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 unneccesary 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 unneccesary since the IEEE NaN is used; however short integers need a
              value  which  means no data available.)  For format =id > 0 the size of the GMT grdheader block is
              hsize = 896 bytes, and the total size of the file is hsize + nx * ny * item_size, where  item_size
              is  the  size in bytes of each element (1, 2, 4). Bit grids are stored using 4-byte integers, each
              holding 32 bits, so for these files the size equation is modified by using ceil  (nx  /  32)  *  4
              instead of nx. For header and grid details, see Appendix B.

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, subtract 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(1gmt), grdmath(1gmt)

                                                   1 Jan 2004                                     GRDREFORMAT(l)