NAME

     pack3d  - (un)pack 3D pre/post stack data into common DI and
     common LI data constant width records

SYNOPSIS

     pack3d [ -Nntap ] [ -Ootap ] [ -R ] [ -S ]  [  -isinds  ]  [
     -idind ] [ -V ] [ -? ]

DESCRIPTION

     pack3d in forward mode  takes  3D  sorted  or  stacked  data
     (inline  or  crossline) and creates records each with a con-
     stant DI and LI, i.e.  all  the  traces  common  to  a  cell
     defined  by  (di,li)  coordinates.   For  prestack  data the
     number of output traces/rec will be equal to  the  CDP  fold
     defined  in  the  line header (line header word CDPFld) from
     the previous sort steps and partial records will  be  padded
     out  with dead traces.  The need here is that with either an
     inline or a crossline sort (primary  sort  index  LI  or  DI
     respectively)  the  secondary  sort  index  varies in number
     (subgather) as it changes in value so  that  processes  that
     need  to  operate on these subgathers have a problem if they
     expect constant width records.  pack3d is designed to  build
     constant width subgathers.  In the poststack case the number
     of traces/rec will be  taken  from  the  input  line  header
     (NumTrc).   A  gather or record in this case will be defined
     as one having a constant RecNum value in the trace headers.

     The data can now be operated on by most  2D  USP  processing
     tools and of course the emerging 3D tools.

     pack3d in reverse mode recreates the data order that  origi-
     nally went into pack3d.

  Command Line Parameters
     -N ntap
          Enter the input data set name or file immediately after
          typing  -N.  This output file is not required when pip-
          ing into the process.

     -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).

     -R   Enter the command line argument '-R' to undo a previous
          forward application of pack3d.

     -S   Enter the command line argument '-S' to operate on post
          stack  3D  data.  A gather or record here is defined as
          one having a common RecNum value. The secondary  header
          word  (varying  fastest)  can  be chosen on the command
          line.

     -is inds
          Enter the starting value of the header keyword used  to
          properly position live traces. Default = 1

     -id ind
          Enter the increment value of the header keyword used to
          properly position live traces. Default = 1

     -hw hdrwrd
          Enter the header key word mnemonic. Default = DphInd

     -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.

EXAMPLES

     1. inline sorted data

     sisort3d -Nxyz -nxyz.tbl -L | pack3d | ... | pack3d -R | ...

     2. crossline sorted data

     sisort3d -Nxyz -nxyz.tbl -D | pack3d | ... | pack3d -R | ...

     where "..." represents some process pipeline 2. regularizing
     3D stack data

     pack3d -Nstack -is700 -id1 -S | ...

     where "..." represents some downstream process pipeline. The
     default header word DphInd (or DI) is used to regularize the
     stacked traces within each record (Usually LI) starting from
     a  value  of 700 and incrementing by one up to the number of
     input traces per record.

BUGS

     For prestack input if you  change  the  major  sort  indices
     (LI's  &  DI's)  somewhere  between  the forward and reverse
     pack3d  you're basically dead.

SEE ALSO

     pad

AUTHOR

     Paul Gutowski, APR, zprg03@trc.amoco.com

COPYRIGHT

     copyright 2001, Amoco Production Company
               All Rights Reserved
          an affiliate of BP America Inc.