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)