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]     [     -A[n|z|u|l]     ]     [      -Dxu-
       nit/yunit/zunit/scale/offset/title/remark ] [ -F ] [ -H[nrec] ] [ -Nno-
       data ] [ -S[zfile] ] [ -V ] [ -Z[flags] ]  [  -:  ]  [  -bi[s][n]  ]  [
       -f[i|o]colinfo ]


       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 for-
       mats, 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     xmin, xmax, ymin, and ymax specify the Region of  interest.  For
              geographic  regions,  these  limits  correspond  to  west, east,
              south, and north and you may specify them in decimal degrees  or
              in  [+-]dd:mm[][W|E|S|N]  format.  Append r if lower left
              and upper right map coordinates are given instead of  wesn.  The
              two  shorthands  -Rg  -Rd  stand  for  global  domain  (0/360 or
              -180/+180 in longitude respectively, with -90/+90 in  latitude).
              For  calendar time coordinates you may either give relative time
              (relative  to  the  selected  TIME_EPOCH  and  in  the  selected
              TIME_UNIT;  append  t  to  -JX|x),  or absolute time of the form
              [date]T[clock] (append T to -JX|x). At least  one  of  date  and
              clock must be present; the T is always required. The date string
              must be of the form [-]yyyy[-mm[-dd]]  (Gregorian  calendar)  or
              yyyy[-Www[-d]]  (ISO week calendar), while the clock string must
              be of the form hh:mm:ss[.xxx]. The use of delimiters  and  their
              type  and  positions must be as indicated (however, input/output
              and plotting formats are flexible).


       -A     Add up multiple values that belong to the  same  node  (same  as
              -Az).   Append  n to simply count the number of data points that
              were assigned to each node.  Append l or u to  find  the  lowest
              (minimum)  or  upper (maximum) value at each node, respectively.
              [Default (no -A option) will calculate mean value].  Ignored  if
              -Z is given.

       -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  .gmtdefaults4  file.  If  used,  GMT
              default  is  1  header record. Use -Hi if only input data should
              have header records [Default will write out  header  records  if
              the input data have them].  Not used with binary data.

       -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  indi-
              cate 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 and/or output. [Default is (longitude,latitude)].   Append
              i  to  select  input  only  or o to select output only. [Default
              affects both].

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

       -f     Special  formatting  of  input  and output columns (time or geo-
              graphical data) Specify i(nput) or  o(utput)  [Default  is  both
              input  and output].  Give one or more columns (or column ranges)
              separated by commas.  Append T (Absolute calendar time), t (time
              relative  to  chosen TIME_EPOCH), x (longitude), y (latitude), g
              (geographic coordinate), or f (floating point) to each column or
              column range item.


       To create a grdfile from the ASCII data in, use

       xyz2grd    -Ddegree/degree/mGal/1/0/"Hawaiian   Grav-
       ity"/"GRS-80 Ellipsoid used" -Ghawaii_grv_new.grd -R198/208/18/25  -I5m

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

       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)  scan-
       line-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), use

       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


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

GMT4.0                            1 Oct 2004                        XYZ2GRD(l)

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