## NAME

           pssegyz - Create imagemasked postscript from SEGY file

## SYNOPSIS

           pssegyz   SEGYfile   -Jparameters  -Rwest/east/south/north
           -Ddeviation -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 pro
           duces a PostScript image of the seismic data.  The  image
           mask 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 prin
           ciple 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-stan
           dard  meanings, and a couple of the options for pssegy are
           not available in pssegyz.  Note that the order  of  opera
           tions  before  the  seismic  data  are  plotted  is devia
           tion*[clip]([bias]+[normalize](sample  value)).  Deviation
           determines  how  far  in  the  plot coordinates a [normal
           ized][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 samples 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 UNIT/degree,
                  1:xxxxx, or width in UNIT  (upper  case  modifier).
                  UNIT  is  cm,  inch,  or  m,  depending on the MEA
                  SURE_UNIT setting in .gmtdefaults, but this can  be
                  overridden  on the command line by appending the c,
                  i, or m to the scale/width value.

                  CYLINDRICAL PROJECTIONS:

                  -Jclon0/lat0/scale (Cassini)
                  -Jjlon0/scale (Miller)
                  -Jmscale (Mercator - Greenwich and Equator as  ori
                  gin)
                  -Jmlon0/lat0/scale  (Mercator  -  Give meridian and
                  standard parallel)
                  -Joalon0/lat0/azimuth/scale  (Oblique  Mercator   -
                  point and azimuth)
                  -Joblon0/lat0/lon1/lat1/scale  (Oblique  Mercator -
                  two points)
                  -Joclon0/lat0/lonp/latp/scale (Oblique  Mercator  -
                  point and pole)
                  -Jqlon0/scale  (Equidistant  Cylindrical Projection
                  (Plate Carree))
                  -Jtlon0/scale (TM - Transverse Mercator, with Equa
                  tor as y = 0)
                  -Jtlon0/lat0/scale  (TM  - Transverse Mercator, set
                  origin)
                  -Juzone/scale (UTM - Universal Transverse Mercator)
                  -Jylon0/lats/scale (Basic Cylindrical Projection)

                  AZIMUTHAL PROJECTIONS:

                  -Jalon0/lat0/scale (Lambert).
                  -Jelon0/lat0/scale (Equidistant).
                  -Jflon0/lat0/horizon/scale (Gnomonic).
                  -Jglon0/lat0/scale (Orthographic).
                  -Jslon0/lat0/[slat/]scale (General Stereographic)

                  CONIC PROJECTIONS:

                  -Jblon0/lat0/lat1/lat2/scale (Albers)
                  -Jdlon0/lat0/lat1/lat2/scale (Equidistant)
                  -Jllon0/lat0/lat1/lat2/scale (Lambert)

                  MISCELLANEOUS PROJECTIONS:

                  -Jhlon0/scale (Hammer)
                  -Jilon0/scale (Sinusoidal)
                  -Jk[f|s]lon0/scale (Eckert IV (f) and VI (s))
                  -Jnlon0/scale (Robinson)
                  -Jrlon0/scale (Winkel Tripel)
                  -Jvlon0/scale (Van der Grinten)
                  -Jwlon0/scale (Mollweide)

                  NON-GEOGRAPHICAL PROJECTIONS:

                  -Jp[a]scale[/origin]  (polar (theta,r) coordinates,
                  optional a for azimuths and offset theta [0])
                  -Jxx-scale[l|ppow][/y-scale[l|ppow]] (Linear,  log,
                  and power scaling)
                  More  details  can  be  found in the psbasemap man
                  pages.

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

           -D     gives the deviation in X units of the plot for  1.0
                  on  the  scaled  trace, This may be a single number
                  (applied  equally  in  X  and  Y   directions)   or
                  devX/devY

           -F[rgb|gray]
                  Fill trace (variable area, defaults to filling pos
                  itive). 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)  grace
                  fully,  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
           plotted at true offset locations, clipped at +-3 and  with
           wiggle  trace and positive variable area shading in black,
           try

           pssegyz   wa1.segy    -JX5/-5    -D1    -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)

                               15 Oct 2001                 PSSEGYZ(l)