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.TH "XYZ2GRD" "1gmt" "Jan 10, 2019" "5.4.5" "GMT"
.SH NAME
xyz2grd \- Convert data table to a grid file
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.SH SYNOPSIS
.sp
\fBxyz2grd\fP [ \fItable\fP ]  \fB\-G\fP\fIgrdfile\fP
 \fB\-I\fP\fIincrement\fP
 \fB\-R\fP\fIregion\fP
[  \fB\-A\fP[\fBd\fP|\fBf\fP|\fBl\fP|\fBm\fP|\fBn\fP|\fBr\fP|\fBS\fP|\fBs\fP|\fBu\fP|\fBz\fP] ]
[  \fB\-D\fP[\fB+x\fP\fIxname\fP][\fB+y\fP\fIyname\fP][\fB+z\fP\fIzname\fP][\fB+s\fP\fIscale\fP][\fB+o\fP\fIoffset\fP][\fB+n\fP\fIinvalid\fP][\fB+t\fP\fItitle\fP][\fB+r\fP\fIremark\fP] ]
[  \fB\-J\fP\fIparameters\fP ]
[  \fB\-S\fP[\fIzfile\fP] ]
[  \fB\-V\fP[\fIlevel\fP] ]
[  \fB\-Z\fP[\fIflags\fP] ]
[ \fB\-bi\fPbinary ]
[ \fB\-di\fPnodata ]
[ \fB\-e\fPregexp ]
[ \fB\-f\fPflags ]
[ \fB\-h\fPheaders ]
[ \fB\-i\fPflags ]
[ \fB\-r\fP ]
[ \fB\-:\fP[\fBi\fP|\fBo\fP] ]
.sp
\fBNote:\fP No space is allowed between the option flag and the associated arguments.
.SH DESCRIPTION
.sp
\fBxyz2grd\fP reads one or more z or xyz tables and creates a binary grid
file. \fBxyz2grd\fP 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
mean value. As an option (using \fB\-Z\fP), 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 \fB\-Z\fP below.)  Note: \fBxyz2grd\fP does not grid the data,
it simply reformats existing data to a grid structure.  For gridding,
see \fBsurface\fP, \fBgreenspline\fP, \fBnearneighbor\fP, or \fBtriangulate\fP\&.
.SH REQUIRED ARGUMENTS
.INDENT 0.0
.TP
\fB\-G\fP\fIgrdfile\fP
\fIgrdfile\fP is the name of the binary output grid file. (See GRID FILE
FORMAT below.)
.UNINDENT
.INDENT 0.0
.TP
\fB\-I\fP\fIxinc\fP[\fIunit\fP][\fB+e\fP|\fBn\fP][/\fIyinc\fP[\fIunit\fP][\fB+e\fP|\fBn\fP]]
\fIx_inc\fP [and optionally \fIy_inc\fP] is the grid spacing. Optionally,
append a suffix modifier. \fBGeographical (degrees) coordinates\fP: Append
\fBm\fP to indicate arc minutes or \fBs\fP to indicate arc seconds. If one
of the units \fBe\fP, \fBf\fP, \fBk\fP, \fBM\fP, \fBn\fP or \fBu\fP is appended
instead, the increment is assumed to be given in meter, foot, km, Mile,
nautical mile or US survey foot, respectively, and will be converted to
the equivalent degrees longitude at the middle latitude of the region
(the conversion depends on PROJ_ELLIPSOID). If \fIy_inc\fP is given
but set to 0 it will be reset equal to \fIx_inc\fP; otherwise it will be
converted to degrees latitude. \fBAll coordinates\fP: If \fB+e\fP is appended
then the corresponding max \fIx\fP (\fIeast\fP) or \fIy\fP (\fInorth\fP) 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 \fInumber of nodes\fP desired by
appending \fB+n\fP 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 App\-file\-formats for
details. Note: if \fB\-R\fP\fIgrdfile\fP is used then the grid spacing has
already been initialized; use \fB\-I\fP to override the values.
