NAME
grdreformat - Converting between different grdfile formats.
SYNOPSIS
grdreformat ingrdfile[=id[/scale/offset[/nanvalue]]]
outgrdfile[=id[/scale/offset[/nanvalue]]] [
-Rwest/east/south/north[r] ] [ -V ]
DESCRIPTION
grdreformat reads a grdfile in one format and writes it out
using another format. As an option the user may select a
subset of the data to be written and to specify scaling,
translation, and nan-value.
ingrdfile
The grdfile to be read. Append format =id number if
not a standard GMT netcdf-based grdfile. If id is set,
you may optionally append scale and offset to scale the
data and then add an offset. If scale and offset are
supplied you may also append a value that represent
'not-a-number' (for floating-point grids this is unnec-
cesary since the IEEE NaN is used; however short
integers need a value which means no data available.)
outgrdfile
The grdfile to be written. Append format =id number if
not a standard GMT netcdf-based grdfile. If id is set,
you may optionally append scale and offset to scale the
data and then add an offset. If scale and offset are
supplied you may also append a value that represent
'not-a-number' (for floating-point grids this is unnec-
cesary since the IEEE NaN is used; however short
integers need a value which means no data available.)
OPTIONS
-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.
-V Selects verbose mode, which will send progress reports
to stderr [Default runs "silently"].
EXAMPLES
To create a 4-byte raw floating point grid from the netcdf
file data.grd, try
grdreformat data.grd ras_data.b4=1 -V
To make a 2-byte short integer file, scale it by 10, sub-
tract 32000, setting NaNs to -9999, do
grdreformat values.grd shorts.i2=2/10/-32000/-9999 -V
To create a Sun standard 8-bit rasterfile for a subset of
the data file image.grd, assuming the range in image.grd is
0-1 and we need 0-255, try
grdreformat image.grd -R-60/-40/-40/-30 image.ras8=3/255/0
-V
SEE ALSO
gmt(l), grdmath(l)