GDAL_GRID(1) GDAL GDAL_GRID(1)
NAME
gdal_grid - Creates regular grid from the scattered data.
SYNOPSIS
gdal_grid [-ot {Byte/Int16/UInt16/UInt32/Int32/Float32/Float64/
CInt16/CInt32/CFloat32/CFloat64}]
[-of format] [-co "NAME=VALUE"]
[-zfield field_name] [-z_increase increase_value] [-z_multiply multiply_value]
[-a_srs srs_def] [-spat xmin ymin xmax ymax]
[-clipsrc <xmin ymin xmax ymax>|WKT|datasource|spat_extent]
[-clipsrcsql sql_statement] [-clipsrclayer layer]
[-clipsrcwhere expression]
[-l layername]* [-where expression] [-sql select_statement]
[-txe xmin xmax] [-tye ymin ymax] [-tr xres yres] [-outsize xsize ysize]
[-a algorithm[:parameter1=value1]*] [-q]
<src_datasource> <dst_filename>
DESCRIPTION
This program creates regular grid (raster) from the scattered data read
from the OGR datasource. Input data will be interpolated to fill grid
nodes with values, you can choose from various interpolation methods.
It is possible to set the GDAL_NUM_THREADS configuration option to par-
allelize the processing. The value to specify is the number of worker
threads, or ALL_CPUS to use all the cores/CPUs of the computer.
-ot <type>
Force the output image bands to have a specific data type sup-
ported by the driver, which may be one of the following: Byte,
UInt16, Int16, UInt32, Int32, Float32, Float64, CInt16, CInt32,
CFloat32 or CFloat64.
-of <format>
Select the output format. Starting with GDAL 2.3, if not speci-
fied, the format is guessed from the extension (previously was
GTiff). Use the short format name.
-txe <xmin> <xmax>
Set georeferenced X extents of output file to be created.
-tye <ymin> <ymax>
Set georeferenced Y extents of output file to be created.
-tr <xres> <yres>
Set output file resolution (in target georeferenced units).
Note that -tr just works in combination with a valid input from
-txe and -tye
New in version 3.2.
-outsize <xsize ysize>
Set the size of the output file in pixels and lines. Note that
-outsize cannot be used with -tr
-a_srs <srs_def>
Override the projection for the output file. The <i>srs_def>
may be any of the usual GDAL/OGR forms, complete WKT, PROJ.4,
EPSG:n or a file containing the WKT. No reprojection is done.
-zfield <field_name>
Identifies an attribute field on the features to be used to get
a Z value from. This value overrides Z value read from feature
geometry record (naturally, if you have a Z value in geometry,
otherwise you have no choice and should specify a field name
containing Z value).
-z_increase <increase_value>
Addition to the attribute field on the features to be used to
get a Z value from. The addition should be the same unit as Z
value. The result value will be Z value + Z increase value. The
default value is 0.
-z_multiply <multiply_value>
This is multiplication ratio for Z field. This can be used for
shift from e.g. foot to meters or from elevation to deep. The
result value will be (Z value + Z increase value) * Z multiply
value. The default value is 1.
-a <[algorithm[:parameter1=value1][:parameter2=value2]...]>
Set the interpolation algorithm or data metric name and (option-
ally) its parameters. See Interpolation algorithms and Data met-
rics sections for further discussion of available options.
-spat <xmin> <ymin> <xmax> <ymax>
Adds a spatial filter to select only features contained within
the bounding box described by (xmin, ymin) - (xmax, ymax).
-clipsrc [xmin ymin xmax ymax]|WKT|datasource|spat_extent
Adds a spatial filter to select only features contained within
the specified bounding box (expressed in source SRS), WKT geome-
try (POLYGON or MULTIPOLYGON), from a datasource or to the spa-
tial extent of the -spat option if you use the spat_extent key-
word. When specifying a datasource, you will generally want to
use it in combination of the -clipsrclayer, -clipsrcwhere or
-clipsrcsql options.
-clipsrcsql <sql_statement>
Select desired geometries using an SQL query instead.
-clipsrclayer <layername>
Select the named layer from the source clip datasource.
-clipsrcwhere <expression>
Restrict desired geometries based on attribute query.
-l <layername>
Indicates the layer(s) from the datasource that will be used for
input features. May be specified multiple times, but at least
one layer name or a -sql option must be specified.
-where <expression>
An optional SQL WHERE style query expression to be applied to
select features to process from the input layer(s).
