NAME

     pssegyz - Create imagemasked postscript from SEGY file


SYNOPSIS

     pssegyz   SEGYfile   -Jparameters    -Rwest/east/south/north
     -F[rgb|gray]|-W  [ -I] [ -N ] [ -Bbias ] [ -Cclip ] [ -Z ] [
     -Xscale ] [ -Ysample int ] [ -Sheader_x/header_y ] [ -Lnsamp
     ] [ -Mntrace ] [ -Uredvel ] [ -Eazimuth/elevation ] [ -O ] [
     -K ] [ -P ][ -V  ]


DESCRIPTION

     pssegyz reads a native (IEEE) format SEGY file and  produces
     a PostScript image of the seismic data. The imagemask opera-
     tor is used so that the seismic data are plotted as a  1-bit
     deep  bitmap  in  a  single  (user-specified)  color or gray
     shade, with a transparent background.  The bitmap resolution
     is  taken from the current GMT defaults.  The seismic traces
     may be plotted at their true locations using information  in
     the  trace headers (in which case order of the traces in the
     file is not significant).
      Standard GMT geometry routines are used so that in  princi-
     ple  any  map  projection  may be used, however it is likely
     that the geographic  projections  will  lead  to  unexpected
     results.  Beware also that some parameters have non-standard
     meanings, and a couple of the options  for  pssegy  are  not
     available in pssegyz.

     Note that the order of operations before  the  seismic  data
     are  plotted  is  deviation*[clip]([bias]+[normalize](sample
     value)). Deviation determines how far in  the  plot  coordi-
     nates  a  [normalized][biased][clipped]  sample  value  of 1
     plots from the trace location.

     The SEGY file should be a disk image of the tape format  (ie
     3200  byte  text  header,  which is ignored, 400 byte binary
     reel header, and 240 byte header for each trace)  with  sam-
     ples  as  native  real*4  (IEEE real on all the platforms to
     which I have access)

     SEGYfile
          Seismic data set to be imaged

     -J   Selects  the  map  projection.  Scale  is  inch/degree,
          1:xxxxx, or width in inch (upper case modifier).

          NON-GEOGRAPHICAL PROJECTIONS:

          -Jpscale (Linear projection for polar (theta,r) coordi-
          nates)
          -Jxx-scale[l|ppow][/y-scale[l|ppow]] (Linear, log,  and
          power scaling)
          More details can be found in  the  psbasemap  manpages.
          For  seismic  plots where time or depth increases down-
          ward, use a negative y-scale

     -R   west, east, south, and  north  specify  the  Region  of
          interest.  To specify boundaries in degrees and minutes
          [and seconds], use the dd:mm[:ss] format.  Append r  if
          lower  left  and  upper right map coordinates are given
          instead of wesn.

     -F[rgb|gray]
          Fill trace (variable area, defaults  to  filling  posi-
          tive).  rgb  or  gray  gives  the  color with which the
          imagemask is filled.

     -W   Draw wiggle trace.

      Must specify at least one of -W and -F.


OPTIONS

     No space between the option flag and  the  associated  argu-
     ments.

     -I   Fill negative rather than positive excursions.

     -N   Normalize trace by dividing by rms amplitude over  full
          trace length.

     -B   Bias to apply to data (added to sample values).

     -C   Sample value at which to clip data (clipping is applied
          to both positive and negative values).

     -Z   Don't plot traces with zero rms amplitude.

     -X   Multiply trace locations by scale before plotting.

     -Y   Override sample interval in reel header.

     -S   Read trace locations  from  trace  headers:  header  is
          either  c  for CDP, o for offset, b<num> to read a long
          starting at  byte  <num>  in  the  header  (first  byte
          corresponds to num=0), or a number to fix the location.
           First parameter for x, second for y. Default has X and
          Y given by trace number.

     -L   Override number of samples per  trace  in  reel  header
          (program  attempts  to determine number of samples from
          each trace header if possible  to  allow  for  variable
          length traces).

     -M   Override number of traces  specified  in  reel  header.
          Program  detects  end  of file (relatively) gracefully,
          but this parameter limits number  of  traces  that  the
          program attempts to read.

     -U   Apply reduction velocity by shifting traces upwards  by
          redvel/|offset|.   Negative  velocity  removes existing
          reduction. Units should be consistent  with  offset  in
          trace header and sample interval.

     -E   Azimuth and elevation for the 3-D projection.

     -K   More PostScript code will be  appended  later  [Default
          terminates the plot system].

     -O   Selects Overlay plot mode [Default  initializes  a  new
          plot system].

     -P   Selects  Portrait  plotting  mode   [GMT   Default   is
          Landscape, see gmtdefaults to change this].

     -V   Selects verbose mode, which will send progress  reports
          to stderr [Default runs "silently"].



EXAMPLES

     To plot the SEGY file wa1.segy with normalized traces  plot-
     ted at true offset locations, clipped at +-3 and with wiggle
     trace and positive variable area shading in black, try

     pssegyz wa1.segy -JX5/-5 -Jz0.05  -E180/5  -R0/100/0/10/0/10
     -C3 -N -So -W -F0 > segy.ps



BUGS

     Variable area involves filling four-sided  figures  of  dis-
     tressing  generality.   I know that some of the more complex
     degenerate cases are not dealt with correctly or at all; the
     incidence  of  such cases increases as viewing angles become
     more oblique, and  particularly  as  the  viewing  elevation
     increases. Wiggle-trace plotting is not affected.



SEE ALSO

     gmt(l), pssegy(l)