segyfile is an IEEE floating point SEGY file. Traces are all assumed to start at 0 time/depth.
|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.|
-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"].
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
|GMT 4.5.14||SEGY2GRD (1)||1 Nov 2015|