xyz2grd
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] [ -A[n|z] ] [ -Dxu
nit/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 grd
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 orga
nized 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 sec
onds.
-R west, east, south, and north specify the Region of
interest. To specify boundaries in degrees and min
utes [and seconds], use the dd:mm[:ss] format.
Append r if lower left and upper right map coordi
nates are given instead of wesn.
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.
[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 registra
tion].
defaults 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 [multi
ples of] 360 degrees [Default assumes no periodic
ity].
-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 con
tained 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 for
mats: 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 num
ber of bytes (probably a header). If the byte-order
needs to be swapped, append w. Select one of sev
eral 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.
tude,longitude) input/output. [Default is (longi
tude,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.
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)
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