pssegyz
pssegyz - Create imagemasked postscript from SEGY file
Synopsis
pssegyz SEGYfile -Jparameters
-Jz|Zparameters
-Rwest/east/south/north[/zmin/zmax][r]
-Ddeviation -F[color] -W
[ -Cclip ]
[ -I ] [ -K ] [ -Lnsamp ]
[ -Mntrace ]
[ -N ]
[ -O ]
[ -P ]
[ -Q<mode><value> ]
[ -Sheader_x/header_y ]
[ -U[just/dx/dy/][c|label] ]
[ -V[level] ]
[ -Xx_offset ]
[ -Yy_offset ]
[ -Z ]
[ -p<flags> ]
[ -t<transp> ]
Note: No space is allowed between the option flag and the associated arguments.
Description
pssegyz 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
principle any map projection may be used, however it is likely that the
geographic projections will lead to unexpected results. Beware that 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 coordinates 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 (i.e., 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).
Required Arguments
- SEGYfile
- Seismic SEGY data set to be imaged.
- -Jparameters (more ...)
- Select map projection.
- -R[unit]west/east/south/north[/zmin/zmax][r]
- west, east, south, and north specify the region of interest,
and you may specify them in decimal degrees or in
[+-]dd:mm[:ss.xxx][W|E|S|N] format. Append r if lower left
and upper right map coordinates are given instead of w/e/s/n. The
two shorthands -Rg and -Rd stand for global domain (0/360
and -180/+180 in longitude respectively, with -90/+90 in latitude).
Alternatively for grid creation, give Rcodelon/lat/nx/ny, where
code is a 2-character combination of L, C, R (for left, center, or right)
and T, M, B for top, middle, or bottom. e.g., BL for lower left. This
indicates which point on a rectangular region the lon/lat coordinate
refers to, and the grid dimensions nx and ny with grid spacings via
-I is used to create the corresponding region.
Alternatively, specify the name of an existing grid file and the
-R settings (and grid spacing, if applicable) are copied from
the grid. Using -Runit expects projected (Cartesian)
coordinates compatible with chosen -J and we inversely project
to determine actual rectangular geographic region.
For perspective view (-p), optionally append /zmin/zmax.
In case of perspective view (-p), a z-range (zmin, zmax)
can be appended to indicate the third dimension. This needs to be
done only when using the -Jz option, not when using only the
-p option. In the latter case a perspective view of the plane is
plotted, with no third dimension.
- -Ddeviation
- 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 the pair devX/devY.
- -F[color]
- Fill trace (variable area, defaults to filling positive). Specify the
color with which the imagemask is filled.
- -W
- Draw wiggle trace.
You must specify at least one of -W and -F.
Optional Arguments
- -A
- Flip the default byte-swap state (default assumes data have a
bigendian byte-order).
- -Cclip
- Sample value at which to clip data (clipping is applied to both
positive and negative values).
- -I
- Fill negative rather than positive excursions.
- -K (more ...)
- Do not finalize the PostScript plot.
- -Lnsamp
- 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).
- -Mntrace
- 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.
- -N
- Normalize trace by dividing by rms amplitude over full trace length.
- -O (more ...)
- Append to existing PostScript plot.
- -P (more ...)
- Select “Portrait” plot orientation.
- -Q<mode><value>
- Can be used to change 5 different settings depending on mode:
-Qbbias to bias scaled traces (-Qb-0.1 subtracts 0.1 from values).
-Qidpi sets the dots-per-inch resolution of the image [300].
-Quredvel to apply reduction velocity (-ve removes reduction already present).
-Qxmult to multiply trace locations by mult.
-Qydy to override sample interval in reel header.
- -Sheader_x/header_y
- Read trace locations from trace headers: headers 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.
- -U[just/dx/dy/][c|label] (more ...)
- Draw GMT time stamp logo on plot.
- -V[level] (more ...)
- Select verbosity level [c].
-X[a|c|f|r][x-shift[u]]
- -Y[a|c|f|r][y-shift[u]] (more ...)
- Shift plot origin.
- -Z
- Do not plot traces with zero rms amplitude.
- -p[x|y|z]azim/elev[/zlevel][+wlon0/lat0[/z0]][+vx0/y0] (more ...)
- Select perspective view.
- -t[transp] (more ...)
- Set PDF transparency level in percent.
- -^ or just -
- Print a short message about the syntax of the command, then exits (NOTE: on Windows use just -).
- -+ or just +
- Print an extensive usage (help) message, including the explanation of
any module-specific option (but not the GMT common options), then exits.
- -? or no arguments
- Print a complete usage (help) message, including the explanation of
options, then exits.
- --version
- Print GMT version and exit.
- --show-datadir
- Print full path to GMT share directory and exit.
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, use
gmt pssegyz wa1.segy -JX5i/-5i -D1 -Jz0.05i -E180/5 -R0/100/0/10/0/10 \
-C3 -N -So -W -Fblack > segy.ps
Bugs
Variable area involves filling four-sided figures of distressing
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.