1GDAL_GRID(1) GDAL GDAL_GRID(1)
2
6 gdal_grid - Creates regular grid from the scattered data.
7
9 gdal_grid [-ot {Byte/Int16/UInt16/UInt32/Int32/Float32/Float64/
10 CInt16/CInt32/CFloat32/CFloat64}]
11 [-of format] [-co "NAME=VALUE"]
12 [-zfield field_name] [-z_increase increase_value] [-z_multiply multiply_value]
13 [-a_srs srs_def] [-spat xmin ymin xmax ymax]
14 [-clipsrc <xmin ymin xmax ymax>|WKT|datasource|spat_extent]
15 [-clipsrcsql sql_statement] [-clipsrclayer layer]
16 [-clipsrcwhere expression]
17 [-l layername]* [-where expression] [-sql select_statement]
18 [-txe xmin xmax] [-tye ymin ymax] [-tr xres yres] [-outsize xsize ysize]
19 [-a algorithm[:parameter1=value1]*] [-q]
20 <src_datasource> <dst_filename>
21
23 This program creates regular grid (raster) from the scattered data read
24 from the OGR datasource. Input data will be interpolated to fill grid
25 nodes with values, you can choose from various interpolation methods.
26 It is possible to set the GDAL_NUM_THREADS configuration option to par‐
28 allelize the processing. The value to specify is the number of worker
29 threads, or ALL_CPUS to use all the cores/CPUs of the computer.
30 -ot <type>
32 Force the output image bands to have a specific data type sup‐
33 ported by the driver, which may be one of the following: Byte,
34 UInt16, Int16, UInt32, Int32, Float32, Float64, CInt16, CInt32,
35 CFloat32 or CFloat64.
36 -of <format>
38 Select the output format. Starting with GDAL 2.3, if not speci‐
39 fied, the format is guessed from the extension (previously was
40 GTiff). Use the short format name.
41 -txe <xmin> <xmax>
43 Set georeferenced X extents of output file to be created.
44 -tye <ymin> <ymax>
46 Set georeferenced Y extents of output file to be created.
47 -tr <xres> <yres>
49 Set output file resolution (in target georeferenced units).
50 Note that -tr just works in combination with a valid input from
51 -txe and -tye
52 New in version 3.2.
54 -outsize <xsize ysize>
57 Set the size of the output file in pixels and lines. Note that
58 -outsize cannot be used with -tr
59 -a_srs <srs_def>
61 Override the projection for the output file. The <i>srs_def>
62 may be any of the usual GDAL/OGR forms, complete WKT, PROJ.4,
63 EPSG:n or a file containing the WKT. No reprojection is done.
64 -zfield <field_name>
66 Identifies an attribute field on the features to be used to get
67 a Z value from. This value overrides Z value read from feature
68 geometry record (naturally, if you have a Z value in geometry,
69 otherwise you have no choice and should specify a field name
70 containing Z value).
71 -z_increase <increase_value>
73 Addition to the attribute field on the features to be used to
74 get a Z value from. The addition should be the same unit as Z
75 value. The result value will be Z value + Z increase value. The
76 default value is 0.
77 -z_multiply <multiply_value>
79 This is multiplication ratio for Z field. This can be used for
80 shift from e.g. foot to meters or from elevation to deep. The
81 result value will be (Z value + Z increase value) * Z multiply
82 value. The default value is 1.
83 -a <[algorithm[:parameter1=value1][:parameter2=value2]...]>
85 Set the interpolation algorithm or data metric name and (option‐
86 ally) its parameters. See Interpolation algorithms and Data met‐
87 rics sections for further discussion of available options.
88 -spat <xmin> <ymin> <xmax> <ymax>
90 Adds a spatial filter to select only features contained within
91 the bounding box described by (xmin, ymin) - (xmax, ymax).
92 -clipsrc [xmin ymin xmax ymax]|WKT|datasource|spat_extent
94 Adds a spatial filter to select only features contained within
95 the specified bounding box (expressed in source SRS), WKT geome‐
96 try (POLYGON or MULTIPOLYGON), from a datasource or to the spa‐
97 tial extent of the -spat option if you use the spat_extent key‐
98 word. When specifying a datasource, you will generally want to
99 use it in combination of the -clipsrclayer, -clipsrcwhere or
100 -clipsrcsql options.
101 -clipsrcsql <sql_statement>
103 Select desired geometries using an SQL query instead.
104 -clipsrclayer <layername>
106 Select the named layer from the source clip datasource.
107 -clipsrcwhere <expression>
109 Restrict desired geometries based on attribute query.
110 -l <layername>
112 Indicates the layer(s) from the datasource that will be used for
113 input features. May be specified multiple times, but at least
114 one layer name or a -sql option must be specified.
