NAME
rad2slnt - resample constant ray parameter records (radonf)
to constant angle records (slnt) (or reverse)
SYNOPSIS
rad2slnt [ -Nntap ] [ -Ootap ] [ -TV ] [ -vvtap ] [ -R ] [
-rvvref ] [ -saangs ] [ -eaange ] [ -dadang ] [ -mvvmute ] [
-spdxrec ] [ -xmxmax ] [ -V ] [ -? ]
DESCRIPTION
rad2slnt (1) resamples plane wave records in space between a
constant ray parameter (p) grid and a constant angle (gamma)
grid using a cubic spline interpolator and assuming constant
velocity, or (2) resample to angle assuming a time varying
velocity. The default direction is to go from the output of
radonf ... -L to equivalent slnt output (i.e. from ray
parameter to angle) for further streaming into the plane
wave MBS world.
In time varying mode the forward output will be of the form
where given trace represents the emergence angle at the sur-
face and that same angle of reflection at any later time,
e.g. a trace sample might be 60deg at the surface (time =
0ms) and at 1sec the sample there would be also from a 60deg
reflection. This for of output permits radonf output to be
interpolated so that constant angle (angst-type) stacks can
be computed.
In default mode the assumption is that one has the same
number of traces per record on output and that the only
change is the resampling. All header words should be filled
out correctly for MBS processing.
rad2slnt gets both its data and its parameters from command
line arguments. These arguments specify the input, output,
optional start and end angles and angle increment, and ver-
bose 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).
-sa angs
Enter the optional start angle in degrees. The default
is to grab line header entries written by radonf to
compute the angle information in the forward direction.
This option not valid if the time varying mode is
chosen.
-ea ange
Enter the optional end angle in degrees. The default
is to grab line header entries written by radonf to
compute the angle information in the forward direction.
This option not valid if the time varying mode is
chosen.
-da dang
Enter the optional angle increment in degrees. The
default is to grab line header entries written by
radonf to compute the angle information in the forward
direction. This option not valid if the time varying
mode is chosen.
-rv vref
Enter the optional reference velocity. The default is
to grab line header entries written by radonf to com-
pute this value. This option not valid if the time
varying mode is chosen.
-mv vmute
Enter the mute velocity. Currently all that happens
is this value gets written into the output line header.
This option not valid if the time varying mode is
chosen.
-sp dxrec
Enter the spacing between plane wave records. This and
the ray parameter is used to compute a time shift along
the line. The value is written into the static word of
the trace header (StaCor). This option not valid if the
time varying mode is chosen.
-xm xmax
For reverse (-R) mode enter maximum absolute offset
(ft,m). This option not valid if the time varying mode
is chosen.
-TV Enter the command line argument '-TV' to do the time
varying interpolation so that each output trace
represents reflections from a specific angle regardless
of time. A velocity file in velocity tape format - one
velocity trace per input record - must be given.
-v vtap
For the time varying option enter the name of the velo-
city tape. There must be one velocity trace per input
record.
-R Enter the command line argument '-R' to run the program
in reverse mode: go from constant angle sampling in
space (slnt) to constant ray parameter sampling
(radonf). Currently it is good practice to tell
rad2slnt exactly what angles are in the data and the
increment.
-V Enter the command line argument '-V' to get additional
printout.
-? Enter the command line argument '-?' to get online
help. The program terminates after the help screen is
printed.
EXAMPLE
1) A forward run converting from constant ray parameter to
SLNT format
rad2slnt -Nradonf_in -Oslnt_out
here the program will compute the start and end angles with
the increment.
2) A reverse run from SLNT format data to radonf format
data. rad2slnt -Nslnt_in -Oradonf_out -sa0 -ea90 -da.351
-xm25600
here the angle information has been input explicitly to
avoid possible problems extracting this info from the
headers. In any case the maximum absolute offset must be
filled in. 3) A forward run converting from constant ray
parameter to constant angle records rad2slnt -Nradonf_in
-Oangst_out -vvel_file -TV
where the output will now be constant angles. The velocity
file must be supplied for this option.
BUGS
unkonwn
SEE ALSO
slnt (mbs), radonf, radonr, taupnmo, taupspec, taupred,
angst
AUTHOR
Paul Gutowski, APR May 1993
COPYRIGHT
copyright 2001, Amoco Production Company
All Rights Reserved
an affiliate of BP America Inc.
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