pssegyz
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 SEGY file with samples represented as IEEE
real 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 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 IEEE real*4.It is assumed
that the file has big-endian byte order (eg Sun systems)
and bytes are swapped on reading for little-endian plat
forms.
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
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.
-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.
by redvel/|offset|. Negative velocity removes
existing reduction. Units should be consistent with
offset in trace header and sample interval.
-A Reverse standard byte-swapping behaviour (ie byte-
order of the SEGY file is little-endian).
-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 ele
vation increases. Wiggle-trace plotting is not affected.
SEE ALSO
gmt(l), pssegy(l)
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