Provided by: gmt_4.5.11-1build1_amd64 bug

NAME

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

SYNOPSIS

       xyz2grd xyzfile -Ggrdfile -Ixinc[unit][=|+][/yinc[unit][=|+]] -Rwest/east/south/north[r] [
       -A[n|z|u|l] ] [ -Dxname/yname/zname/scale/offset/title/remark ] [ -E[nodata] ] [  -F  ]  [
       -H[i][nrec]  ]  [  -Nnodata  ]  [  -S[zfile]  ]  [  -V  ]  [  -Z[flags]  ]  [  -:[i|o] ] [
       -bi[s|S|d|D[ncol]|c[var1/...]] ] [ -fcolinfo ]

DESCRIPTION

       xyz2grd reads a z or xyz table and creates a binary grid file.   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 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 grid file.  (See GRID FILE FORMAT below.)

       -I     x_inc [and optionally y_inc] is the  grid  spacing.  Optionally,  append  a  suffix
              modifier.   Geographical (degrees) coordinates: Append m to indicate arc minutes or
              c to indicate arc seconds.  If one of the units e, k, i, or n is appended  instead,
              the  increment  is  assumed  to  be  given  in meter, km, miles, or nautical miles,
              respectively, and will be converted to the  equivalent  degrees  longitude  at  the
              middle  latitude of the region (the conversion depends on ELLIPSOID).  If /y_inc is
              given but set to 0 it will be reset equal to x_inc; otherwise it will be  converted
              to  degrees latitude.  All coordinates: If = is appended then the corresponding max
              x (east) or y (north) may be slightly adjusted to fit exactly the  given  increment
              [by  default  the  increment  may  be  adjusted  slightly to fit the given domain].
              Finally, instead of giving an increment you may specify the number of nodes desired
              by appending + to the supplied integer argument; the increment is then recalculated
              from the number of nodes and the domain.  The resulting increment value depends  on
              whether  you  have  selected  a  gridline-registered  or pixel-registered grid; see
              Appendix B for details.  Note: if -Rgrdfile is used then grid spacing  has  already
              been initialized; use -I to override the values.

       -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[:ss.xxx][W|E|S|N] format.  Append r if lower left
              and upper right map coordinates are given instead of w/e/s/n.  The  two  shorthands
              -Rg and -Rd stand for global domain (0/360 and -180/+180 in longitude respectively,
              with -90/+90 in latitude).  Alternatively, specify the name  of  an  existing  grid
              file  and  the  -R  settings  (and grid spacing, if applicable) are copied from the
              grid.  For calendar  time  coordinates  you  may  either  give  (a)  relative  time
              (relative  to  the  selected  TIME_EPOCH and in the selected TIME_UNIT; append t to
              -JX|x), or (b) 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  exactly  as  indicated
              (however, input, output and plot formats are customizable; see gmtdefaults).

OPTIONS

       -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  xname, yname, zname, scale, offset, title, and remark.  To leave
              some of these values untouched, specify = as the value.   Alternatively,  to  allow
              "/"  to  be  part of one of the values, use any non-alphanumeric character (and not
              the equal sign) as separator by both starting and  ending  with  it.  For  example:
              -D:xname:yname:zname:scale:offset:title:remark:

       -E     Convert  an  ESRI ArcInfo ASCII interchange grid format file to a GMT grid.  Append
              nodata which is a data value that should be set to NaN in the grid [If we find  the
              optional 6th record in the file we will use it instead].  The values normally given
              by -R, -I, and -F are determined from the ESRI header instead.

       -F     Force  pixel  node  registration  [Default  is   gridline   registration].    (Node
              registrations are defined in GMT Cookbook Appendix B on grid file formats.)

       -H     Input  file(s) has header record(s).  If used, the default number of header records
              is N_HEADER_RECS.  Use -Hi if only input data should have header  records  [Default
              will  write  out header records if the input data have them]. Blank lines and lines
              starting with # are always skipped.  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  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):

                   A  ASCII representation of one or more floating point values per record

                   a  ASCII representation of a single item per record
                   c  signed 1-byte character
                   u  unsigned 1-byte character
                   h  short 2-byte integer
                   H  unsigned short 2-byte integer
                   i  4-byte integer
                   l  long (4- or 8-byte) integer [architecture-dependent!]
                   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.  The difference between A and a is that the  latter  can
              decode  both dateTclock and ddd:mm:ss[.xx] formats while the former is strictly for
              regular floating point values.

