Rights Reserved
an affiliate of BP America Inc.
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