NAME

     xyz2grd - Converting an ASCII or binary table  to  grd  file
     format


SYNOPSIS

     xyz2grd    xyzfile    -Ggrdfile    -Ix_inc[m|c][/y_inc[m|c]]
     -Rwest/east/south/north[r]                                 [
     -Dxunit/yunit/zunit/scale/offset/title/remark ]  [  -F  ]  [
     -H[nrec]  ]  [  -L  ]  [  -Nnodata  ] [ -S[zfile] ] [ -V ] [
     -Z[flags] ] [ -: ] [ -bi[s][n] ]


DESCRIPTION

     xyz2grd reads a z or xyz table and creates a binary grdfile.
     xyz2grd  will  report if some of the nodes are not filled in
     with data.  Such unconstrained nodes  are  set  to  a  value
     specified  by  the  user  [Default is NaN].  Nodes with more
     than one value will be set to  the  average  value.   As  an
     option  (using  -Z), a 1-column z-table may be read assuming
     all nodes are present (z-tables can be  in  organized  in  a
     number of formats, see -Z below.)

     [xy]zfile
          ASCII [or binary] file holding  z  or  (x,y,z)  values.
          xyz  triplets do not have to be sorted (for binary tri-
          plets, see -b).  1-column z tables must be  sorted  and
          the -Z must be set).

     -G   grdfile is the name of the binary output grdfile.

     -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.  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.


OPTIONS

     -D   Give values for xunit,  yunit,  zunit,  scale,  offset,
          title,  and  remark.   To  leave  some  of these values
          untouched, specify = as the value.

     -F   Force pixel registration  [Default  is  grid  registra-
          tion].

     -H   Input file(s) has Header record(s).  Number  of  header
          records  can  be  changed  by editing your .gmtdefaults
          file.  If used, GMT default is 1  header  record.   Not
          used with binary data.

     -L   Indicates that the x column contains longitudes,  which
          may differ from the regions in -R by [multiples of] 360
          degrees [Default assumes no periodicity].

     -N   No data.  Set nodes with no input xyz triplet  to  this
          value  [Default  is NaN].  For z-tables, this option is
          used to replace z-values that equal nodata with NaN.

     -S   Swap the byte-order of the input only.  No grid file is
          produced.   You  must  also  supply the -Z option.  The
          output is written to zfile (or stdout if not supplied).

     -V   Selects verbose mode, which will send progress  reports
          to stderr [Default runs "silently"].

     -Z   Read a 1-column ASCII [or binary] table.  This  assumes
          that  all the nodes are present and sorted according to
          specified ordering convention contained in  flags.   If
          incoming  data  represents  rows, make flags start with
          T(op) if first row is y = ymax or B(ottom) if first row
          is  y  =  ymin.   Then,  append L or R to indicate that
          first element is at left or right end of row.  Likewise
          for column formats: start with L or R to position first
          column, and then append T or B to position  first  ele-
          ment  in a row. For gridline registered grids:  If data
          are periodic in x but the incoming data do not  contain
          the (redundant) column at x = xmax, append x.  For data
          periodic in y without redundant row at y = ymax, append
          y.   Append  sn  to  skip  the  first n number of bytes
          (probably a header).  If the  byte-order  needs  to  be
          swapped,  append  w.   Select one of several data types
          (all binary except a):

               a  ASCII representation
               c  signed 1-byte character
               u  unsigned 1-byte character
               h  short 2-byte integer
               i  4-byte integer
               l  long (4- or 8-byte) integer
               f  4-byte floating point single precision
               d  8-byte floating point double precision

          Default  format  is  scanline  orientation   of   ASCII
          numbers:  -ZTLa.  Note that -Z only applies to 1-column
          input.

     -:   Toggles      between      (longitude,latitude)      and
          (latitude,longitude)    input/output.     [Default   is
          (longitude,latitude)].

     -bi  Selects binary input.  Append s  for  single  precision
          [Default  is  double].   Append  n  for  the  number of
          columns in the binary file(s).   [Default  is  3  input
          columns].  This option only applies to xyz input files;
          see -Z for z tables.


EXAMPLES

     To create a grdfile from the ASCII data  in  hawaii_grv.xyz,
     try

     xyz2grd  hawaii_grv.xyz   -Ddegree/degree/mGal/1/0/"Hawaiian
     Gravity"/"GRS-80    Ellipsoid   used"   -Ghawaii_grv_new.grd
     -R198/208/18/25 -I5m -V

     To create a grdfile from the raw binary  (3-column,  single-
     precision) scanline-oriented data raw.b, try

     xyz2grd raw.b -Dm/m/m/1/0/=/= -Graw.grd -R0/100/0/100 -I1 -V
     -Z -b3

     To make a grdfile  from  the  raw  binary  USGS  DEM  (short
     integer)  scanline-oriented  data topo30. on the NGDC global
     relief Data CD-ROM, with values of  -9999  indicate  missing
     data,  one  must on some machine reverse the byte-order.  On
     such machines (like Sun), try

     xyz2grd topo30. -Dm/m/m/1/0/=/= -Gustopo.grd -R234/294/24/50
     -I30c -N-9999 -V -ZTLhw

     Say you have received a binary  file  with  4-byte  floating
     points  that  were  written  on a machine of different byte-
     order than yours.  You can swap the byte-order with

     xyz2grd floats.bin -Snew_floats.bin -V -Zf


SEE ALSO

     gmt(l), grd2xyz(l), grdedit(l)