.UNINDENT
.INDENT 0.0
.TP
\fB\-R\fP\fIxmin\fP/\fIxmax\fP/\fIymin\fP/\fIymax\fP[\fB+r\fP][\fB+u\fP\fIunit\fP] (more ...)
Specify the region of interest.  
.UNINDENT
.SH OPTIONAL ARGUMENTS
.INDENT 0.0
.TP
.B \fItable\fP
One or more ASCII [or binary, see \fB\-bi\fP]
files holding z or (x,y,z) values. The xyz triplets do not have to
be sorted. One\-column z tables must be sorted and the \fB\-Z\fP must be set.
.UNINDENT
.INDENT 0.0
.TP
\fB\-A\fP[\fBd\fP|\fBf\fP|\fBl\fP|\fBm\fP|\fBn\fP|\fBr\fP|\fBS\fP|\fBs\fP|\fBu\fP|\fBz\fP]
By default we will calculate mean values if multiple entries fall on
the same node. Use \fB\-A\fP to change this behavior, except it is
ignored if \fB\-Z\fP is given. Append \fBf\fP or \fBs\fP to simply keep the
first or last data point that was assigned to each node. Append
\fBl\fP or \fBu\fP or \fBd\fP to find the lowest (minimum) or upper (maximum) value
or the difference between the maximum and miminum value
at each node, respectively. Append \fBm\fP or \fBr\fP or \fBS\fP to compute mean or
RMS value or standard deviation at each node, respectively. Append \fBn\fP to simply count
the number of data points that were assigned to each node (this only
requires two input columns \fIx\fP and \fIy\fP as \fIz\fP is not consulted). Append
\fBz\fP to sum multiple values that belong to the same node.
.UNINDENT
.INDENT 0.0
.TP
\fB\-D\fP[\fB+x\fP\fIxname\fP][\fB+y\fP\fIyname\fP][\fB+z\fP\fIzname\fP][\fB+s\fP\fIscale\fP][\fB+o\fP\fIoffset\fP][\fB+n\fP\fIinvalid\fP][\fB+t\fP\fItitle\fP][\fB+r\fP\fIremark\fP]
Give one or more combinations for values \fIxname\fP, \fIyname\fP, \fIzname\fP (give the names of those variables
and in square bracket their units, e.g., "distance [km]"), \fIscale\fP (to multiply grid values after
read [normally 1]), \fIoffset\fP (to add to grid after scaling [normally 0]),
\fIinvalid\fP (a value to represent missing data [NaN]), \fItitle\fP (anything you
like), and \fIremark\fP (anything you like). Items not listed will remain untouched.
Give a blank name to completely reset a particular string.
Use quotes to group texts with more than one word.
Note that for geographic grids (\fB\-fg\fP) \fIxname\fP and \fIyname\fP are set automatically.
.UNINDENT
.INDENT 0.0
.TP
\fB\-J\fP\fIparameters\fP (more ...)
Select map projection. Use the \fB\-J\fP syntax to save the georeferencing info as CF\-1 compliant
metadata in netCDF grids. This metadata will be recognized by GDAL.
.UNINDENT
.INDENT 0.0
.TP
\fB\-S\fP[\fIzfile\fP]
Swap the byte\-order of the input only. No grid file is produced. You
must also supply the \fB\-Z\fP option. The output is written to \fIzfile\fP
(or stdout if not supplied).
.UNINDENT
.INDENT 0.0
.TP
\fB\-V\fP[\fIlevel\fP] (more ...)
Select verbosity level [c].  
.UNINDENT
.INDENT 0.0
.TP
\fB\-Z\fP[\fIflags\fP]
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 \fIflags\fP\&. If incoming data represents rows,
make \fIflags\fP start with \fBT\fP(op) if first row is y
= ymax or \fBB\fP(ottom) if first row is y = ymin.
