# gdalwarp¶

Image reprojection and warping utility

## Synopsis¶

gdalwarp [--help-general] [--formats]
[-s_srs srs_def] [-t_srs srs_def] [-ct string] [-to "NAME=VALUE"]* [-novshiftgrid]
[-order n | -tps | -rpc | -geoloc] [-et err_threshold]
[-refine_gcps tolerance [minimum_gcps]]
[-te xmin ymin xmax ymax] [-te_srs srs_def]
[-tr xres yres] [-tap] [-ts width height]
[-ovr level|AUTO|AUTO-n|NONE] [-wo "NAME=VALUE"] [-ot Byte/Int16/...] [-wt Byte/Int16]
[-srcnodata "value [value...]"] [-dstnodata "value [value...]"]
[-srcalpha|-nosrcalpha] [-dstalpha]
[-r resampling_method] [-wm memory_in_mb] [-multi] [-q]
[-cutline datasource] [-cl layer] [-cwhere expression]
[-csql statement] [-cblend dist_in_pixels] [-crop_to_cutline]
[-of format] [-co "NAME=VALUE"]* [-overwrite]
[-nomd] [-cvmd meta_conflict_value] [-setci] [-oo NAME=VALUE]*
[-doo NAME=VALUE]*
srcfile* dstfile


## Description¶

The gdalwarp utility is an image mosaicing, reprojection and warping utility. The program can reproject to any supported projection, and can also apply GCPs stored with the image if the image is “raw” with control information.

-s_srs <srs def>

Set source spatial reference.

The coordinate systems that can be passed are anything supported by the OGRSpatialReference.SetFromUserInput() call, which includes EPSG PCS and GCSes (i.e. EPSG:4296), PROJ.4 declarations (as above), or the name of a .prj file containing well known text. Starting with GDAL 2.2, if the SRS has an explicit vertical datum that points to a PROJ.4 geoidgrids, and the input dataset is a single band dataset, a vertical correction will be applied to the values of the dataset.

-t_srs <srs_def>

Set target spatial reference.

The coordinate systems that can be passed are anything supported by the OGRSpatialReference.SetFromUserInput() call, which includes EPSG PCS and GCSes (i.e. EPSG:4296), PROJ.4 declarations (as above), or the name of a .prj file containing well known text. Starting with GDAL 2.2, if the SRS has an explicit vertical datum that points to a PROJ.4 geoidgrids, and the input dataset is a single band dataset, a vertical correction will be applied to the values of the dataset.

-ct <string>

A PROJ string (single step operation or multiple step string starting with +proj=pipeline), a WKT2 string describing a CoordinateOperation, or a urn:ogc:def:coordinateOperation:EPSG::XXXX URN overriding the default transformation from the source to the target CRS. It must take into account the axis order of the source and target CRS.

New in version 3.0.

-to <NAME=VALUE>

Set a transformer option suitable to pass to GDALCreateGenImgProjTransformer2().

-novshiftgrid

Disable the use of vertical datum shift grids when one of the source or target SRS has an explicit vertical datum, and the input dataset is a single band dataset.

New in version 2.2.

-order <n>

order of polynomial used for warping (1 to 3). The default is to select a polynomial order based on the number of GCPs.

-tps

Force use of thin plate spline transformer based on available GCPs.

-rpc

Force use of RPCs.

-geoloc

Force use of Geolocation Arrays.

-et <err_threshold>

Error threshold for transformation approximation (in pixel units - defaults to 0.125, unless, starting with GDAL 2.1, the RPC_DEM warping option is specified, in which case, an exact transformer, i.e. err_threshold=0, will be used).

-refine_gcps <tolerance minimum_gcps>

Refines the GCPs by automatically eliminating outliers. Outliers will be eliminated until minimum_gcps are left or when no outliers can be detected. The tolerance is passed to adjust when a GCP will be eliminated. Not that GCP refinement only works with polynomial interpolation. The tolerance is in pixel units if no projection is available, otherwise it is in SRS units. If minimum_gcps is not provided, the minimum GCPs according to the polynomial model is used.

-te <xmin ymin xmax ymax>

Set georeferenced extents of output file to be created (in target SRS by default, or in the SRS specified with -te_srs)

-te_srs <srs_def>

Specifies the SRS in which to interpret the coordinates given with -te. The <srs_def> may be any of the usual GDAL/OGR forms, complete WKT, PROJ.4, EPSG:n or a file containing the WKT. This must not be confused with -t_srs which is the target SRS of the output dataset. -te_srs is a convenience e.g. when knowing the output coordinates in a geodetic long/lat SRS, but still wanting a result in a projected coordinate system.

-tr <xres> <yres>

Sse output file resolution (in target georeferenced units)

-tap

(target aligned pixels) align the coordinates of the extent of the output file to the values of the -tr, such that the aligned extent includes the minimum extent.

-ts <width> <height>

Set output file size in pixels and lines. If width or height is set to 0, the other dimension will be guessed from the computed resolution. Note that -ts cannot be used with -tr

-ovr <level|AUTO|AUTO-n|NONE>

To specify which overview level of source files must be used. The default choice, AUTO, will select the overview level whose resolution is the closest to the target resolution. Specify an integer value (0-based, i.e. 0=1st overview level) to select a particular level. Specify AUTO-n where n is an integer greater or equal to 1, to select an overview level below the AUTO one. Or specify NONE to force the base resolution to be used (can be useful if overviews have been generated with a low quality resampling method, and the warping is done using a higher quality resampling method).

-wo "NAME=VALUE"

Set a warp option. The GDALWarpOptions::papszWarpOptions docs show all options. Multiple -wo options may be listed.