       -:     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  d  (double)].
              Uppercase  S or D will force byte-swapping.  Optionally, append ncol, the number of
              columns in your binary input file if it exceeds the columns needed by the  program.
              Or  append  c  if  the  input  file  is netCDF. Optionally, append var1/var2/... to
              specify the variables to be read.  [Default is 3 input columns].  This option  only
              applies to xyz input files; see -Z for z tables.

       -f     Special  formatting  of  input  and/or  output columns (time or geographical data).
              Specify i or o to make this apply only to  input  or  output  [Default  applies  to
              both].   Give one or more columns (or column ranges) separated by commas.  Append T
              (absolute calendar time), t (relative time in chosen TIME_UNIT since TIME_EPOCH), x
              (longitude),  y  (latitude),  or  f (floating point) to each column or column range
              item.  Shorthand -f[i|o]g means -f[i|o]0x,1y (geographic coordinates).

GRID VALUES PRECISION

       Regardless of the precision of the input data, GMT programs that create  grid  files  will
       internally  hold  the  grids  in  4-byte  floating point arrays.  This is done to conserve
       memory and furthermore most if not all real data can be stored using 4-byte floating point
       values.   Data  with  higher  precision  (i.e.,  double  precision  values) will lose that
       precision once GMT operates on the grid or  writes  out  new  grids.   To  limit  loss  of
       precision  when  processing  data you should always consider normalizing the data prior to
       processing.

GRID FILE FORMATS

       By default GMT writes out grid as single precision floats  in  a  COARDS-complaint  netCDF
       file  format.  However, GMT is able to produce grid files in many other commonly used grid
       file formats and also facilitates so called "packing" of grids, writing out floating point
       data as 2- or 4-byte integers. To specify the precision, scale and offset, the user should
       add the suffix =id[/scale/offset[/nan]], where id is a two-letter identifier of  the  grid
       type  and  precision,  and  scale  and  offset  are optional scale factor and offset to be
       applied to all grid values, and nan is the value  used  to  indicate  missing  data.   See
       grdreformat(1)  and  Section  4.17  of  the  GMT Technical Reference and Cookbook for more
       information.

       When writing a netCDF file, the grid is stored by default with the variable name  "z".  To
       specify  another  variable  name varname, append ?varname to the file name.  Note that you
       may need to escape the special meaning of ? in your shell program by putting  a  backslash
       in front of it, or by placing the filename and suffix between quotes or double quotes.

GEOGRAPHICAL AND TIME COORDINATES

       When  the  output  grid  type  is  netCDF,  the  coordinates  will be labeled "longitude",
       "latitude", or "time" based on the attributes of the input data or grid (if any) or on the
       -f  or  -R  options.  For  example,  both  -f0x -f1t and -R 90w/90e/0t/3t will result in a
       longitude/time grid. When the x, y, or z coordinate is time, it will be stored in the grid
       as  relative time since epoch as specified by TIME_UNIT and TIME_EPOCH in the .gmtdefaults
       file or on the command line.  In addition, the unit attribute of the  time  variable  will
       indicate both this unit and epoch.

EXAMPLES

       To create a grid file from the ASCII data in hawaii_grv.xyz, use

       xyz2grd  hawaii_grv.xyz  -D  degree/degree/mGal/1/0/"Hawaiian  Gravity"/"GRS-80  Ellipsoid
       used" -G hawaii_grv_new.grd -R 198/208/18/25 -I 5m -V

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

       xyz2grd raw.b -D m/m/m/1/0/=/= -G raw.grd -R 0/100/0/100 -I 1 -V -Z -b 3

       To  make  a  grid file 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), use

       xyz2grd topo30. -D m/m/m/1/0/=/= -G ustopo.grd -R 234/294/24/50 -I 30c -N-9999 -B -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 -S new_floats.bin -V -Zf

SEE ALSO

       GMT(1), grd2xyz(1), grdedit(1)