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 ] [ -Ure-
dvel ] [ -Eazimuth/elevation ] [ -O ] [ -K ] [ -P ][ -V ]
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 pro-
jections will lead to unexpected results. Beware also that some parame-
ters 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]+[normal-
ize](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 for-
mat (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 .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 origin)
-Jmlon0/lat0/scale (Mercator - Give meridian and standard paral-
lel)
-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 Car-
ree))
-Jtlon0/scale (TM - Transverse Mercator, with Equator 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 manpages.
-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.
-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 positive). 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 arguments.
-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) gracefully, but this parameter
limits number of traces that the program attempts to read.
-U Apply reduction velocity by shifting traces upwards by red-
vel/|offset|. Negative velocity removes existing reduction.
Units should be consistent with offset in trace header and sam-
ple interval.
-E Azimuth and elevation for the 3-D projection.
-K More PostScript code will be appended later [Default terminates
the plot system].
-bo Selects binary output. Append s for single precision [Default is
double].
-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 distressing gener-
ality. 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(GMTMANSECTION), pssegy(GMTMANSECTION)
1 Jan 2004 PSSEGYZ(l)
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