NAME

       segy2grd - Converting SEGY file to grid file format

SYNOPSIS

       segy2grd segyfile -Ggrdfile -Ixinc[unit][=|+][/yinc[unit][=|+]] -Rwest/east/south/north[r]
       [ -A[n|z] ] [ -Dxname/yname/zname/scale/offset/title/remark ] [ -F  ]    [  -Nnodata  ]  [
       -S[zfile] ] [ -V ] [ -Z[flags] ] [ -:[i|o] ] [ -bi[s|S|d|D[ncol]|c[var1/...]] ]

DESCRIPTION

       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
       time/depth.

       -G     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 c
              to indicate seconds.

       -R     west, east, south, and north specify the Region of interest, and  you  may  specify
              them  in  decimal  degrees  or  in [+-]dd:mm[:ss.xxx][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,  specify  the  name  of  an
              existing grid file and the -R settings (and grid spacing, if applicable) are copied
              from the grid.

OPTIONS

       -A     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     Give values for xname, yname, zname, scale, offset, title, and  remark.   To  leave
              some of these values untouched, specify = as the value.

       -F     Force pixel registration [Default is grid registration].

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

       -S     set  variable spacing header is c for cdp, o for offset, b<number> for 4-byte float
              starting at byte number If -S not set, assumes even spacing of samples at  the  dx,
              dy supplied with -I

       -L     Override number of samples in each trace

       -X     applies  scalar  x-scale  to  coordinates  in trace header to match the coordinates
              specified in -R

       -Y     Specifies sample interval as s_int if incorrect in the SEGY file

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

       -V     Selects  verbose  mode,  which  will  send progress reports to stderr [Default runs
              "silently"].

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

              segy2grd test.segy -I 0.1/0.1 -G test.grd -R 198/208/18/25 -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

              segy2grd test.segy  -G test.grd -R 0/100/0/10 -I 0.5/0.2 -V -X 0.1  -Y 0.1

              Because the grid interval is larger than the SEGY  file  sampling,  the  individual
              samples will be averaged in bins

SEE ALSO

       GMT(1), grd2xyz(1), grdedit(1), pssegy(1)