-sql <select_statement>
An SQL statement to be evaluated against the datasource to pro-
duce a virtual layer of features to be processed.
-co <NAME=VALUE>
Many formats have one or more optional creation options that can
be used to control particulars about the file created. For in-
stance, the GeoTIFF driver supports creation options to control
compression, and whether the file should be tiled.
The creation options available vary by format driver, and some
simple formats have no creation options at all. A list of op-
tions supported for a format can be listed with the --formats
command line option but the documentation for the format is the
definitive source of information on driver creation options.
See raster_drivers format specific documentation for legal cre-
ation options for each format.
-q Suppress progress monitor and other non-error output.
<src_datasource>
Any OGR supported readable datasource.
<dst_filename>
The GDAL supported output file.
INTERPOLATION ALGORITHMS
There are number of interpolation algorithms to choose from.
More details about them can also be found in gdal_grid_tut
invdist
Inverse distance to a power. This is default algorithm. It has follow-
ing parameters:
• power: Weighting power (default 2.0).
• smoothing: Smoothing parameter (default 0.0).
• radius1: The first radius (X axis if rotation angle is 0) of search
ellipse. Set this parameter to zero to use whole point array. De-
fault is 0.0.
• radius2: The second radius (Y axis if rotation angle is 0) of search
ellipse. Set this parameter to zero to use whole point array. De-
fault is 0.0.
• angle: Angle of search ellipse rotation in degrees (counter clock-
wise, default 0.0).
• max_points: Maximum number of data points to use. Do not search for
more points than this number. This is only used if search ellipse is
set (both radii are non-zero). Zero means that all found points
should be used. Default is 0.
• min_points: Minimum number of data points to use. If less amount of
points found the grid node considered empty and will be filled with
NODATA marker. This is only used if search ellipse is set (both radii
are non-zero). Default is 0.
• nodata: NODATA marker to fill empty points (default 0.0).
invdistnn
New in version 2.1.
Inverse distance to a power with nearest neighbor searching, ideal when
max_points is used. It has following parameters:
• power: Weighting power (default 2.0).
• smoothing: Smoothing parameter (default 0.0).
• radius: The radius of the search circle, which should be non-zero.
Default is 1.0.
• max_points: Maximum number of data points to use. Do not search for
more points than this number. Found points will be ranked from near-
est to furthest distance when weighting. Default is 12.
• min_points: Minimum number of data points to use. If less amount of
points found the grid node is considered empty and will be filled
with NODATA marker. Default is 0.
• nodata: NODATA marker to fill empty points (default 0.0).
average
Moving average algorithm. It has following parameters:
• radius1: The first radius (X axis if rotation angle is 0) of search
ellipse. Set this parameter to zero to use whole point array. De-
fault is 0.0.
• radius2: The second radius (Y axis if rotation angle is 0) of search
ellipse. Set this parameter to zero to use whole point array. De-
fault is 0.0.
• angle: Angle of search ellipse rotation in degrees (counter clock-
wise, default 0.0).
• min_points: Minimum number of data points to use. If less amount of
points found the grid node considered empty and will be filled with
NODATA marker. Default is 0.
• nodata: NODATA marker to fill empty points (default 0.0).
Note, that it is essential to set search ellipse for moving average
method. It is a window that will be averaged when computing grid nodes
values.
nearest
Nearest neighbor algorithm. It has following parameters:
• radius1: The first radius (X axis if rotation angle is 0) of search
ellipse. Set this parameter to zero to use whole point array. De-
fault is 0.0.
• radius2: The second radius (Y axis if rotation angle is 0) of search
ellipse. Set this parameter to zero to use whole point array. De-
fault is 0.0.
• angle: Angle of search ellipse rotation in degrees (counter clock-
wise, default 0.0).
• nodata: NODATA marker to fill empty points (default 0.0).
linear
New in version 2.1.
Linear interpolation algorithm.
The Linear method performs linear interpolation by computing a Delaunay
triangulation of the point cloud, finding in which triangle of the tri-
angulation the point is, and by doing linear interpolation from its
barycentric coordinates within the triangle. If the point is not in
any triangle, depending on the radius, the algorithm will use the value
of the nearest point or the nodata value.
It has following parameters:
• radius: In case the point to be interpolated does not fit into a tri-
angle of the Delaunay triangulation, use that maximum distance to
search a nearest neighbour, or use nodata otherwise. If set to -1,
the search distance is infinite. If set to 0, nodata value will be
always used. Default is -1.
