1gdal_grid(1) General Commands Manual gdal_grid(1)
2
6 gdal_gridCreates 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] [-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 Starting with GDAL 1.10, it is possible to set the GDAL_NUM_THREADS
28 configuration option to parallelize the processing. The value to
29 specify is the number of worker threads, or ALL_CPUS to use all the
30 cores/CPUs of the computer.
31 -ot type:
33 For the output bands to be of the indicated data type.
34 -of format:
36 Select the output format. Starting with GDAL 2.3, if not specified,
37 the format is guessed from the extension (previously was GTiff).
38 Use the short format name.
39 -txe xmin xmax:
41 Set georeferenced X extents of output file to be created.
42 -tye ymin ymax:
44 Set georeferenced Y extents of output file to be created.
45 -outsize xsize ysize:
47 Set the size of the output file in pixels and lines.
48 -a_srs srs_def:
50 Override the projection for the output file. The srs_def may be any
51 of the usual GDAL/OGR forms, complete WKT, PROJ.4, EPSG:n or a file
52 containing the WKT. No reprojection is done.
53 -zfield field_name:
55 Identifies an attribute field on the features to be used to get a Z
56 value from. This value overrides Z value read from feature geometry
57 record (naturally, if you have a Z value in geometry, otherwise you
58 have no choice and should specify a field name containing Z value).
59 -z_increase increase_value:
61 Addition to the attribute field on the features to be used to get a
62 Z value from. The addition should be the same unit as Z value. The
63 result value will be Z value + Z increase value. The default value
64 is 0.
65 -z_multiply multiply_value:
67 This is multiplication ratio for Z field. This can be used for
68 shift from e.g. foot to meters or from elevation to deep. The
69 result value will be (Z value + Z increase value) * Z multiply
70 value. The default value is 1.
71 -a [algorithm[:parameter1=value1][:parameter2=value2]...]:
73 Set the interpolation algorithm or data metric name and
74 (optionally) its parameters. See INTERPOLATION ALGORITHMS and DATA
75 METRICS sections for further discussion of available options.
76 -spat xmin ymin xmax ymax:
78 Adds a spatial filter to select only features contained within the
79 bounding box described by (xmin, ymin) - (xmax, ymax).
80 -clipsrc [xmin ymin xmax ymax]|WKT|datasource|spat_extent:
82 Adds a spatial filter to select only features contained within the
83 specified bounding box (expressed in source SRS), WKT geometry
84 (POLYGON or MULTIPOLYGON), from a datasource or to the spatial
85 extent of the -spat option if you use the spat_extent keyword. When
86 specifying a datasource, you will generally want to use it in
87 combination of the -clipsrclayer, -clipsrcwhere or -clipsrcsql
88 options.
89 -clipsrcsql sql_statement:
91 Select desired geometries using an SQL query instead.
92 -clipsrclayer layername:
94 Select the named layer from the source clip datasource.
95 -clipsrcwhere expression:
97 Restrict desired geometries based on attribute query.
98 -l layername:
100 Indicates the layer(s) from the datasource that will be used for
101 input features. May be specified multiple times, but at least one
102 layer name or a -sql option must be specified.
103 -where expression:
105 An optional SQL WHERE style query expression to be applied to
106 select features to process from the input layer(s).
107 -sql select_statement:
109 An SQL statement to be evaluated against the datasource to produce
110 a virtual layer of features to be processed.
111 -co 'NAME=VALUE':
113 Passes a creation option to the output format driver. Multiple -co
114 options may be listed. See format specific documentation for legal
115 creation options for each format.
116 -q:
118 Suppress progress monitor and other non-error output.
119 src_datasource:
121 Any OGR supported readable datasource.
122 dst_filename:
124 The GDAL supported output file.
125
127 There are number of interpolation algorithms to choose from.
128 invdist
130 Inverse distance to a power. This is default algorithm. It has
131 following parameters:
132 power:
134 Weighting power (default 2.0).
135 smoothing:
137 Smoothing parameter (default 0.0).
138 radius1:
140 The first radius (X axis if rotation angle is 0) of search ellipse.
141 Set this parameter to zero to use whole point array. Default is
142 0.0.
