1PSSEGY(1) Generic Mapping Tools PSSEGY(1)
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6 pssegy - Create imagemasked postscript from SEGY file
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9 pssegy SEGYfile -Jparameters -Rwest/east/south/north[r] -Ddeviation
10 -F[rgb|gray]|-W [ -Bbias ] [ -Cclip ] [ -Eerror ] [ -I ] [ -K ] [
11 -Lnsamp ] [ -Mntrace ] [ -N ] [ -O ] [ -P ] [ -Sheader ] [ -Tfilename ]
12 [ -Uredvel ] [ -V ] [ -Xscale ] [ -Ysample int ] [ -Z ]
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15 pssegy reads a native (IEEE) format SEGY file and produces a PostScript
16 image of the seismic data. The imagemask operator is used so that the
17 seismic data are plotted as a 1-bit deep bitmap in a single (user-spec‐
18 ified) color or gray shade, with a transparent background. The bitmap
19 resolution is taken from the current GMT defaults. The seismic traces
20 may be plotted at their true locations using information in the trace
21 headers (in which case order of the traces in the file is not signifi‐
22 cant). Standard GMT geometry routines are used so that in principle
23 any map projection may be used, however it is likely that the geo‐
24 graphic projections will lead to unexpected results. Beware also that
25 some parameters have non-standard meanings. Note that the order of
26 operations before the seismic data are plotted is devia‐
27 tion*[clip]([bias]+[normalize](sample value)). Deviation determines how
28 far in the plot coordinates a [normalized][biased][clipped] sample
29 value of 1 plots from the trace location. The SEGY file should be a
30 disk image of the tape format (ie 3200 byte text header, which is
31 ignored, 400 byte binary reel header, and 240 byte header for each
32 trace) with samples as native real*4 (IEEE real on all the platforms to
33 which I have access)
34 SEGYfile
36 Seismic data set to be imaged
37 -J Selects the map projection. Scale is UNIT/degree, 1:xxxxx, or
39 width in UNIT (upper case modifier). UNIT is cm, inch, or m,
40 depending on the MEASURE_UNIT setting in .gmtdefaults4, but this
41 can be overridden on the command line by appending c, i, or m to
42 the scale/width value. When central meridian is optional,
43 default is center of longitude range on -R option. Default
44 standard parallel is the equator. For map height, max dimen‐
45 sion, or min dimension, append h, +, or - to the width, respec‐
46 tively.
47 More details can be found in the psbasemap man pages.
48 CYLINDRICAL PROJECTIONS:
50 -Jclon0/lat0/scale (Cassini)
52 -Jcyl_stere/[lon0/[lat0/]]scale (Cylindrical Stereographic)
53 -Jj[lon0/]scale (Miller)
54 -Jm[lon0/[lat0/]]scale (Mercator)
55 -Jmlon0/lat0/scale (Mercator - Give meridian and standard paral‐
56 lel)
57 -Jo[a]lon0/lat0/azimuth/scale (Oblique Mercator - point and
58 azimuth)
59 -Jo[b]lon0/lat0/lon1/lat1/scale (Oblique Mercator - two points)
60 -Joclon0/lat0/lonp/latp/scale (Oblique Mercator - point and
61 pole)
62 -Jq[lon0/[lat0/]]scale (Cylindrical Equidistant)
63 -Jtlon0/[lat0/]scale (TM - Transverse Mercator)
64 -Juzone/scale (UTM - Universal Transverse Mercator)
65 -Jy[lon0/[lat0/]]scale (Cylindrical Equal-Area)
66 CONIC PROJECTIONS:
68 -Jblon0/lat0/lat1/lat2/scale (Albers)
70 -Jdlon0/lat0/lat1/lat2/scale (Conic Equidistant)
71 -Jllon0/lat0/lat1/lat2/scale (Lambert Conic Conformal)
72 AZIMUTHAL PROJECTIONS:
74 -Jalon0/lat0[/horizon]/scale (Lambert Azimuthal Equal-Area)
76 -Jelon0/lat0[/horizon]/scale (Azimuthal Equidistant)
77 -Jflon0/lat0[/horizon]/scale (Gnomonic)
78 -Jglon0/lat0[/horizon]/scale (Orthographic)
79 -Jglon0/lat0/altitude/azimuth/tilt/twist/Width/Height/scale
80 (General Perspective).
