1.. index:: ! segyz 2.. include:: ../module_supplements_purpose.rst_ 3 4******* 5segyz 6******* 7 8|segyz_purpose| 9 10Synopsis 11-------- 12 13.. include:: ../../common_SYN_OPTs.rst_ 14 15**gmt segyz** *SEGYfile* |-J|\ *parameters* 16|-J|\ **z**\|\ **Z**\ *parameters* 17|SYN_OPT-Rz| 18|-D|\ *deviation* |-F|\ [*color*] **-W** 19[ |-C|\ *clip* ] 20[ |-I| ] [ |-L|\ *nsamp* ] 21[ |-M|\ *ntrace* ] 22[ |-N| ] 23[ |-Q|\ *<mode><value>* ] 24[ |-S|\ *header_x*/*header_y* ] 25[ |SYN_OPT-U| ] 26[ |SYN_OPT-V| ] 27[ |SYN_OPT-X| ] 28[ |SYN_OPT-Y| ] 29[ |-Z| ] 30[ |SYN_OPT-p| ] 31[ |SYN_OPT-t| ] 32[ |SYN_OPT--| ] 33 34.. module_common_begins 35 36Description 37----------- 38 39Reads a native (IEEE) format SEGY file and produces a 40plot of the seismic data. The *imagemask* operator is used 41so that the seismic data are plotted as a 1-bit deep bitmap in a single 42(user-specified) color or gray shade, with a transparent background. The 43bitmap resolution is taken from the current GMT defaults. The 44seismic traces may be plotted at their true locations using information 45in the trace headers (in which case order of the traces in the file is 46not significant). Standard GMT geometry routines are used so that in 47principle any map projection may be used, however it is likely that the 48geographic projections will lead to unexpected results. Beware that a 49couple of the options for the 2-D plotter are not available in here. 50 51Note that the order of operations before the seismic data are plotted is 52deviation\*[clip]([bias]+[normalize](sample value)). Deviation 53determines how far *in the plot coordinates* a 54[normalized][biased][clipped] sample value of 1 plots from the trace 55location. 56 57The SEGY file should be a disk image of the tape format (i.e., 3200 byte 58text header, which is ignored, 400 byte binary reel header, and 240 byte 59header for each trace) with samples as native real\*4 (IEEE real on all 60the platforms to which I have access). 61 62Required Arguments 63------------------ 64 65*SEGYfile* 66 Seismic SEGY data set to be imaged. 67 68.. |Add_-J| replace:: |Add_-J_links| 69.. include:: /explain_-J.rst_ 70 :start-after: **Syntax** 71 :end-before: **Description** 72 73.. _-R: 74 75.. |Add_-Rgeo| unicode:: 0x20 .. just an invisible code 76.. include:: ../../explain_-Rgeo.rst_ 77 78.. _-D: 79 80**-D**\ *deviation* 81 gives the deviation in X units of the plot for 1.0 on the scaled 82 trace, This may be a single number (applied equally in X and Y 83 directions) or the pair *devX*\ /*devY*. 84 85.. _-F: 86 87**-F**\ [*color*] 88 Fill trace (variable area, defaults to filling positive). Specify the 89 *color* with which the imagemask is filled. 90 91.. _-W: 92 93**-W** 94 Draw wiggle trace. 95 96You *must* specify at least one of **-W** and **-F**. 97 98Optional Arguments 99------------------ 100 101.. _-A: 102 103**-A** 104 Flip the default byte-swap state (default assumes data have a 105 bigendian byte-order). 106 107.. _-C: 108 109**-C**\ *clip* 110 Sample value at which to clip data (clipping is applied to both 111 positive and negative values). 112 113.. _-I: 114 115**-I** 116 Fill negative rather than positive excursions. 117 118.. _-L: 119 120**-L**\ *nsamp* 121 Override number of samples per trace in reel header (program 122 attempts to determine number of samples from each trace header if 123 possible to allow for variable length traces). 124 125.. _-M: 126 127**-M**\ *ntrace* 128 Override number of traces specified in reel header. Program detects 129 end of file (relatively) gracefully, but this parameter limits 130 number of traces that the program attempts to read. 131 132.. _-N: 133 134**-N** 135 Normalize trace by dividing by rms amplitude over full trace length. 136 137.. _-Q: 138 139**-Q**\ *<mode><value>* 140 Can be used to change 5 different settings depending on *mode*: 141 **-Qb**\ *bias* to bias scaled traces (-Qb-0.1 subtracts 0.1 from values). 142 143 **-Qi**\ *dpi* sets the dots-per-inch resolution of the image [300]. 144 145 **-Qu**\ *redvel* to apply reduction velocity (negative removes reduction already present). 146 147 **-Qx**\ *mult* to multiply trace locations by *mult*. 148 149 **-Qy**\ *dy* to override sample interval in reel header. 150 151.. _-S: 152 153**-S**\ *header_x*/*header_y* 154 Read trace locations from trace headers: headers is either **c** for CDP, 155 **o** for offset, **b**\ *num* to read a long starting at byte *num* in the 156 header (first byte corresponds to num=0), or a number to fix the 157 location. First parameter for x, second for y. Default has X and Y 158 given by trace number. 159 160.. |Add_-U| replace:: |Add_-U_links| 161.. include:: ../../explain_-U.rst_ 162 :start-after: **Syntax** 163 :end-before: **Description** 164 165.. |Add_-V| replace:: |Add_-V_links| 166.. include:: /explain_-V.rst_ 167 :start-after: **Syntax** 168 :end-before: **Description** 169 170.. |Add_-XY| replace:: |Add_-XY_links| 171.. include:: ../../explain_-XY.rst_ 172 :start-after: **Syntax** 173 :end-before: **Description** 174 175.. _-Z: 176 177**-Z** 178 Do not plot traces with zero rms amplitude. 179 180.. |Add_perspective| unicode:: 0x20 .. just an invisible code 181.. include:: ../../explain_perspective.rst_ 182 183.. include:: ../../explain_-t.rst_ 184.. include:: ../../explain_help.rst_ 185 186.. module_common_ends 187 188Examples 189-------- 190 191.. include:: ../../oneliner_info.rst_ 192 193To plot the SEGY file wa1.segy with normalized traces plotted at true 194offset locations, clipped at ±3 and with wiggle trace and positive 195variable area shading in black, use 196 197 :: 198 199 gmt segyz wa1.segy -JX5i/-5i -D1 -Jz0.05i -E180/5 -R0/100/0/10/0/10 \ 200 -C3 -N -So -W -Fblack -pdf segy 201 202.. module_note_begins 203 204Bugs 205---- 206 207Variable area involves filling four-sided figures of distressing 208generality. I *know* that some of the more complex degenerate cases are 209not dealt with correctly or at all; the incidence of such cases 210increases as viewing angles become more oblique, and particularly as the 211viewing elevation increases. Wiggle-trace plotting is not affected. 212 213.. module_note_ends 214 215See Also 216-------- 217 218:doc:`gmt </gmt>`, 219:doc:`segy`, 220:doc:`segy2grd` 221