Then, append \fBL\fP or \fBR\fP to indicate that first element is at
left or right end of row. Likewise for column formats: start with
\fBL\fP or \fBR\fP to position first column, and then append \fBT\fP or
\fBB\fP to position first element in a row. Note: These two row/column
indicators are only required for grids; for other tables they do not
apply. For gridline registered grids: If data are periodic in x but
the incoming data do not contain the (redundant) column at x = xmax,
append \fBx\fP\&. For data periodic in y without redundant row at y =
ymax, append \fBy\fP\&. Append \fBs\fP\fIn\fP to skip the first \fIn\fP number
of bytes (probably a header). If the byte\-order or the words needs
to be swapped, append \fBw\fP\&. Select one of several data types (all
binary except \fBa\fP):
.sp
\fBA\fP ASCII representation of one or more floating point values per record
.sp
\fBa\fP ASCII representation of a single item per record
.sp
\fBc\fP int8_t, signed 1\-byte character
.sp
\fBu\fP uint8_t, unsigned 1\-byte character
.sp
\fBh\fP int16_t, signed 2\-byte integer
.sp
\fBH\fP uint16_t, unsigned 2\-byte integer
.sp
\fBi\fP int32_t, signed 4\-byte integer
.sp
\fBI\fP uint32_t, unsigned 4\-byte integer
.sp
\fBl\fP int64_t, long (8\-byte) integer
.sp
\fBL\fP uint64_t, unsigned long (8\-byte) integer
.sp
\fBf\fP 4\-byte floating point single precision
.sp
\fBd\fP 8\-byte floating point double precision
.sp
Default format is scanline orientation of ASCII numbers: \fB\-ZTLa\fP\&.
Note that \fB\-Z\fP only applies to 1\-column input. The difference
between \fBA\fP and \fBa\fP is that the latter can decode both
\fIdate\fP\fBT\fP\fIclock\fP and \fIddd:mm:ss[.xx]\fP formats while the former
is strictly for regular floating point values.
.UNINDENT
.INDENT 0.0
.TP
\fB\-bi\fP[\fIncols\fP][\fBt\fP] (more ...)
Select native binary input. [Default is 3 input columns]. This option only applies
to xyz input files; see \fB\-Z\fP for z tables.
.UNINDENT
.INDENT 0.0
.TP
\fB\-di\fP\fInodata\fP (more ...)
Replace input columns that equal \fInodata\fP with NaN. Also sets nodes with no input xyz triplet to this value
[Default is NaN].
.UNINDENT
.INDENT 0.0
.TP
\fB\-e\fP[\fB~\fP]\fI"pattern"\fP \fB|\fP \fB\-e\fP[\fB~\fP]/\fIregexp\fP/[\fBi\fP] (more ...)
Only accept data records that match the given pattern.  
.UNINDENT
.INDENT 0.0
.TP
\fB\-f\fP[\fBi\fP|\fBo\fP]\fIcolinfo\fP (more ...)
Specify data types of input and/or output columns.  
.UNINDENT
.INDENT 0.0
.TP
\fB\-h\fP[\fBi\fP|\fBo\fP][\fIn\fP][\fB+c\fP][\fB+d\fP][\fB+r\fP\fIremark\fP][\fB+r\fP\fItitle\fP] (more ...)
Skip or produce header record(s). Not used with binary data.
.UNINDENT
.INDENT 0.0
.TP
\fB\-i\fP\fIcols\fP[\fB+l\fP][\fB+s\fP\fIscale\fP][\fB+o\fP\fIoffset\fP][,\fI\&...\fP] (more ...)
Select input columns and transformations (0 is first column).
.UNINDENT
.INDENT 0.0
.TP
\fB\-r\fP (more ...)
Set pixel node registration [gridline].  
.UNINDENT
.INDENT 0.0
.TP
\fB\-:\fP[\fBi\fP|\fBo\fP] (more ...)
Swap 1st and 2nd column on input and/or output.
