Provided by: gmt-common_5.4.5+dfsg-1_all bug


       segy2grd - Converting SEGY data to a GMT grid


       segy2grd segyfile  -Ggrdfile
        -Rregion                  [                   -A[n|z]                 ]                 [
       -D[+xxname][+yyname][+zzname][+sscale][+ooffset][+ninvalid][+ttitle][+rremark]     ]     [
       -L[nsamp]  ]  [   -M[ntraces]  ]  [   -Nnodata  ]  [   -Q<mode><value> ] [  -S[header] ] [
       -V[level] ] [ -bibinary ] [ -:[i|o] ]

       Note: No space is allowed between the option flag and the associated arguments.


       segy2grd reads an IEEE SEGY file and creates a binary grid file.  Either a simple  mapping
       (equivalent  to  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.


       segyfile  is  an  IEEE  floating  point  SEGY  file.  Traces are all assumed to start at 0

              grdfile is the name of the binary output grid file.

       -I     x_inc [and optionally y_inc] is the grid spacing. Append m to indicate minutes or s
              to indicate seconds.

              west,  east,  south,  and north specify the region of interest, and you may specify
              them in decimal degrees or in [±]dd:mm[][W|E|S|N] format Append +r if  lower
              left  and  upper  right  map  coordinates  are  given  instead  of w/e/s/n. The two
              shorthands -Rg and -Rd stand for global domain (0/360 and  -180/+180  in  longitude
              respectively,  with  -90/+90  in  latitude).  Alternatively for grid creation, give
              Rcodelon/lat/nx/ny, where code is a 2-character combination of L, C, R  (for  left,
              center,  or right) and T, M, B for top, middle, or bottom. e.g., BL for lower left.
              This indicates which point on a rectangular region the  lon/lat  coordinate  refers
              to,  and  the grid dimensions nx and ny with grid spacings via -I is used to create
              the corresponding region.  Alternatively, specify the name of an existing grid file
              and  the  -R  settings  (and grid spacing, if applicable) are copied from the grid.
              Appending +uunit expects projected (Cartesian) coordinates compatible  with  chosen
              -J and we inversely project to determine actual rectangular geographic region.  For
              perspective view (-p), optionally append /zmin/zmax.  In case of  perspective  view
              (-p),  a z-range (zmin, zmax) can be appended to indicate the third dimension. This
              needs to be done only when using the -Jz option, not when using only the -p option.
              In  the  latter  case  a  perspective  view  of the plane is plotted, with no third


              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.

              Give one or more combinations for values xname, yname, zname  (give  the  names  of
              those  variables  and  in square bracket their units, e.g., "distance [km]"), scale
              (to multiply grid values after read [normally 1]), offset (to  add  to  grid  after
              scaling  [normally  0]),  invalid  (a value to represent missing data [NaN]), title
              (anything you like), and remark (anything you like). Items not listed  will  remain
              untouched.   Give a blank name to completely reset a particular string.  Use quotes
              to group texts with more than one word.  Note that for geographic grids (-fg) xname
              and yname are set automatically.

       -L     Let nsamp override number of samples in each trace.

              Fix number of traces to read in. Default tries to read 10000 traces.  -M0 will read
              number in binary header, -Mntraces will attempt to read only n traces.

              No data. Set nodes with no input sample to this value [Default is NaN].


              Can be used to change two different settings depending on mode:
                     -Qxx-scale applies scalar x-scale to coordinates in trace  header  to  match
                     the coordinates specified in -R.

                     -Qys_int specifies sample interval as s_int if incorrect in the SEGY file.

              Set  variable  spacing;  header  is  c for cdp, o for offset, or bnumber 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.

       -V[level] (more ...)
              Select verbosity level [c].

       -r (more ...)
              Set pixel node registration [gridline].

       -^ or just -
              Print a short message about the syntax of the command, then exits (NOTE: on Windows
              just use -).

       -+ or just +
              Print  an  extensive  usage  (help)  message,  including  the  explanation  of  any
              module-specific option (but not the GMT common options), then exits.

       -? or no arguments
              Print  a  complete  usage (help) message, including the explanation of all options,
              then exits.


       To create a grid file from an even spaced SEGY file test.segy, try

              gmt segy2grd test.segy -I0.1/0.1 -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 -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


       gmt, grd2xyz, grdedit, pssegy, xyz2grd


       2019, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe