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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]
] [ -Dxunit/yunit/zunit/scale/offset/title/remark ] [ -F ] [ -H[nrec] ] [
-L ] [ -Nnodata ] [ -S[zfile] ] [ -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.)
- [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 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.
- -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. [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 .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 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
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)].
Applies to geographic coordinates only.
- -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 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
gmt(3)
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