NAME

     nlx2lx - Non-linear to Linear X Coordinate System Transform

SYNOPSIS

     nlx2lx [-Nntap] [-NLMAPnlmap] [-Ootap]

     [-xminxmin] [-xmaxxmax] [-dxdx] [-fillfill] [-V] [-h]

DESCRIPTION

     nlx2lx transforms a dataset with a non-linear  X  coordinate
     system  to a dataset with a linear X coordinate system via a
     mapping function dataset.  The Y coordinate system (time  or
     depth for seismic data) is unchanged from input to output.

     X and Y are NOT survey coordinates.  X is the logical  coor-
     dinate  system  that is mapped to trace numbers and Y is the
     logical coordinate system that is mapped to  sample  numbers
     within a record.

     One (and only one) record in the  mapping  function  dataset
     must  conform  exactly  in  number of samples and traces per
     record to the records in the input non-linear X dataset that
     is  to  be  transformed.  The mapping function sample values
     describe the X coordinate of the coincident  sample  in  the
     input non-linear X record.

     An iso-Y search of the mapping function is made for  each  X
     coordinate  from the user specified output linear coordinate
     system.  If  found,  the  coincident  sample  in  the  input
     dataset  is moved to the output sample location. If the out-
     put X coordinate falls between samples in the mapping  func-
     tion, linear interpolation is applied to bounding input sam-
     ples to compute an output sample value.   If  the  output  X
     coordinate  falls outside the bounds of the mapping function
     a user specified fill value is output.

     This procedure is general purpose but was created to linear-
     ize  cubevz pick panels (which are output by program apkr in
     V(z) function number space) to a linear velocity space which
     makes  them look and feel like traditional velocity spectra.
     In this case the non-linear dataset is  cubevz  pick  panels
     from  program  apkr  and  the  mapping function dataset is a
     velocity model from program vmod or program vmodvavg.

  Command line arguments
     -Nntap
          Enter the name of the input  dataset  that  is  in  the
          non-linear  X  coordinate  system.  It can contain many
          records, but each record must contain the  same  number
          of traces per record and samples per trace as nlmap.

     -NLMAPnlmap
          Enter the name of the dataset that  contains  the  non-
          linear coordinate system mapping function. It must con-
          tain one record with the  same  number  of  traces  per
          record and samples per trace as ntap.

     -Ootap
          Enter the name of the output dataset that  will  be  in
          the linear X coordinate system.

     -xminxmin
          Enter the minimum X (feet  or  meters)  in  the  output
          linear X coordinate system.

     -xmaxxmax
          Enter the maximum X (feet  or  meters)  in  the  output
          linear X coordinate system.

     -dxdx
          Enter the delta X (feet or meters) in the output linear
          X  coordinate  system.  This, along with xmin and xmax,
          will determine the number of traces per record on  out-
          put.

     -fillfill
          Enter the output sample value to fill in when a  sample
          in  the  linear  X  coordinate system falls outside the
          bounds of the mapping function. (default = 1.0)

     -V   Enter -V for a verbose printout.

     -h   Enter -h for a terse help description.

SEE ALSO

     cubevz, vmod, vmodvavg, apkr.flow, apkr, mbs

BUGS

     None known.

AUTHOR

     David Nelson, APR

COPYRIGHT

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