143 radius2:
145 The second radius (Y axis if rotation angle is 0) of search
146 ellipse. Set this parameter to zero to use whole point array.
147 Default is 0.0.
148 angle:
150 Angle of search ellipse rotation in degrees (counter clockwise,
151 default 0.0).
152 max_points:
154 Maximum number of data points to use. Do not search for more points
155 than this number. This is only used if search ellipse is set (both
156 radii are non-zero). Zero means that all found points should be
157 used. Default is 0.
158 min_points:
160 Minimum number of data points to use. If less amount of points
161 found the grid node considered empty and will be filled with NODATA
162 marker. This is only used if search ellipse is set (both radii are
163 non-zero). Default is 0.
164 nodata:
166 NODATA marker to fill empty points (default 0.0).
167 invdistnn
169 (Since GDAL 2.1) Inverse distance to a power with nearest neighbor
170 searching, ideal when max_points is used. It has following parameters:
171 power:
173 Weighting power (default 2.0).
174 smoothing:
176 Smoothing parameter (default 0.0).
177 radius:
179 The radius of the search circle, which should be non-zero. Default
180 is 1.0.
181 max_points:
183 Maximum number of data points to use. Do not search for more points
184 than this number. Found points will be ranked from nearest to
185 furthest distance when weighting. Default is 12.
186 min_points:
188 Minimum number of data points to use. If less amount of points
189 found the grid node is considered empty and will be filled with
190 NODATA marker. Default is 0.
191 nodata:
193 NODATA marker to fill empty points (default 0.0).
194 average
196 Moving average algorithm. It has following parameters:
197 radius1:
199 The first radius (X axis if rotation angle is 0) of search ellipse.
200 Set this parameter to zero to use whole point array. Default is
201 0.0.
202 radius2:
204 The second radius (Y axis if rotation angle is 0) of search
205 ellipse. Set this parameter to zero to use whole point array.
206 Default is 0.0.
207 angle:
209 Angle of search ellipse rotation in degrees (counter clockwise,
210 default 0.0).
211 min_points:
213 Minimum number of data points to use. If less amount of points
214 found the grid node considered empty and will be filled with NODATA
215 marker. Default is 0.
216 nodata:
218 NODATA marker to fill empty points (default 0.0).
219 Note, that it is essential to set search ellipse for moving average
221 method. It is a window that will be averaged when computing grid nodes
222 values.
223 nearest
225 Nearest neighbor algorithm. It has following parameters:
226 radius1:
228 The first radius (X axis if rotation angle is 0) of search ellipse.
229 Set this parameter to zero to use whole point array. Default is
230 0.0.
231 radius2:
233 The second radius (Y axis if rotation angle is 0) of search
234 ellipse. Set this parameter to zero to use whole point array.
235 Default is 0.0.
236 angle:
238 Angle of search ellipse rotation in degrees (counter clockwise,
239 default 0.0).
240 nodata:
242 NODATA marker to fill empty points (default 0.0).
243 linear
245 (Since GDAL 2.1) Linear interpolation algorithm.
246 The Linear method performs linear interpolation by computing a Delaunay
248 triangulation of the point cloud, finding in which triangle of the
249 triangulation the point is, and by doing linear interpolation from its
250 barycentric coordinates within the triangle. If the point is not in any
251 triangle, depending on the radius, the algorithm will use the value of
252 the nearest point or the nodata value.
253 It has following parameters:
255 radius:
257 In case the point to be interpolated does not fit into a triangle
258 of the Delaunay triangulation, use that maximum distance to search
259 a nearest neighbour, or use nodata otherwise. If set to -1, the
260 search distance is infinite. If set to 0, nodata value will be
261 always used. Default is -1.