• nodata: NODATA marker to fill empty points (default 0.0).
DATA METRICS
Besides the interpolation functionality ref gdal_grid can be used to
compute some data metrics using the specified window and output grid
geometry. These metrics are:
• minimum: Minimum value found in grid node search ellipse.
• maximum: Maximum value found in grid node search ellipse.
• range: A difference between the minimum and maximum values found in
grid node search ellipse.
• count: A number of data points found in grid node search ellipse.
• average_distance: An average distance between the grid node (center
of the search ellipse) and all of the data points found in grid node
search ellipse.
• average_distance_pts: An average distance between the data points
found in grid node search ellipse. The distance between each pair of
points within ellipse is calculated and average of all distances is
set as a grid node value.
All the metrics have the same set of options:
• radius1: The first radius (X axis if rotation angle is 0) of search
ellipse. Set this parameter to zero to use whole point array. De-
fault is 0.0.
• radius2: The second radius (Y axis if rotation angle is 0) of search
ellipse. Set this parameter to zero to use whole point array. De-
fault is 0.0.
• angle: Angle of search ellipse rotation in degrees (counter clock-
wise, default 0.0).
• min_points: Minimum number of data points to use. If less amount of
points found the grid node considered empty and will be filled with
NODATA marker. This is only used if search ellipse is set (both radii
are non-zero). Default is 0.
• nodata: NODATA marker to fill empty points (default 0.0).
READING COMMA SEPARATED VALUES
Often you have a text file with a list of comma separated XYZ values to
work with (so called CSV file). You can easily use that kind of data
source in ref gdal_grid. All you need is create a virtual dataset
header (VRT) for you CSV file and use it as input datasource for ref
gdal_grid. You can find details on VRT format at vector.vrt description
page.
Here is a small example. Let we have a CSV file called <i>dem.csv> con-
taining
Easting,Northing,Elevation
86943.4,891957,139.13
87124.3,892075,135.01
86962.4,892321,182.04
87077.6,891995,135.01
...
For above data we will create <i>dem.vrt> header with the following
content:
<OGRVRTDataSource>
<OGRVRTLayer name="dem">
<SrcDataSource>dem.csv</SrcDataSource>
<GeometryType>wkbPoint</GeometryType>
<GeometryField encoding="PointFromColumns" x="Easting" y="Northing" z="Elevation"/>
</OGRVRTLayer>
</OGRVRTDataSource>
This description specifies so called 2.5D geometry with three coordi-
nates X, Y and Z. Z value will be used for interpolation. Now you can
use <i>dem.vrt> with all OGR programs (start with ref ogrinfo to test
that everything works fine). The datasource will contain single layer
called <i>"dem"> filled with point features constructed from values in
CSV file. Using this technique you can handle CSV files with more than
three columns, switch columns, etc.
If your CSV file does not contain column headers then it can be handled
in the following way:
<GeometryField encoding="PointFromColumns" x="field_1" y="field_2" z="field_3"/>
The vector.csv description page contains details on CSV format sup-
ported by GDAL/OGR.
C API
This utility is also callable from C with GDALGrid().
EXAMPLES
The following would create raster TIFF file from VRT datasource de-
scribed in Reading comma separated values section using the inverse
distance to a power method. Values to interpolate will be read from Z
value of geometry record.
gdal_grid -a invdist:power=2.0:smoothing=1.0 -txe 85000 89000 -tye 894000 890000 -outsize 400 400 -of GTiff -ot Float64 -l dem dem.vrt dem.tiff
The next command does the same thing as the previous one, but reads
values to interpolate from the attribute field specified with
<b>-zfield</b> option instead of geometry record. So in this case X and
Y coordinates are being taken from geometry and Z is being taken from
the <i>"Elevation"> field. The GDAL_NUM_THREADS is also set to paral-
lelize the computation.
gdal_grid -zfield "Elevation" -a invdist:power=2.0:smoothing=1.0 -txe 85000 89000 -tye 894000 890000 -outsize 400 400 -of GTiff -ot Float64 -l dem dem.vrt dem.tiff --config GDAL_NUM_THREADS ALL_CPUS
AUTHOR
Andrey Kiselev <dron@ak4719.spb.edu>
COPYRIGHT
1998-2021
Dec 27, 2021 GDAL_GRID(1)
Generated by dwww version 1.14 on Fri Jan 24 09:20:04 CET 2025.