SEGY2GRD(1gmt)						       Generic Mapping Tools						    SEGY2GRD(1gmt)

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/off-
       set/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). Alterna-
	      tively, 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 -I0.1/0.1 -Gtest.grd -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

	      segy2grd test.segy  -Gtest.grd -R0/100/0/10 -I0.5/0.2 -V -X0.1  -Y0.1

	      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)

GMT 4.5.7							    15 Jul 2011 						    SEGY2GRD(1gmt)