pssegy(1) GMT pssegy(1)
NAME
pssegy - Plot a SEGY file on a map
SYNOPSIS
pssegy SEGYfile -Jparameters
-Rregion
-Ddeviation
-F[color] -W [ -Cclip ] [ -Eerror ] [ -I ] [ -K ] [ -Lnsamp ] [
-Mntrace ] [ -N ] [ -O ] [ -P ] [ -Q<mode><value> ] [ -Sheader ] [
-Tfilename ] [ -U[stamp] ] [ -V[level] ] [ -Xx_offset ] [ -Yy_off-
set ] [ -pflags ] [ -ttransp ]
Note: No space is allowed between the option flag and the associated
arguments.
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-spec-
ified) 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 signifi-
cant). 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 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 deter-
mines 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 a|)
Select map projection.
-Rwest/east/south/north[/zmin/zmax][+r][+uunit]
west, east, south, and north specify the region of interest, and
you may specify them in decimal degrees or in
[A+-]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. Appending +uunit expects projected (Carte-
sian) 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.
-F[color]
Fill trace (variable area, defaults to filling positive). Spec-
ify 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).
-Eerror
Allow error difference between requested and actual trace loca-
tions when using -T option.
-I Fill negative rather than positive excursions.
-K (more a|)
Do not finalize the PostScript plot.
-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.
-N Normalize trace by dividing by rms amplitude over full trace
length.
-O (more a|)
Append to existing PostScript plot.
-P (more a|)
Select aPortraita 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 (negative value
removes reduction already present).
-Qxmult to multiply trace locations by mult.
-Qydy to override sample interval in SEGY reel header.
-Sheader
Read trace locations from trace headers: header is either c for
CDP, o for offset, or bnum to read a long starting at byte num
in the header (first byte corresponds to num = 0). Default has
location given by trace number.
-Tfilename
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.
-U[[just]/dx/dy/][c|label] (more a|)
Draw GMT time stamp logo on plot.
-V[level] (more a|)
Select verbosity level [c].
-X[a|c|f|r][x-shift[u]]
-Y[a|c|f|r][y-shift[u]] (more a|)
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 a|)
Select perspective view.
-t[transp] (more a|)
Set PDF transparency level in percent.
-^ or just -
Print a short message about the syntax of the command, then
exits (NOTE: on Windows just use -).
-+ or just +
Print an extensive usage (help) message, including the explana-
tion 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 all options, then exits.
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 pssegy wa1.segy -JX5i/-5i -R0/100/0/10 -D1 -C3 -N -So -W -Fblack > 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,
use
gmt pssegy wa1.segy -JX5i/-5i -R0/100/0/10 -D1 -C3 -Sc -Qx0.1 -Fred -Qb-1 -I > segy.ps
SEE ALSO
gmt(1), pssegyz(1), segy2grd(1)
COPYRIGHT
2017, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe
5.4.2 Jun 24, 2017 pssegy(1)
gmt5 5.4.2 - Generated Thu Jun 29 15:47:22 CDT 2017