NAME

     pssegy - Create imagemasked postscript from SEGY file


SYNOPSIS

     pssegy   SEGYfile    -Jparameters    -Rwest/east/south/north
     -F[rgb|gray]|-W  [ -I] [ -N ] [ -Bbias ] [ -Cclip ] [ -Z ] [
     -Xscale ] [ -Ysample int ]  [  -Sheader  ]  [  -Lnsamp  ]  [
     -Mntrace  ] [ -Uredvel ] [ -Tfilename ] [ -Eerror ] [ -O ] [
     -K ] [ -P ][ -V  ]


DESCRIPTION

     pssegy reads a native (IEEE) format SEGY file and produces a
     PostScript image of the seismic data. The imagemask operator
     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.

     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
          downward, 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, or b<num> to read a
          long starting at byte <num> in the header  (first  byte
          corresponds  to  num=0).  Default has location 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.

     -T   Plot only traces whose location corresponds to  a  list
          given in filename.  Order in which traces are listed is
          not significant - the entire space is checked for  each
          trace.

     -E   Allow error difference  between  requested  and  actual
          trace locations when using -T option.

     -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

     pssegy wa1.segy -JX5/-5 -R0/100/0/10 -C3 -N  -So  -W  -F0  >
     segy.ps

     To plot the SEGY file wa1.segy with traces plotted  at  true
     cdp*0.1,  clipped at +-3, with bias -1 and negative variable
     area shaded red, try

     pssegy wa1.segy -JX5/-5 -R0/100/0/10 -C3 -Sc -X0.1 -F255/0/0
     -B-1 -I > segy.ps



SEE ALSO

     gmt(l), pssegyz(l)