NAME

     at3d_lite  - at3d made easy; computes an arbitrary  traverse
     through  a stacked 3-D volume of data.  Traverse description
     comes from XSD pickfile.

SYNOPSIS

     at3d_lite [ -Nntap ]  [ -Ootap ]  [ -Ppicks ]  [ -iltsilts ]
     [ -xltsxlts ] [ -cdpintcdpint ] [ -V ] [ -h ]

DESCRIPTION

     at3d_lite constructs an arbitrary  traverse  through  a  3-D
     stacked  seismic  data  volume.  Unlike the  at3d, at3d_lite
     does not  allow  the  sophisticated  use  of  x,y  pairs  to
     describe  survey  corners and traverse vertices. Nor does it
     explicitely use LI,DI ranges  and  increments.   All  vertex
     control and relational survey information are retrieved from
     the xsd pick file.  The XSD pickfile is obtained by  picking
     the traverse on a time-slice extracted from the 3D volume by
     XSD.  The output cdp trace interval is user  defined.   Each
     output  trace  is  a  weighted  average  of the four nearest
     traces  in  the  3-D  volume  consequently  the  output   of
     at3d_lite often has an improved S/N ratio over the raw trace
     input.   The  character  and  amplitudes  of  the  data  are
     preserved  allowing one to construct a traverse that is both
     seamless and robust.  at3d_lite gets both its data  and  its
     parameters  from  command  line  arguments.  These arguments
     specify the input, output, the  XSD  pickfile,  the  inline,
     crossline  and  traverse trace spacing and verbose printout,
     if desired.

  Command line arguments
     -Nntap   [No Default: Pipe on stdin NOT ALLOWED]
          Enter the full path name of  the  file  containing  the
          input data set.

     -Ootap   [stdout:]
          Enter the full path name for the output file to receive
          the output data.

     -Pptap
          Enter the full path name for the XSD pickfile  contain-
          ing  the  arbitrary  traverse  turning points digitized
          from a time slice  extracted  from  the  input  dataset
          using  xsd .

     -iltsilts
          Enter the inline  trace  spacing  in  feet  of  meters.
          at3d_lite  assumes that each  usp  record is an inline.
          Consequently,  ilts   describes  the  discance  between
          traces of an input record. (default=25.0)


     -xltsxlts
          Enter the xline trace spacing.  This  is  the  distance
          between input records. (default=25.0)

     -cdpintcdpint
          Enter the output CMP interval (default=25.0).

     -V   Verbose printout  of  output  trace  coordinates,  both
          (x,y) and (li,di).

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

DISCUSSION

     This program is a modification of usp program at3d.   Unlike
     the  original  at3d,  at3d_lite does not allow the sophisti-
     cated use of  x,y  pairs  to  describe  survey  corners  and
     traverse  vertices. Nor does it explicitely use LI,DI ranges
     and increments.  All vertex control  and  relational  survey
     information are retrieved from the xsd pick file.

     XSD is used to extract a horizontal  slice  from  the  input
     volume and to pick the line of traverse.

SEE ALSO

     at3d

BUGS

     none known

AUTHOR

     - M.J. O'Brien (adapted from P.G.A. Garossino program  at3d)
     [July 1998: ATTC]

COPYRIGHT

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