NAME

     cotaper  - apply tapers  to  seismic  data  to  improve  the
     appearance of common offset migration sections.

SYNOPSIS

     taper [ -Nfile_in  ]  [  -Gfile_geom  ]  [  -Ofile_out  ]  [
     -Wfile_wgt  ]  [  -xtaperxtaper  ] [ -dcrpdcrp ] [ -doffset-
     doffset ] [ -V ] [ -? ]

DESCRIPTION

     cotaper C will apply a spatial taper (ramp) to seismic  data
     to  minimize the migration 'wings' due to finite aperture or
     missing data, as often  occurs  in  spliced  lines  obtained
     using  different acquisition parameters. First the distribu-
     tion of the seismic  data  is  determined  by  binning  them
     according to its $( x sub m , x sub h )$ distribution, where
     the midpoint,

     $ x sub m ={x sub s + x sub r } over 2 $,

     and the offset,

      $ x sub h = x sub s - x sub r $ .

     Here,

     $ x sub s $ is the shot position,  and

     $ x sub r $ is the receiver position.

     If we now make the following definitions:

     $c sub {m,h} $ = the number of live traces in a bin centered
     about $(x sub m , x sub h )$, and

     $ c bar$ = the average number of live traces per bin,

     then we can define the weight (or taper) for the  traces  in
     bin (m,h), $ w sub {m,h} $ by:

     $ w sub {m,h} = sum from {j=-J} to {j=+J} c sub  m+j,h  over
     {(2J+1) c bar}$

     where

     J=xtaper/(2*dcrp) as defined by the command  line  arguments
     below.


  Command line arguments
     -Nfile_in
          Enter the full path name of  the  file  containing  the
          input  USP  format  common  shot data set.  The program
          will give an error message if the input  file  is  read
          protected.   If no input file is given, and there is no
          standard input, the program  will  hang.   (default  is
          standard in ).

     -Ofile_out
          Enter the full path name for the output  tapered  file.
          If not specified, the output will be directed to  stan-
          dard out.

     -Gfile_geom
          Enter the full path name of the geometry file, as  cal-
          culated by program prepmig (No Default).  )

     -Wfile_wgt
          Enter the full  path  name  of  the  (optional)  output
          weight file. The weights will be stored in a USP format
          file   with   the   sample    number    varying    from
          (mincrp,maxcrp)  while  the trace number will vary from
          (minoffset,maxoffset), where the limits are  calculated
          from information in file_geom, dcrp and  doffset.

     -xtaperxtaper
          Enter the taper distance in m (ft) to be applied in the
          common offset direction.

     -dcrpdcrp
          Enter the crp (common reflection point) increment to be
          used  in binning the data (Default: dcrp=dsta read from
          file_geom).

     -doffsetdoffset
          Enter the offset increment to be used  in  binning  the
          data (Default: doffset=2.*dsta read from file_geom).

     -V   Verbose mode.  All parameters from the command line and
          lineheader will be sent to standard error output.

     -?   Query mode.   With  this  flag,  cotaper  will  send  a
          description  of the command line arguments to the stan-
          dard error output and stop.

BUGS

     None known.

SEE ALSO

     prepmig, sammig, taper

DEVELOPMENT AGREEMENT

     USP Core Product Line (P-95-7518). Thank you for  your  sup-
     port!

AUTHOR:

      K. J. Marfurt (EPTG, Tulsa, 1995).  ~