Provided by: gdal-bin_3.4.1+dfsg-1build4_amd64 
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 parallelize 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 supported 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 specified, 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 (optionally) its parameters. See
Interpolation algorithms and Data metrics 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 geometry (POLYGON or MULTIPOLYGON), from a datasource or to the
spatial extent of the -spat option if you use the spat_extent keyword. 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 produce 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 instance, 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 options 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 creation 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 following 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. Default 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. Default is 0.0.
• angle: Angle of search ellipse rotation in degrees (counter clockwise, 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 nearest 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. Default 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. Default is 0.0.
• angle: Angle of search ellipse rotation in degrees (counter clockwise, 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. Default 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. Default is 0.0.
• angle: Angle of search ellipse rotation in degrees (counter clockwise, 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 triangulation 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 triangle 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. Default 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. Default is 0.0.
• angle: Angle of search ellipse rotation in degrees (counter clockwise, 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> containing
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 coordinates 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 supported 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 described 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 parallelize 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)