-ot <type>

Force the output image bands to have a specific type. Use type names (i.e. Byte, Int16,…)

-wt <type>

Working pixel data type. The data type of pixels in the source image and destination image buffers.

-r <resampling_method>

Resampling method to use. Available methods are:

near: nearest neighbour resampling (default, fastest algorithm, worst interpolation quality).

bilinear: bilinear resampling.

cubic: cubic resampling.

cubicspline: cubic spline resampling.

lanczos: Lanczos windowed sinc resampling.

average: average resampling, computes the average of all non-NODATA contributing pixels.

mode: mode resampling, selects the value which appears most often of all the sampled points.

max: maximum resampling, selects the maximum value from all non-NODATA contributing pixels.

min: minimum resampling, selects the minimum value from all non-NODATA contributing pixels.

med: median resampling, selects the median value of all non-NODATA contributing pixels.

q1: first quartile resampling, selects the first quartile value of all non-NODATA contributing pixels.

q3: third quartile resampling, selects the third quartile value of all non-NODATA contributing pixels.

-srcnodata <value [value...]>

Set nodata masking values for input bands (different values can be supplied for each band). If more than one value is supplied all values should be quoted to keep them together as a single operating system argument. Masked values will not be used in interpolation. Use a value of None to ignore intrinsic nodata settings on the source dataset.

-dstnodata <value [value...]>

Set nodata values for output bands (different values can be supplied for each band). If more than one value is supplied all values should be quoted to keep them together as a single operating system argument. New files will be initialized to this value and if possible the nodata value will be recorded in the output file. Use a value of None to ensure that nodata is not defined. If this argument is not used then nodata values will be copied from the source dataset.

-srcalpha

Force the last band of a source image to be considered as a source alpha band.

-nosrcalpha

Prevent the alpha band of a source image to be considered as such (it will be warped as a regular band)

New in version 2.2.

-dstalpha

Create an output alpha band to identify nodata (unset/transparent) pixels.

-wm <memory_in_mb>

Set the amount of memory that the warp API is allowed to use for caching. The value is interpreted as being in megabytes if the value is less than 10000. For values >=10000, this is interpreted as bytes.

-multi

Use multithreaded warping implementation. Two threads will be used to process chunks of image and perform input/output operation simultaneously. Note that computation is not multithreaded itself. To do that, you can use the -wo NUM_THREADS=val/ALL_CPUS option, which can be combined with -multi

-q

Be quiet.

-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.

-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.

-cutline <datasource>

Enable use of a blend cutline from the name OGR support datasource.

-cl <layername>

Select the named layer from the cutline datasource.

-cwhere <expression>

Restrict desired cutline features based on attribute query.

-csql <query>

Select cutline features using an SQL query instead of from a layer with -cl.

-cblend <distance>

Set a blend distance to use to blend over cutlines (in pixels).

-crop_to_cutline

Crop the extent of the target dataset to the extent of the cutline.

-overwrite

Overwrite the target dataset if it already exists.

-nomd

Do not copy metadata. Without this option, dataset and band metadata (as well as some band information) will be copied from the first source dataset. Items that differ between source datasets will be set to * (see -cvmd option).

-cvmd <meta_conflict_value>

Value to set metadata items that conflict between source datasets (default is “*”). Use “” to remove conflicting items.

-setci

Set the color interpretation of the bands of the target dataset from the source dataset.

-oo <NAME=VALUE>

Dataset open option (format specific)

-doo <NAME=VALUE>

Output dataset open option (format specific)

New in version 2.1.

<srcfile>

The source file name(s).

<dstfile>

The destination file name.

Mosaicing into an existing output file is supported if the output file already exists. The spatial extent of the existing file will not be modified to accommodate new data, so you may have to remove it in that case, or use the -overwrite option.

Polygon cutlines may be used as a mask to restrict the area of the destination file that may be updated, including blending. If the OGR layer containing the cutline features has no explicit SRS, the cutline features must be in the SRS of the destination file. When writing to a not yet existing target dataset, its extent will be the one of the original raster unless -te or -crop_to_cutline are specified.

When doing vertical shift adjustments, the transformer option -to ERROR_ON_MISSING_VERT_SHIFT=YES can be used to error out as soon as a vertical shift value is missing (instead of 0 being used).

Starting with GDAL 3.1, it is possible to use as output format a driver that only supports the CreateCopy operation. This may internally imply creation of a temporary file.

## Examples¶

• Basic transformation:

gdalwarp -t_srs EPSG:4326 input.tif output.tif

• For instance, an eight bit spot scene stored in GeoTIFF with control points mapping the corners to lat/long could be warped to a UTM projection with a command like this:

gdalwarp -t_srs '+proj=utm +zone=11 +datum=WGS84' -overwrite raw_spot.tif utm11.tif

• For instance, the second channel of an ASTER image stored in HDF with control points mapping the corners to lat/long could be warped to a UTM projection with a command like this:

New in version 2.2.

gdalwarp -overwrite HDF4_SDS:ASTER_L1B:"pg-PR1B0000-2002031402_100_001":2 pg-PR1B0000-2002031402_100_001_2.tif

• To apply a cutline on a un-georeferenced image and clip from pixel (220,60) to pixel (1160,690):

gdalwarp -overwrite -to SRC_METHOD=NO_GEOTRANSFORM -to DST_METHOD=NO_GEOTRANSFORM -te 220 60 1160 690 -cutline cutline.csv in.png out.tif


where cutline.csv content is like:

id,WKT
1,"POLYGON((....))"

• To transform a DEM from geoid elevations (using EGM96) to WGS84 ellipsoidal heights:

New in version 2.2.

gdalwarp -overwrite in_dem.tif out_dem.tif -s_srs EPSG:4326+5773 -t_srs EPSG:4979