NAME

     psdm3d  - module to stretch and squeeze seismic  data  based
     on a (horizon,datum) model.

SYNOPSIS

     psdm3d [ -Nntap ] [ -Ootap ] [ -Ppik ] [ -nsnstr ] [ -nenetr
     ]  [ -rsnrst ] [ -renred ] [ -fmaxhz ] [ -tstscl ] [ -linear
     ] [ -R ] [ -V ] [ -? ]

DESCRIPTION

     psdm3d stretches and squeezes the data based upon  an  input
     model extracted from the trace header.  The horizon informa-
     tion must be in trace header entries TVPT01  ...  21,  while
     the corresponding datum times are extraced from trace header
     words TVPV01 ... 21.  [See program lmhorizon] A  maximum  of
     21  horizon,datum pairs are allowed.  This approach has been
     used to move events to a desired spatial position  prior  to
     filtering.   The  program  has  an  inverse option to return
     stretched-squeezed data to its original sample position.

     Provision is made for data that are fairly coarsely sampled:
     an  optional  time scale factor can be input from either the
     cmd line or retrieved from the line header entry  T_Unit  of
     the  input  data.  Since  horizon times and their datums are
     stored in the short integer trace words TVPTxx and TVPVxx no
     decimal values can be used. However an upstream program like
     tim2hed3d can multiply these  times  by  some  value  >  1.0
     allowing  some  fractional  part to be stored as an integer.
     psdm3d then divides all horizon  and  datum  times  by  this
     scale factor internally and then uses them as floating point
     values with fractional parts. If the program detects  a  non
     zero T_Unit value the program will announce the fact to both
     the printout file and stderr.

     psdm3d was designed originally to be used  on  stacked  data
     sets  to aid in multiple removal.  More recently it has been
     used on common offset sections to aid in multiple removal on
     prestack data.

     For each trace, the first sample remains fixed and the  last
     sample  remains  fixed.  All other samples are stretched and
     squeezed according to the  input  model.   Because  of  this
     stretching and squeezing, the temporal frequency of the data
     will change and could result in violations of  the  sampling
     theorem.

     psdm3d retrieves its data and its  parameters  from  command
     line  arguments.  These arguments specify the input, output,
     the pick file, sample, trace and record start and  end,  the
     maximum  frequency  of  interest,  forward-inverse flag, and
     verbose printout flag.

  Command line arguments
     -N ntap   [Default: stdin]
          Enter the input data set name 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 dif-
          ferent directory.   Example  -N/b/vsp/dummy  tells  the
          program to look for file 'dummy' in directory '/b/vsp'.

     -O otap   [Default: stdout]
          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).

     -ns nstr   [Default: first trace of record]
          Enter the start trace number.

     -ne netr   [Default: last trace of record]
          Enter the end trace number.

     -rs nrst   [Default: first record of dataset]
          Enter start record number.

     -re nred   [Default: last record of dataset]
          Enter end record number.

     -fmax hz   [Default: option turned off]
          Enter the maximum frequency of interest  containted  in
          the dataset.  The routine will report to the print file
          any occurance of a squeeze that results  in  data  with
          frequencies  lower  than this being temporally aliased.
          This  parameter  is  not  required.   It  is  here  for
          tutorial purposes only.

     -ts tscl   [Default: option 1.0]
          Enter the time scale  factor  to  use  internally.  All
          TVPTxx and TVPVxx times will be divided by this factor.

     -R   Enter -R to remove the stretch-squeeze.  Omitting  this
          parameter will result in stretch/squeeze application.

     -linear
          Enter -linear to enable linear interpolation of  resul-
          tant  data  amplitudes.   Omitting  this parameter will
          result in the application of  cubic  spline  interpola-
          tion.

     -V   Enter the command line argument '-V' to get  additional
          printout.


     -?   Enter the command line  argument  '-?'  or  -h  to  get
          online  help.   The  program  terminates after the help
          screen is printed.

BUGS

     Unknown

SEE ALSO

      lmhorizon(1) fkkstrip(1) fftxy(1) polymute(1)

AUTHOR

     P.G.A.           Garossino,            July,            1993
     ,[APR:X3932:zpgg07@trc.amoco.com]