NAME
pstack - module to do stacking of input records with selec-
tive header value processing for the output stacked trace.
Stacking using phase vector summation is available. Gathers
are stacked into a single trace in memory making the stack-
ing of very large gathers possible.
SYNOPSIS
pstack [ -Nntap ] [ -Ootap ] [ -Fftap ] [ -sist ] [ -eiend ]
[ -nsnstr ] [ -nenetr ] [ -rsnrst ] [ -renred ] [ -exppwr ]
[ -phase ] [ -V ] [ -? ]
DESCRIPTION
pstack creates one stacked trace per input record. The
stacked samples are normalized by the number of live [non-
zero] samples included in the stacked output. An optional
fold trace is available documenting the sample-wise fold of
the output stack. If a -exp is supplied on the command line
the normalization denomenator, usually the number of live
samples at a given time, will be raised to the given
exponent. This routine is preferable to program stak when
operating on a dataset containing very large numbers of
traces per record. No attempt is made to hold the whole
record in memory [therefore no median options]. Instead a
sumation trace and number of live sample trace is accumu-
lated for each record. The summation trace is divided
sample-wise by the number of live sample trace prior to out-
put. The output trace header will contain the depth index
in DphInd, the line index in LinInd, the source point over
cdp in SrcPnt, the near offset on mute start time in
VPick1, the near offset off mute start time in VPick2, the
near offset arcsdatum value TVPT21, the near offset in
DstSgn, the cdp bin center X and Y co-ordinates in CDPBCX
and CDPBCY the group elevation in GrpElv and a dead trace
flag in StaCor . All other trace header entries are car-
ried from the first trace of the record being stacked.
If run using the -phase option then the input is assumed
to be phase measured in degrees [between 0.0 and +/- 180.0].
Rather than stacking the samples across the record with nor-
malization for the number of live samples a vector summation
is undertaken to determine the resultant phase angle after
summation of all samples at a given time within the record.
Each input sample is assumed to be a vector of unit length
pointing in the direction of the phase value of the sample.
The vector is converted to it's rectangular components and a
running sum of these is maintained for all traces of the
input record. Once complete the resultant vector is again
expressed in polar co-ordinates and the angle written to the
output trace. In this mode all dead traces are ignored
since 0.0 degrees is a valid phase angle.
pstack gets both its data and its parameters from command
line arguments. These arguments specify the input, output,
the design window, the start and end traces, the start and
end records, the denominator exponent, the phase flag and
verbose printout, if desired.
Command line arguments
-N ntap
Enter the input data set name or file immediately after
typing -N unless the input is from a pipe in which case
the -N entry must be omitted. This input 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 directory '/b/vsp'.
-O otap
Enter the output data set name or file immediately
after typing -O. This output file is not required when
piping the output to another process. The output data
set also requires the full path name (see above).
-F ftap
Enter the output Fold data set name or file immediately
after typing -F. The default is to NOT output this
dataset.
-s ist
Enter the start time of the design window. The default
is the beginning of the trace. The filter will be
applied to the whole trace, regardless of the -s and -e
entries.
-e iend
Enter the end time of the design window. The default
is the end of the trace.
-ns nstr
Enter the start trace number. The default is the first
trace of the record.
-ne netr
Enter the end trace number. The default is the last
trace of the record.
-rs nrst
Enter start record number. Default value is the first
record.
-re nred
Enter end record number. Default value is last record.
-exp pwr
Enter an exponent used to power the denomenator for
stack normalization. Default is to normalize by number
of live samples only. It this parameter is entered the
number of live samples in the denomenator will be
raised to this power before normalization.
-phase
Enter the command line argument '-phase' to perform a
vector summation of the input phase data. It is
assumed that the input phase values are between 0.0 and
+/- 180.0 degrees. A conversion to radians is done
within the code so that if you input phase in radians
you will not get the correct summation. In this option
0.0 degrees is assumed to be in the positive x direc-
tion, 90.0 is toward the positive y direction [picture
positive x to the right and positive y up].
-V Enter the command line argument '-V' to get additional
printout.
-? Enter the command line argument '-?' or -h or -help
to get online help. The program terminates after the
help screen is printed.
BUGS
Unknown
SEE ALSO
stack(1) rost(1) rstak(1) stack3d(1) vstak(1) mvstak(1)
AUTHOR
P.G.A. Garossino [APR:x3932:1993] requested by Todd Jones
[Eur/USA]
COPYRIGHT
copyright 2001, Amoco Production Company
All Rights Reserved
an affiliate of BP America Inc.
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