NAME
wind - window data
SYNOPSIS
wind [ -Nntap ] [ -Ootap ] [ -sist ] [ -eiend ] [ -nsnstr ]
[ -nenetr ] [ -rsnrst ] [ -renred ] [ -tiramp ] [ -vvel ] [
-hwhwd ] [ -I ] [ -P ] [ -Z ] [ -H ] [ -R ] [ -V ] [ -? ]
DESCRIPTION
wind
wind gets both its data and its parameters from command line
arguments. These arguments specify the input and output
data streams, start and end window times, start and end
traces, start and end records, start window adjustment velo-
city, trace header start time mnemonic, ramp length, pass
flag, zero flag, hyperbolic window start flag, ignore TmMsFS
flag and verbose printout if desired.
Command line arguments
-N ntap
Enter the input data set name or file immediately after
typing -N. This input put file should include the com-
plete 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 'vsp' stored on the
'b' disk.
-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).
-rs nrst
enter the start record to process. This parameter may
also be used in conjunction with -P below to apply a
window to only specific records while passing the whole
dataset. The default is the first record of the
dataset.
-re nred
enter the last record to process. This parameter may
also be used in conjunction with -P below to apply a
window to only specific records while passing the whole
dataset. The default is the last record of the
dataset.
-ns nstr
enter the start trace to output. This parameter may
also be used in conjunction with -P below to apply a
window to only specific traces within a record while
passing the whole dataset. The default is the first
trace of the record.
-ne netr
enter the end trace to output. This parameter may also
be used in conjunction with -P below to apply a win-
dow to only specific traces within a record while pass-
ing the whole dataset. The default is the last trace
of the record.
-s ist
enter the desired window start time in the units of
your dataset. The program will assign the start window
time to be [TmMsFS + ist]. Consider the case where a
dataset is windowed twice. The first operation uses a
start time of 100 ms. resulting in an output dataset
[data1] with a TmMsFS value set to 100 [or the time of
the closest sample to that value]. The second opera-
tion uses a start time of 150 milliseconds resulting in
the window positioned 50 milliseconds from the start of
the [data1]. If you want to start a window at 150 mil-
liseconds below the start of [data1] you would need to
either use a -s[] value of 250ms or use the -I flag
[see below] causing the routine to ignore the TmMsFS
entry in the input dataset. If no -s[] entry is sup-
plied the program will use as the window start the
lineheader entry TmMsFs from the input dataset. If
you find your window being mispositioned check the
TmMsFS entry in your dataset to verify that it is
correct.
Note: the start time may be negative in which case the out-
put trace is the input trace shifted down by a time equal to
the window start time.
-e iend
enter the desired window end time in the units of your
dataset. The default is the last sample of your
dataset.
Note: The end time may be longer than the input trace in
which case zeroes are appended to the input trace.
-t iramp
Enter the ramp length in the units of your dataset to
be applied to the top and bottom of the traces.
Default = 0ms. If a more severe ramp function is
desired several wind runs may be piped together with
the same ramp length, however one should remember that
the first wind only should do the actual windowing (if
the desired window is not equal to the original trace
length).
-hw hdrwrd
Enter the trace header mnemonic containing the start
time (in the same units as the dataset). The window
start time used in will be the sum of the entry from
the header plus the command line entry -s[] plus any
adjustment required by -v[]. The window start time is
picked up from the header while the window length is
picked up from the difference between -s[] and -e[].
For example, to hang a 1500ms window below a header
start time enter -e1500 on the command line. To hang a
1000ms window 500ms below a header defined start time
enter -s500 -e1500 on the command line. The output data
will have the first sample of the windowed data output
at sample 1. If you wish to have the data stay in its
prewindowed position enter -Z on the command line along
with the above parameters. You may also use -P or -v[]
at any time with this option. If no -hw[] entry is
present on the command line this option is ignored.
When using -hw[] the line header entry for TmMsFS will
NOT be updated.
-v vel
Enter a window start time adjustment velocity using the
units of your dataset. When using this option the win-
dow size will be a function of -s[] and -e[] [end time
- start time] and the window will slide along a line
defined by -v[]. For a simple 500ms window simply
default -s[] and use -e500. To slide the 500 ms window
down 300ms use a -s300 and -e800. You may use the -v[]
option in conjunction with -Z, -hw and -P to create all
kinds of wierd windowing. When used with -Z the data
remains in it's initial position. Without -Z the win-
dow start for any given trace is output at sample 1. If
you include -H on the command line the window start
will follow a hyperbolic trajectory using this velo-
city. If you enter a negative velocity the sign will
be carried in the arithmetic and the window start time
will increase from far to near offset. This mode can
be quite confusing with negative start times prevailent
over much of the spread. A little experimentation
might be required to understand how this affects your
data. When using -v[] the line header entry for TmMsFS
will NOT be updated.
-I ignore flag
Enter the command line argument '-I' to ignore any pre-
vious wind, i.e. it ignore whatever is in the TmMsFS
line header slot. This is useful if the input data was
windowed by some other data processing package and con-
verted to USP.
-P pass flag
Enter the command line argument '-P' to change the
meaning of the -ns, -ne, -rs, -re command line argu-
ments to ones of processing limits, with the rest of
the data passed unaffected. When using -P the line
header entry for TmMsFS will NOT be updated.
-H hyperbolic flag
Enter the command line argument '-H if you wish the
window start time to follow a hyperbolic trajectory
described using -s[] -e[] and -v[]. The default is to
ignore this option.
-Z verbose flag
Enter the command line argument '-Z' to zero out output
trace except for the windowed portion. This keeps the
original windowed data in the same position on the
trace. When using -Z the line header entry for TmMsFS
will NOT be updated. A negative start time is not
allowed with this option so if you are interested in
extracting a slab of data around a horizon gleaned from
a trace header [-hw option] you would want to use -P
instead of -Z. The output will be as you expect a
record of the original number of samples containing
live samples only within your window of interest.
-R restore flag
Enter the command line argument '-R' to undo a previous
wind. You must include the original command line argu-
ments. Not everything can be undone: if you push data
beyond the start or end of a trace and lose it it can-
not be restored.
-V verbose flag
Enter the command line argument '-V' to get additional
printout.
-? help flag
Enter the command line argument '-?' -h or -help
to get a help screen. The program stops after print-
ing.
EXAMPLES
An example of a basic window function limiting all traces to
global start and end times
wind -Ni_data -s1000 -e4000 -Oo_data
An example of outputting only live data between global start
and end times
wind -Ni_data -s1000 -e4000 -Oo_data -Z An
BUGS
Putting too slow a velocity may cause data to be lost off
the top of the traces with no warning. This can be dealt
with by including a negative start time (and perhaps also an
end time smaller than the original trace length). Testing of
these options is always recommended.
Some combinations of sample interval and windowing parame-
ters [usually including a -v entry] will result in problems
with integer conversion of sample position. This is not
generally a problem with forward windowing but may show up
as jitter should the data be restored using the -R option.
If you find this occuring you may need to use vred fol-
lowed by a simple window. The vred routine does an fft
shift of the trace as opposed to a simple integer sample
shift as is done in this routine.
AUTHOR
Paul Gutowski, pgutowski@amoco.com, socon 351-6043
Paul Garossino, pgarossino@amoco.com, socon 422-3932
COPYRIGHT
copyright 2001, Amoco Production Company
All Rights Reserved
an affiliate of BP America Inc.
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