81 -Jslon0/lat0[/horizon][/slat]/scale (General Stereographic)
82 MISCELLANEOUS PROJECTIONS:
84 -Jh[lon0/]scale (Hammer)
86 -Ji[lon0/]scale (Sinusoidal)
87 -Jkf[lon0/]scale (Eckert IV)
88 -Jk[s][lon0/]scale (Eckert IV)
89 -Jn[lon0/]scale (Robinson)
90 -Jr[lon0/]scale (Winkel Tripel)
91 -Jv[lon0/]scale (Van der Grinten)
92 -Jw[lon0/]scale (Mollweide)
93 NON-GEOGRAPHICAL PROJECTIONS:
95 -Jp[a]scale[/origin][r|z] (Polar coordinates (theta,r))
97 -Jxx-scale[d|l|ppow|t|T][/y-scale[d|l|ppow|t|T]] (Linear, log,
98 and power scaling)
99 -R west, east, south, and north specify the Region of interest, and
101 you may specify them in decimal degrees or in
102 [+-]dd:mm[:ss.xxx][W|E|S|N] format. Append r if lower left and
103 upper right map coordinates are given instead of w/e/s/n. The
104 two shorthands -Rg and -Rd stand for global domain (0/360 and
105 -180/+180 in longitude respectively, with -90/+90 in latitude).
106 -D gives the deviation in X units of the plot for 1.0 on the scaled
108 trace.
109 -F[rgb|gray]
111 Fill trace (variable area, defaults to filling positive). rgb or
112 gray gives the color with which the imagemask is filled.
113 -W Draw wiggle trace.
115 You must specify at least one of -W and -F.
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119 No space between the option flag and the associated arguments.
120 -B Bias to apply to data (added to sample values).
122 -C Sample value at which to clip data (clipping is applied to both
124 positive and negative values).
125 -E Allow error difference between requested and actual trace loca‐
127 tions when using -T option.
128 -I Fill negative rather than positive excursions.
130 -K More PostScript code will be appended later [Default terminates
132 the plot system].
133 -L Override number of samples per trace in reel header (program
135 attempts to determine number of samples from each trace header
136 if possible to allow for variable length traces).
137 -M Override number of traces specified in reel header. Program
139 detects end of file (relatively) gracefully, but this parameter
140 limits number of traces that the program attempts to read.
141 -N Normalize trace by dividing by rms amplitude over full trace
143 length.
144 -O Selects Overlay plot mode [Default initializes a new plot sys‐
146 tem].
147 -P Selects Portrait plotting mode [Default is Landscape, see gmtde‐
149 faults to change this].
150 -S Read trace locations from trace headers: header is either c for
152 CDP, o for offset, or b<num> to read a long starting at byte
153 <num> in the header (first byte corresponds to num=0). Default
154 has location given by trace number.
155 -T Plot only traces whose location corresponds to a list given in
157 filename. Order in which traces are listed is not significant -
158 the entire space is checked for each trace.
159 -U Apply reduction velocity by shifting traces upwards by red‐
161 vel/|offset|. Negative velocity removes existing reduction.
162 Units should be consistent with offset in trace header and sam‐
163 ple interval.
164 -V Selects verbose mode, which will send progress reports to stderr
166 [Default runs "silently"].
167 -X Multiply trace locations by scale before plotting.
169 -Y Override sample interval in reel header.
171 -Z Do not plot traces with zero rms amplitude.
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175 To plot the SEGY file wa1.segy with normalized traces plotted at true
176 offset locations, clipped at +-3 and with wiggle trace and positive
177 variable area shading in black, use
178 pssegy wa1.segy -JX5/-5 -R0/100/0/10 -D1 -C3 -N -So -W -Fblack >
180 segy.ps
181 To plot the SEGY file wa1.segy with traces plotted at true cdp*0.1,
183 clipped at +-3, with bias -1 and negative variable area shaded red, use
184 pssegy wa1.segy -JX5/-5 -R0/100/0/10 -D1 -C3 -Sc -X0.1 -Fred -B-1 -I >
186 segy.ps
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189 GMT(1), pssegyz(1)
190GMT 4.3.1 15 May 2008 PSSEGY(1)