NAME¶
pssegyz - Create imagemasked postscript from SEGY file
SYNOPSIS¶
pssegyz SEGYfile -Jparameters
-Jz|
Zparameters
-Rwest/
east/
south/
north[/
zmin/
zmax][
r]
-Ddeviation
-F[
rgb|
gray]|
-W [
-Bbias ] [
-C clip ] [
-Eazim/
elev[
+wlon/
lat[/
z]][
+vx0/
y0] ] [
-I ] [
-K ] [
-Lnsamp ] [
-Mntrace ] [
-N ]
[
-O ] [
-P ] [
-Sheader_x/
header_y ] [
-U redvel ] [
-V ] [
-Xscale ] [
-Ysample_int ] [
-Z ]
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 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 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 (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
MEASURE_UNIT setting in .gmtdefaults4, but this can be overridden
on the command line by appending c, i, or m to the
scale/width value. When central meridian is optional, default is center of
longitude range on -R option. Default standard parallel is the
equator. For map height, max dimension, or min dimension, append h,
+, or - to the width, respectively.
More details can be found in the psbasemap man pages.
CYLINDRICAL PROJECTIONS:
-Jclon0/lat0/scale (Cassini)
-Jcyl_stere/[lon0/[lat0/]]scale (Cylindrical
Stereographic)
-Jj[lon0/]scale (Miller)
-Jm[lon0/[lat0/]]scale (Mercator)
-Jmlon0/lat0/scale (Mercator - Give meridian and standard
parallel)
-Jo[a]lon0/lat0/azimuth/scale (Oblique Mercator -
point and azimuth)
-Jo[b]lon0/lat0/lon1/lat1/scale (Oblique Mercator -
two points)
-Joclon0/lat0/lonp/latp/scale (Oblique Mercator - point and
pole)
-Jq[lon0/[lat0/]]scale (Cylindrical
Equidistant)
-Jtlon0/[lat0/]scale (TM - Transverse Mercator)
-Juzone/scale (UTM - Universal Transverse Mercator)
-Jy[lon0/[lat0/]]scale (Cylindrical Equal-Area)
CONIC PROJECTIONS:
-Jblon0/lat0/lat1/lat2/scale (Albers)
-Jdlon0/lat0/lat1/lat2/scale (Conic Equidistant)
-Jllon0/lat0/lat1/lat2/scale (Lambert Conic Conformal)
-Jpoly/[lon0/[lat0/]]scale ((American)
Polyconic)
AZIMUTHAL PROJECTIONS:
-Jalon0/lat0[/horizon]/scale (Lambert Azimuthal
Equal-Area)
-Jelon0/lat0[/horizon]/scale (Azimuthal
Equidistant)
-Jflon0/lat0[/horizon]/scale (Gnomonic)
-Jglon0/lat0[/horizon]/scale (Orthographic)
-Jglon0/lat0/altitude/azimuth/tilt/twist/Width/Height/scale
(General Perspective).
-Jslon0/lat0[/horizon]/scale (General
Stereographic)
MISCELLANEOUS PROJECTIONS:
-Jh[lon0/]scale (Hammer)
-Ji[lon0/]scale (Sinusoidal)
-Jkf[lon0/]scale (Eckert IV)
-Jk[s][lon0/]scale (Eckert VI)
-Jn[lon0/]scale (Robinson)
-Jr[lon0/]scale (Winkel Tripel)
-Jv[lon0/]scale (Van der Grinten)
-Jw[lon0/]scale (Mollweide)
NON-GEOGRAPHICAL PROJECTIONS:
-Jp[a]scale[/origin][r|z] (Polar
coordinates (theta,r))
-Jxx-scale[d|l|ppow|t|T][
/y-scale[d|l|ppow|t|T]]
(Linear, log, and power scaling)
- -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, specify the name of an existing grid file and the -R
settings (and grid spacing, if applicable) are copied from the grid.
- -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
- -E
- Sets the viewpoint's azimuth and elevation (for perspective view)
[180/90]. For frames used for animation, you may want to append +
to fix the center of your data domain (or specify a particular world
coordinate point with +wlon0/lat[/z]) which
will project to the center of your page size (or specify the coordinates
of the projected view point with +vx0/y0).
- -F[rgb|gray]
- Fill trace (variable area, defaults to filling positive). rgb or gray
gives the color with which the imagemask is filled.
- -W
- Draw wiggle trace.
- You must specify at least one of -W and -F.
OPTIONS¶
No space between the option flag and the associated arguments.
- -A
- Flip the default byte-swap state (default assumes data have a bigendian
byte-order).
- -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).
- -I
- Fill negative rather than positive excursions.
- -K
- More PostScript code will be appended later [Default terminates the
plot system].
- -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
- Selects Overlay plot mode [Default initializes a new plot system].
- -P
- Selects Portrait plotting mode [Default is Landscape, see
gmtdefaults to change this].
- -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.
- -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.
- -V
- Selects verbose mode, which will send progress reports to stderr [Default
runs "silently"].
- -X
- Multiply trace locations by scale before plotting.
- -Y
- Override sample interval in reel header.
- -Z
- Do not plot traces with zero rms amplitude.
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
pssegyz wa1.segy
-JX 5/-5
-D 1
-Jz 0.05
-E
180/5
-R 0/100/0/10/0/10
-C 3
-N -S o
-W
-F black > 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.
SEE ALSO¶
GMT(1),
pssegy(1)