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


      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 ] [ -V ] [ -Z[flags] ] [ -: ] [ -bi[s][n] ]


      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.)

           ASCII [or binary] file holding z or (x,y,z) values.  xyz triplets
           do not have to be sorted (for binary triplets, 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.


      -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 registration].

      -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.

      -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 element 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  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.


      To create a grdfile from the ASCII data in, try

      xyz2grd -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


      gmt, grd2xyz, grdedit

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