1PSSEGY(1) GMT PSSEGY(1)
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6 pssegy - Plot a SEGY file on a map
7
9 pssegy SEGYfile -Jparameters
10 -Rregion
11 -Ddeviation
12 -F[color] -W [ -Cclip ] [ -Eerror ] [ -I ] [ -K ] [ -Lnsamp ] [
13 -Mntrace ] [ -N ] [ -O ] [ -P ] [ -Q<mode><value> ] [ -Sheader ] [
14 -Tfilename ] [ -U[stamp] ] [ -V[level] ] [ -Xx_offset ] [ -Yy_off‐
15 set ] [ -pflags ] [ -ttransp ]
16 Note: No space is allowed between the option flag and the associated
18 arguments.
19
21 pssegy reads a native (IEEE) format SEGY file and produces a PostScript
22 image of the seismic data. The imagemask operator is used so that the
23 seismic data are plotted as a 1-bit deep bitmap in a single (user-spec‐
24 ified) color or gray shade, with a transparent background. The bitmap
25 resolution is taken from the current GMT defaults. The seismic traces
26 may be plotted at their true locations using information in the trace
27 headers (in which case order of the traces in the file is not signifi‐
28 cant). Standard GMT geometry routines are used so that in principle any
29 map projection may be used, however it is likely that the geographic
30 projections will lead to unexpected results. Beware also that some
31 parameters have non-standard meanings.
32 Note that the order of operations before the seismic data are plotted
34 is deviation*[clip]([bias]+[normalize](sample value)). Deviation deter‐
35 mines how far in the plot coordinates a [normalized][biased][clipped]
36 sample value of 1 plots from the trace location.
37 The SEGY file should be a disk image of the tape format (i.e., 3200
39 byte text header, which is ignored, 400 byte binary reel header, and
40 240 byte header for each trace) with samples as native real*4 (IEEE
41 real on all the platforms to which I have access).
42
44 SEGYfile
45 Seismic SEGY data set to be imaged.
46 -Jparameters (more ...)
48 Select map projection.
49 -Rwest/east/south/north[/zmin/zmax][+r][+uunit]
51 west, east, south, and north specify the region of interest, and
52 you may specify them in decimal degrees or in
53 [±]dd:mm[:ss.xxx][W|E|S|N] format Append +r if lower left and
54 upper right map coordinates are given instead of w/e/s/n. The
55 two shorthands -Rg and -Rd stand for global domain (0/360 and
56 -180/+180 in longitude respectively, with -90/+90 in latitude).
57 Alternatively for grid creation, give Rcodelon/lat/nx/ny, where
58 code is a 2-character combination of L, C, R (for left, center,
59 or right) and T, M, B for top, middle, or bottom. e.g., BL for
60 lower left. This indicates which point on a rectangular region
61 the lon/lat coordinate refers to, and the grid dimensions nx and
62 ny with grid spacings via -I is used to create the corresponding
63 region. Alternatively, specify the name of an existing grid
64 file and the -R settings (and grid spacing, if applicable) are
65 copied from the grid. Appending +uunit expects projected (Carte‐
66 sian) coordinates compatible with chosen -J and we inversely
67 project to determine actual rectangular geographic region. For
68 perspective view (-p), optionally append /zmin/zmax. In case of
69 perspective view (-p), a z-range (zmin, zmax) can be appended to
70 indicate the third dimension. This needs to be done only when
71 using the -Jz option, not when using only the -p option. In the
72 latter case a perspective view of the plane is plotted, with no
73 third dimension.
74 -Ddeviation
76 gives the deviation in X units of the plot for 1.0 on the scaled
77 trace.
78 -F[color]
80 Fill trace (variable area, defaults to filling positive). Spec‐
81 ify the color with which the imagemask is filled.
82 -W Draw wiggle trace.
84 You must specify at least one of -W and -F.
86
88 -A Flip the default byte-swap state (default assumes data have a
89 bigendian byte-order).
90 -Cclip Sample value at which to clip data (clipping is applied to both
92 positive and negative values).
93 -Eerror
95 Allow error difference between requested and actual trace loca‐
96 tions when using -T option.
97 -I Fill negative rather than positive excursions.
99 -K (more ...)
101 Do not finalize the PostScript plot.
102 -L Override number of samples per trace in reel header (program
104 attempts to determine number of samples from each trace header
105 if possible to allow for variable length traces).
106 -M Override number of traces specified in reel header. Program
108 detects end of file (relatively) gracefully, but this parameter
109 limits number of traces that the program attempts to read.
110 -N Normalize trace by dividing by rms amplitude over full trace
112 length.
113 -O (more ...)
115 Append to existing PostScript plot.
116 -P (more ...)
118 Select "Portrait" plot orientation.
119 -Q<mode><value>
121 Can be used to change 5 different settings depending on mode:
123 -Qbbias to bias scaled traces (-Qb-0.1 subtracts 0.1 from
124 values).
125 -Qidpi sets the dots-per-inch resolution of the image
127 [300].
128 -Quredvel to apply reduction velocity (negative value
130 removes reduction already present).
131 -Qxmult to multiply trace locations by mult.
133 -Qydy to override sample interval in SEGY reel header.
135 -Sheader
137 Read trace locations from trace headers: header is either c for
138 CDP, o for offset, or bnum to read a long starting at byte num
139 in the header (first byte corresponds to num = 0). Default has
140 location given by trace number.
141 -Tfilename
143 Plot only traces whose location corresponds to a list given in
144 filename. Order in which traces are listed is not significant -
145 the entire space is checked for each trace.
146 -U[[just]/dx/dy/][c|label] (more ...)
148 Draw GMT time stamp logo on plot.
149 -V[level] (more ...)
151 Select verbosity level [c].
152 -X[a|c|f|r][x-shift[u]]
154 -Y[a|c|f|r][y-shift[u]] (more ...)
156 Shift plot origin.
157 -Z Do not plot traces with zero rms amplitude.
159 -p[x|y|z]azim[/elev[/zlevel]][+wlon0/lat0[/z0]][+vx0/y0] (more ...)
161 Select perspective view.
162 -t[transp] (more ...)
164 Set PDF transparency level in percent.
165 -^ or just -
167 Print a short message about the syntax of the command, then
168 exits (NOTE: on Windows just use -).
169 -+ or just +
171 Print an extensive usage (help) message, including the explana‐
172 tion of any module-specific option (but not the GMT common
173 options), then exits.
174 -? or no arguments
176 Print a complete usage (help) message, including the explanation
177 of all options, then exits.
178
180 To plot the SEGY file wa1.segy with normalized traces plotted at true
181 offset locations, clipped at +-3 and with wiggle trace and positive
182 variable area shading in black, use
183 gmt pssegy wa1.segy -JX5i/-5i -R0/100/0/10 -D1 -C3 -N -So -W -Fblack > segy.ps
185 To plot the SEGY file wa1.segy with traces plotted at true cdp*0.1,
187 clipped at +/-3, with bias -1 and negative variable area shaded red,
188 use
189 gmt pssegy wa1.segy -JX5i/-5i -R0/100/0/10 -D1 -C3 -Sc -Qx0.1 -Fred -Qb-1 -I > segy.ps
191
193 gmt, pssegyz, segy2grd
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196 2019, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe
1975.4.5 Feb 24, 2019 PSSEGY(1)