.UNINDENT
.INDENT 0.0
.TP
\fB\-^\fP or just \fB\-\fP
Print a short message about the syntax of the command, then exits (NOTE: on Windows just use \fB\-\fP).
.TP
\fB\-+\fP or just \fB+\fP
Print an extensive usage (help) message, including the explanation of
any module\-specific option (but not the GMT common options), then exits.
.TP
\fB\-?\fP or no arguments
Print a complete usage (help) message, including the explanation of all options, then exits.
.UNINDENT
.SH GRID VALUES PRECISION
.sp
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.
.SH GRID FILE FORMATS
.sp
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 1\- or 2\-byte integers. To specify the precision, scale and
offset, the user should add the suffix
=\fIID\fP[\fB+s\fP\fIscale\fP][\fB+o\fP\fIoffset\fP][\fB+n\fP\fIinvalid\fP], where
\fIID\fP is a two\-letter identifier of the grid type and precision, and
\fIscale\fP and \fIoffset\fP are optional scale factor and offset to be applied
to all grid values, and \fIinvalid\fP is the value used to indicate missing
data. See grdconvert and Section
grid\-file\-format
of the GMT Technical Reference and Cookbook for more information.
.sp
When writing a netCDF file, the grid is stored by default with the
variable name "z". To specify another variable name \fIvarname\fP, append
\fB?\fP\fIvarname\fP to the file name. Note that you may need to escape the
special meaning of \fB?\fP in your shell program by putting a backslash in
front of it, or by placing the filename and suffix between quotes or
double quotes.
.SH GEOGRAPHICAL AND TIME COORDINATES
.sp
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 \fB\-f\fP or \fB\-R\fP options. For example,
both \fB\-f0x\fP \fB\-f1t\fP and \fB\-R\fP90w/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
gmt.conf file or on the
command line. In addition, the \fBunit\fP attribute of the time variable
will indicate both this unit and epoch.
.SH SWAPPING LIMITATIONS
.sp
All data types can be read, even 64\-bit integers, but internally grids
are stored using floats. Hence, integer values exceeding the float
type\(aqs 23\-bit mantissa may not be represented exactly. When \fB\-S\fP is
used no grids are implied and we read data into an intermediate double
container. This means all but 64\-bit integers can be represented using
the double type\(aqs 53\-bit mantissa.
.SH EXAMPLES
.sp
To create a grid file from the ASCII data in hawaii_grv.xyz, use
.INDENT 0.0
.INDENT 3.5
.INDENT 0.0
.TP
.B gmt xyz2grd hawaii_grv.xyz \-D+xdegree+ydegree+zGal+t"Hawaiian Gravity"+r"GRS\-80 Ellipsoid used" 
\-Ghawaii_grv_new.nc \-R198/208/18/25 \-I5m \-V
.UNINDENT
.UNINDENT
.UNINDENT
.sp
To create a grid file from the raw binary (3\-column, single\-precision
scanline\-oriented data raw.b, use
.INDENT 0.0
.INDENT 3.5
gmt xyz2grd raw.b \-D+xm+ym+zm \-Graw.nc \-R0/100/0/100 \-I1 \-V \-Z \-bi3f
.UNINDENT
.UNINDENT
.sp
To make a grid file from the raw binary USGS DEM (short integer
scanline\-oriented data topo30.b 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
.INDENT 0.0
.INDENT 3.5
gmt xyz2grd topo30.b \-D+xm+ym+zm \-Gustopo.nc \-R234/294/24/50 \-I30s \-di\-9999 \-ZTLhw
.UNINDENT
.UNINDENT
.sp
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
.INDENT 0.0
.INDENT 3.5
gmt xyz2grd floats.bin \-Snew_floats.bin \-V \-Zf
.UNINDENT
.UNINDENT
.SH SEE ALSO
.sp
gmt,
grd2xyz,
grdedit,
grdconvert,
greenspline,
nearneighbor,
surface,
triangulate
.SH COPYRIGHT
2019, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe
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