115 -where <expression>
117 An optional SQL WHERE style query expression to be applied to
118 select features to process from the input layer(s).
119 -sql <select_statement>
121 An SQL statement to be evaluated against the datasource to pro‐
122 duce a virtual layer of features to be processed.
123 -co <NAME=VALUE>
125 Many formats have one or more optional creation options that can
126 be used to control particulars about the file created. For in‐
127 stance, the GeoTIFF driver supports creation options to control
128 compression, and whether the file should be tiled.
129 The creation options available vary by format driver, and some
131 simple formats have no creation options at all. A list of op‐
132 tions supported for a format can be listed with the --formats
133 command line option but the documentation for the format is the
134 definitive source of information on driver creation options.
135 See raster_drivers format specific documentation for legal cre‐
136 ation options for each format.
137 -q Suppress progress monitor and other non-error output.
139 <src_datasource>
141 Any OGR supported readable datasource.
142 <dst_filename>
144 The GDAL supported output file.
145
147 There are number of interpolation algorithms to choose from.
148 More details about them can also be found in gdal_grid_tut
150 invdist
152 Inverse distance to a power. This is default algorithm. It has follow‐
153 ing parameters:
154 • power: Weighting power (default 2.0).
156 • smoothing: Smoothing parameter (default 0.0).
158 • radius1: The first radius (X axis if rotation angle is 0) of search
160 ellipse. Set this parameter to zero to use whole point array. De‐
161 fault is 0.0.
162 • radius2: The second radius (Y axis if rotation angle is 0) of search
164 ellipse. Set this parameter to zero to use whole point array. De‐
165 fault is 0.0.
166 • angle: Angle of search ellipse rotation in degrees (counter clock‐
168 wise, default 0.0).
169 • max_points: Maximum number of data points to use. Do not search for
171 more points than this number. This is only used if search ellipse is
172 set (both radii are non-zero). Zero means that all found points
173 should be used. Default is 0.
174 • min_points: Minimum number of data points to use. If less amount of
176 points found the grid node considered empty and will be filled with
177 NODATA marker. This is only used if search ellipse is set (both radii
178 are non-zero). Default is 0.
179 • nodata: NODATA marker to fill empty points (default 0.0).
181 invdistnn
183 New in version 2.1.
184 Inverse distance to a power with nearest neighbor searching, ideal when
187 max_points is used. It has following parameters:
188 • power: Weighting power (default 2.0).
190 • smoothing: Smoothing parameter (default 0.0).
192 • radius: The radius of the search circle, which should be non-zero.
194 Default is 1.0.
195 • max_points: Maximum number of data points to use. Do not search for
197 more points than this number. Found points will be ranked from near‐
198 est to furthest distance when weighting. Default is 12.
199 • min_points: Minimum number of data points to use. If less amount of
201 points found the grid node is considered empty and will be filled
202 with NODATA marker. Default is 0.
203 • nodata: NODATA marker to fill empty points (default 0.0).
205 average
207 Moving average algorithm. It has following parameters:
208 • radius1: The first radius (X axis if rotation angle is 0) of search
210 ellipse. Set this parameter to zero to use whole point array. De‐
211 fault is 0.0.
212 • radius2: The second radius (Y axis if rotation angle is 0) of search
214 ellipse. Set this parameter to zero to use whole point array. De‐
215 fault is 0.0.
216 • angle: Angle of search ellipse rotation in degrees (counter clock‐
218 wise, default 0.0).
219 • min_points: Minimum number of data points to use. If less amount of
221 points found the grid node considered empty and will be filled with
222 NODATA marker. Default is 0.
223 • nodata: NODATA marker to fill empty points (default 0.0).
225 Note, that it is essential to set search ellipse for moving average
227 method. It is a window that will be averaged when computing grid nodes
228 values.
229 nearest
231 Nearest neighbor algorithm. It has following parameters:
232 • radius1: The first radius (X axis if rotation angle is 0) of search
234 ellipse. Set this parameter to zero to use whole point array. De‐
235 fault is 0.0.
236 • radius2: The second radius (Y axis if rotation angle is 0) of search
238 ellipse. Set this parameter to zero to use whole point array. De‐
239 fault is 0.0.
240 • angle: Angle of search ellipse rotation in degrees (counter clock‐
242 wise, default 0.0).
243 • nodata: NODATA marker to fill empty points (default 0.0).