262 nodata:
264 NODATA marker to fill empty points (default 0.0).
265
267 Besides the interpolation functionality gdal_grid can be used to
268 compute some data metrics using the specified window and output grid
269 geometry. These metrics are:
270 minimum:
272 Minimum value found in grid node search ellipse.
273 maximum:
275 Maximum value found in grid node search ellipse.
276 range:
278 A difference between the minimum and maximum values found in grid
279 node search ellipse.
280 count:
282 A number of data points found in grid node search ellipse.
283 average_distance:
285 An average distance between the grid node (center of the search
286 ellipse) and all of the data points found in grid node search
287 ellipse.
288 average_distance_pts:
290 An average distance between the data points found in grid node
291 search ellipse. The distance between each pair of points within
292 ellipse is calculated and average of all distances is set as a grid
293 node value.
294 All the metrics have the same set of options:
296 radius1:
298 The first radius (X axis if rotation angle is 0) of search ellipse.
299 Set this parameter to zero to use whole point array. Default is
300 0.0.
301 radius2:
303 The second radius (Y axis if rotation angle is 0) of search
304 ellipse. Set this parameter to zero to use whole point array.
305 Default is 0.0.
306 angle:
308 Angle of search ellipse rotation in degrees (counter clockwise,
309 default 0.0).
310 min_points:
312 Minimum number of data points to use. If less amount of points
313 found the grid node considered empty and will be filled with NODATA
314 marker. This is only used if search ellipse is set (both radii are
315 non-zero). Default is 0.
316 nodata:
318 NODATA marker to fill empty points (default 0.0).
319
321 Often you have a text file with a list of comma separated XYZ values to
322 work with (so called CSV file). You can easily use that kind of data
323 source in gdal_grid. All you need is create a virtual dataset header
324 (VRT) for you CSV file and use it as input datasource for gdal_grid.
325 You can find details on VRT format at Virtual Format description page.
326 Here is a small example. Let we have a CSV file called dem.csv
328 containing
329 Easting,Northing,Elevation
331 86943.4,891957,139.13
332 87124.3,892075,135.01
333 86962.4,892321,182.04
334 87077.6,891995,135.01
335 For above data we will create dem.vrt header with the following
337 content:
338 <OGRVRTDataSource>
340 <OGRVRTLayer name="dem">
341 <SrcDataSource>dem.csv</SrcDataSource>
342 <GeometryType>wkbPoint</GeometryType>
343 <GeometryField encoding="PointFromColumns" x="Easting" y="Northing" z="Elevation"/>
344 </OGRVRTLayer>
345 </OGRVRTDataSource>
346 This description specifies so called 2.5D geometry with three
348 coordinates X, Y and Z. Z value will be used for interpolation. Now you
349 can use dem.vrt with all OGR programs (start with ogrinfo to test that
350 everything works fine). The datasource will contain single layer called
351 'dem' filled with point features constructed from values in CSV file.
352 Using this technique you can handle CSV files with more than three
353 columns, switch columns, etc.
354 If your CSV file does not contain column headers then it can be handled
356 in the following way:
357 <GeometryField encoding="PointFromColumns" x="field_1" y="field_2" z="field_3"/>
359 Comma Separated Value description page contains details on CSV format
361 supported by GDAL/OGR.
362
364 Starting with GDAL 2.1, this utility is also callable from C with
365 GDALGrid().
366
368 The following would create raster TIFF file from VRT datasource
369 described in READING COMMA SEPARATED VALUES section using the inverse
370 distance to a power method. Values to interpolate will be read from Z
371 value of geometry record.
372 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
374 The next command does the same thing as the previous one, but reads
376 values to interpolate from the attribute field specified with -zfield
377 option instead of geometry record. So in this case X and Y coordinates
378 are being taken from geometry and Z is being taken from the 'Elevation'
379 field. The GDAL_NUM_THREADS is also set to parallelize the computation.
380 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
382
384 Andrey Kiselev dron@ak4719.spb.edu
385GDAL Thu Jul 25 2019 gdal_grid(1)