grdedit - Modifying the header in a 2-D grdfile
grdedit grdfile [ -A ] [ -Dxunit/yunit/zunit/scale/offset/title/remark
] [ -Rwest/east/south/north[r] ] [ -S ]
grdedit reads the header information in a binary 2-D grdfile and
replaces the information with values provided on the command line [if
any]. As an option, global, geographical grids (with 360 degrees
longitude range) can be rotated in the east-west direction. grdedit
only operates on files containing a grdheader.
No space between the option flag and the associated arguments.
Use upper case for the option flags and lower case for modifiers.
Name of the 2-D grdfile to modify
-A If necessary, adjust the file's x_inc, y_inc to be compatible
with its domain (or a new domain set with -R). Older gridfiles
(i.e., created prior to GMT 3.1) often had excessive slop in
x_inc, y_inc and an adjustment is necessary. Newer files are
-D Give new values for xunit, yunit, zunit, scale, offset, title,
and remark. To leave some of the values untouched, specify = as
the new value.
-R west, east, south, and north specify the Region of interest. To
specify boundaries in degrees and minutes [and seconds], use the
dd:mm[:ss] format. Append r if lower left and upper right map
coordinates are given instead of wesn.
-S For global, geographical grids only. Grid values will be shifted
laterally according to the new borders given in -R.
Let us assume the file data.grd covers the area 300/310/10/30. We
want to change the boundaries from geodetic longitudes to geographic
and put a new title in the header. We accomplish this by
grdedit data.grd -R-60/-50/10/30 -D=/=/=/=/=/"Gravity Anomalies"/=
The grid world.grd has the limits 0/360/-72/72. To shift the data so
that the limits would be -180/180/-72/72, use
grdedit world.grd -R-180/180/-72/72 -S
The file junk.grd was created prior to GMT 3.1 with incompatible -R
and -I arguments. To reset the x- and y-increments we run
grdedit junk.grd -A
gmt, grd2xyz, xyz2grd
Man(1) output converted with