NAME

     road_kill  - Robust Objective Amplitude Deviation Kill  pro-
     gram.   This  module  is  designed for amplitude editing and
     quality control via a robust statistical nonstationary, time
     and  space analysis.  The module will either flag  traces as
     dead     or     repair      necessary      windows      with
     interpolation/extrapolation or zero the bad window.

SYNOPSIS

     road_kill [ -Nntap ] [ -Ootap ] [  -sist  ]  [  -eiend  ]  [
     -rsrecstart  ] [ -rerecend ] [ -nstrcstart ] [ -netrcend ] [
     -winwindow ] [ -numnumber ] [ -I ] [ -Z ] [ -qc ] [ -V  ]  [
     -h, -? ]

DESCRIPTION

     road_kill uses a statistical approach on user  defined  win-
     dows   of  data to determine a degree of commonality between
     adjacent traces.  If the central trace in any  window  fails
     to  be  common  to  its surrounding traces then the trace is
     either  flagged  dead  (30000  in  StaCor)  or  repaired  by
     interpolation/extrapolation  (extrapolation if the bad trace
     is the first or last trace).  And now, an all new, zero  the
     bad  data  window (-Z) option.  The data should be amplitude
     balanced with at least a  reasonable  single   NMO  function
     applied  to the data to ensure regularization of the data in
     time and space.  The NMO function can be on the  same  order
     as  what  would be used during data interpolation as is pro-
     gram zombie.

     road_kill allows the user to define the window  lengths  for
     analysis  though  1000  ms seems to be most reasonable.  The
     user may also define the maximum number of traces away  from
     the  central  trace  that the module can use in the analysis
     when it finds adjacent dead traces.

     When the module runs with -I on command line the module will
     interpolate over bad areas of data else the module will flag
     the trace as dead.  The module can  also  write  a  standard
     ascii file of record and trace numbers that have been killed
     or repaired.  The output file has the  input  filename  with
     the  suffix  _QC.   This  file can be plotted with xgraph or
     plotxy and viewed for patterns.

     road_kill gets both its data and its parameters from command
     line  arguments.  These arguments specify the input, output,
     the analysis window, maximum number of traces away to  allow
     for  analysis,   interpolation  option, qc option(though you
     should always do this), 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).

     -s ist
          Enter the global start time (or depth) of the  replace-
          ment.  Default = trace start.

     -e iend
          Enter the global end time (or depth)  of  the  replace-
          ment.  Default = trace end.

     -rs ist
          Enter the starting  record  number.   Default  =  first
          record.

     -re iend
          Enter the ending record number.  Default = last record.

     -ns ist
          Enter the  starting  trace  number.   Default  =  first
          trace.

     -ne iend
          Enter the ending trace number.  Default = last trace.

     -win window length
          Enter the analysis widow length.  Default = 1000 ms.

     -numnumber traces
          Enter the maximum allowable number of traces away  from
          the  central  trace  that  can  be  used  for analysis.
          Default = 3

     -I   Enter the command line  argument  '-I'  to  enable  the
          interpolation/extrapolation option.

     -Z   Enter the command line argument '-Z' to  zero  the  bad
          data window.

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

DISCUSSION

     This program was designed so  that  the  user  could  do  an
     effective  amplitude  editing  and  QC  on  a trace by trace
     basis.  It takes advantage of  nonstationarity  and  spacial
     relationships  of  data  as well as time.  The best mode for
     using road_kill is to input data with at least an NMO  func-
     tion which the user would consider accurate enough for trace
     interpolation.  The NMO with some type of amplitude  balance
     on  the  traces  regularizes the data enough so that a trace
     comparison in time and space is valid.

     The module goes through a series of  calculations  for  each
     trace and window: maximum, average, standard deviation, max-
     imum average deviation, area, and  kurtosis  (see  Numerical
     Recipes).   Through  a comparison process, each trace window
     is compared to its nearest spacial neighbor of common  time.
     Through comparison of the statistics, the data is determined
     to have an anomaly or not.

     If a problem is detected, the module will default  to   kil-
     ling  the  trace  by putting 30000 in the StaCor header word
     (not actually zeroing the time series).  If the user wants a
     fix  to the problem, the module will interpolate the offend-
     ing window of data only, not the entire trace.

     With the -qc option the  user  can  get  an  ascii  file  of
     records and traces killed.  This is to provide the user with
     additional QC of this process.  A simple xgraph of the  file
     will   show   the  user  the  distribution  of  record/trace
     kills/repairs.  It is always recommended that this  be  done
     in addition to viewing the output results.

BUGS

     unknown

ALSO SEE

     skill, tfskill, zombie, bdnmo, ttothen, slicetrp

AUTHOR

     James M. Gridley

COPYRIGHT

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