245 linear
247 New in version 2.1.
248 Linear interpolation algorithm.
251 The Linear method performs linear interpolation by computing a Delaunay
253 triangulation of the point cloud, finding in which triangle of the tri‐
254 angulation the point is, and by doing linear interpolation from its
255 barycentric coordinates within the triangle. If the point is not in
256 any triangle, depending on the radius, the algorithm will use the value
257 of the nearest point or the nodata value.
258 It has following parameters:
260 • radius: In case the point to be interpolated does not fit into a tri‐
262 angle of the Delaunay triangulation, use that maximum distance to
263 search a nearest neighbour, or use nodata otherwise. If set to -1,
264 the search distance is infinite. If set to 0, nodata value will be
265 always used. Default is -1.
266 • nodata: NODATA marker to fill empty points (default 0.0).
268
270 Besides the interpolation functionality ref gdal_grid can be used to
271 compute some data metrics using the specified window and output grid
272 geometry. These metrics are:
273 • minimum: Minimum value found in grid node search ellipse.
275 • maximum: Maximum value found in grid node search ellipse.
277 • range: A difference between the minimum and maximum values found in
279 grid node search ellipse.
280 • count: A number of data points found in grid node search ellipse.
282 • average_distance: An average distance between the grid node (center
284 of the search ellipse) and all of the data points found in grid node
285 search ellipse.
286 • average_distance_pts: An average distance between the data points
288 found in grid node search ellipse. The distance between each pair of
289 points within ellipse is calculated and average of all distances is
290 set as a grid node value.
291 All the metrics have the same set of options:
293 • radius1: The first radius (X axis if rotation angle is 0) of search
295 ellipse. Set this parameter to zero to use whole point array. De‐
296 fault is 0.0.
297 • radius2: The second radius (Y axis if rotation angle is 0) of search
299 ellipse. Set this parameter to zero to use whole point array. De‐
300 fault is 0.0.
301 • angle: Angle of search ellipse rotation in degrees (counter clock‐
303 wise, default 0.0).
304 • min_points: Minimum number of data points to use. If less amount of
306 points found the grid node considered empty and will be filled with
307 NODATA marker. This is only used if search ellipse is set (both radii
308 are non-zero). Default is 0.
309 • nodata: NODATA marker to fill empty points (default 0.0).
311
313 Often you have a text file with a list of comma separated XYZ values to
314 work with (so called CSV file). You can easily use that kind of data
315 source in ref gdal_grid. All you need is create a virtual dataset
316 header (VRT) for you CSV file and use it as input datasource for ref
317 gdal_grid. You can find details on VRT format at vector.vrt description
318 page.
319 Here is a small example. Let we have a CSV file called <i>dem.csv> con‐
321 taining
322 Easting,Northing,Elevation
324 86943.4,891957,139.13
325 87124.3,892075,135.01
326 86962.4,892321,182.04
327 87077.6,891995,135.01
328 ...
329 For above data we will create <i>dem.vrt> header with the following
331 content:
332 <OGRVRTDataSource>
334 <OGRVRTLayer name="dem">
335 <SrcDataSource>dem.csv</SrcDataSource>
336 <GeometryType>wkbPoint</GeometryType>
337 <GeometryField encoding="PointFromColumns" x="Easting" y="Northing" z="Elevation"/>
338 </OGRVRTLayer>
339 </OGRVRTDataSource>
340 This description specifies so called 2.5D geometry with three coordi‐
342 nates X, Y and Z. Z value will be used for interpolation. Now you can
343 use <i>dem.vrt> with all OGR programs (start with ref ogrinfo to test
344 that everything works fine). The datasource will contain single layer
345 called <i>"dem"> filled with point features constructed from values in
346 CSV file. Using this technique you can handle CSV files with more than
347 three columns, switch columns, etc.
348 If your CSV file does not contain column headers then it can be handled
350 in the following way:
351 <GeometryField encoding="PointFromColumns" x="field_1" y="field_2" z="field_3"/>
353 The vector.csv description page contains details on CSV format sup‐
355 ported by GDAL/OGR.
356
358 This utility is also callable from C with GDALGrid().
359
361 The following would create raster TIFF file from VRT datasource de‐
362 scribed in Reading comma separated values section using the inverse
363 distance to a power method. Values to interpolate will be read from Z
364 value of geometry record.
365 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
367 The next command does the same thing as the previous one, but reads
369 values to interpolate from the attribute field specified with
370 <b>-zfield</b> option instead of geometry record. So in this case X and
371 Y coordinates are being taken from geometry and Z is being taken from
372 the <i>"Elevation"> field. The GDAL_NUM_THREADS is also set to paral‐
373 lelize the computation.
374 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
376
378 Andrey Kiselev <dron@ak4719.spb.edu>
379
381 1998-2022
382 May 04, 2022 GDAL_GRID(1)