.. index:: ! segy2grd .. include:: ../module_supplements_purpose.rst_ ******** segy2grd ******** |segy2grd_purpose| Synopsis -------- .. include:: ../../common_SYN_OPTs.rst_ **gmt segy2grd** *segyfile* |-G|\ *grdfile* |SYN_OPT-I| |SYN_OPT-R| [ |-A|\ [**n**\|\ **z**] ] [ |-D|\ |SYN_OPT-D2| ] [ |-L|\ [*nsamp*] ] [ |-M|\ [*ntraces*] ] [ |-Q|\ **x**\|\ **y**\ *value* ] [ |-S|\ [*header*] ] [ |SYN_OPT-V| ] [ |SYN_OPT-bi| ] [ |SYN_OPT-di| ] [ |SYN_OPT-:| ] [ |SYN_OPT--| ] |No-spaces| Description ----------- **segy2grd** reads an IEEE SEGY file and creates a binary grid file. Either a simple mapping (equivalent to :doc:`xyz2grd ` -Z) or a more complicated averaging where a particular grid cell includes values from more than one sample in the SEGY file can be done. **segy2grd** will report if some of the nodes are not filled in with data. Such unconstrained nodes are set to a value specified by the user [Default is NaN]. Nodes with more than one value will be set to the average value. Required Arguments ------------------ *segyfile* is an IEEE floating point SEGY file. Traces are all assumed to start at 0 time/depth. .. _-G: .. |Add_outgrid| replace:: Give the name of the output grid file. .. include:: /explain_grd_inout.rst_ :start-after: outgrid-syntax-begins :end-before: outgrid-syntax-ends .. _-I: **-I** *x_inc* [and optionally *y_inc*] is the grid spacing. Append **m** to indicate minutes or **s** to indicate seconds. .. _-R: .. |Add_-Rgeo| unicode:: 0x20 .. just an invisible code .. include:: ../../explain_-Rgeo.rst_ Optional Arguments ------------------ .. _-A: **-A**\ [**n**\|\ **z**] Add up multiple values that belong to the same node (same as **-Az**). Append **n** to simply count the number of data points that were assigned to each node. [Default (no |-A| option) will calculate mean value]. Not used for simple mapping. .. _-D: .. include:: ../../explain_-D_cap.rst_ .. _-L: **-L** Let *nsamp* override number of samples in each trace. .. _-M: **-M**\ [*ntraces*] Fix number of traces to read in. Default tries to read 10000 traces. **-M**\ 0 will read number in binary header, **-M**\ *ntraces* will attempt to read only *n* traces. .. _-Q: **-Q**\ **x**\|\ **y**\ *value* Can be used to change two different settings depending on the directive: **-Qx**\ *x-scale* applies scalar *x-scale* to coordinates in trace header to match the coordinates specified in |-R|. **-Qy**\ *s_int* specifies sample interval as *s_int* if incorrect in the SEGY file. Repeatable. .. _-S: **-S**\ [*header*] Set variable spacing; *header* is **c** for cdp, **o** for offset, or **b**\ *number* for 4-byte float starting at byte *number*. If |-S| not set, assumes even spacing of samples at the *x_inc, y_inc* supplied with |-I|. .. |Add_-V| replace:: |Add_-V_links| .. include:: /explain_-V.rst_ :start-after: **Syntax** :end-before: **Description** .. |Add_-di| replace:: Also sets nodes with no input SEGY coverage to this value [Default is NaN]. .. include:: ../../explain_-di.rst_ .. |Add_nodereg| unicode:: 0x20 .. just an invisible code .. include:: ../../explain_nodereg.rst_ .. include:: ../../explain_help.rst_ Examples -------- To create a grid file from an even spaced SEGY file test.segy, try:: gmt segy2grd test.segy -I0.1/0.1 -Gtest.nc -R198/208/18/25 -V Note that this will read in 18-25s (or km) on each trace, but the first trace will be assumed to be at X=198 To create a grid file from the SEGY file test.segy, locating traces according to the CDP number, where there are 10 CDPs per km and the sample interval is 0.1, try:: gmt segy2grd test.segy -Gtest.nc -R0/100/0/10 -I0.5/0.2 -V -Qx0.1 -Qy0.1 Because the grid interval is larger than the SEGY file sampling, the individual samples will be averaged in bins See Also -------- :doc:`gmt `, :doc:`grd2xyz `, :doc:`grdedit `, :doc:`segy`, :doc:`xyz2grd `