# gdalwarp

Image reprojection and warping utility

## Synopsis

    gdalwarp [--help-general] [--formats]
        [-s_srs srs_def] [-t_srs srs_def] [-ct string] [-to "NAME=VALUE"]* [-vshift | -novshift]
        [[-s_coord_epoch epoch] | [-t_coord_epoch epoch]]
        [-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]
        [-if format]* [-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. If not specified the SRS found in the input dataset will be used.

  The coordinate reference systems that can be passed are anything supported by the OGRSpatialReference.SetFromUserInput() call, which includes EPSG Projected, Geographic or Compound CRS (i.e. EPSG:4296), a well known text (WKT) CRS definition, PROJ.4 declarations, or the name of a .prj file containing a WKT CRS definition.

  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.

-s_coord_epoch <epoch>

  New in version 3.4.

  Assign a coordinate epoch, linked with the source SRS. Useful when the source SRS is a dynamic CRS. Only taken into account if `-s_srs` is used.

  Currently `-s_coord_epoch` and `-t_coord_epoch` are mutually exclusive, due to lack of support for transformations between two dynamic CRS.

-t_srs <srs_def>

  Set target spatial reference.

  A source SRS must be available for reprojection to occur. The source SRS will be by default the one found in the input dataset when it is available, or as overridden by the user with `-s_srs`

  The coordinate reference systems that can be passed are anything supported by the OGRSpatialReference.SetFromUserInput() call, which includes EPSG Projected, Geographic or Compound CRS (i.e. EPSG:4296), a well known text (WKT) CRS definition, PROJ.4 declarations, or the name of a .prj file containing a WKT CRS definition.

  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_coord_epoch <epoch>

  New in version 3.4.

  Assign a coordinate epoch, linked with the target SRS. Useful when the target SRS is a dynamic CRS. Only taken into account if `-t_srs` is used.

  Currently `-s_coord_epoch` and `-t_coord_epoch` are mutually exclusive, due to lack of support for transformations between two dynamic CRS.

-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()`. See `GDALCreateRPCTransformerV2()` for RPC specific options.

-vshift

  Force the use of vertical shift. This option is generally not necessary, except when using an explicit coordinate transformation (`-ct`), and not specifying an explicit source and target SRS.

  New in version 3.4.

-novshift

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

  Note

  this option was named `-novshiftgrid` in GDAL 2.2 to 3.3.

  New in version 3.4.

-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 transformer 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>

  Set output file resolution (in target georeferenced units).

  If not specified (or not deduced from -te and -ts), gdalwarp will generate an output raster with xres=yres, and that even when using gdalwarp in scenarios not involving reprojection.

-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. Alignment means that xmin / resx, ymin / resy, xmax / resx and ymax / resy are integer values.

-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 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`.

-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 weighted average of all non-NODATA contributing pixels.

  `rms` root mean square / quadratic mean of all non-NODATA contributing pixels (GDAL >= 3.3)

  `mode`: mode resampling, selects the value which appears most often of all the sampled points. In the case of ties, the first value identified as the mode will be selected.

  `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.

  `sum`: compute the weighted sum of all non-NODATA contributing pixels (since GDAL 3.1)

  Note

  When downsampling is performed (use of `-tr` or `-ts`), existing overviews (either internal/implicit or external ones) on the source image will be used by default by selecting the closest overview to the desired output resolution. The resampling method used to create those overviews is generally not the one you specify through the `-r` option. Some formats, like JPEG2000, can contain significant outliers due to wavelet compression works. It might thus be useful in those situations to use the `-ovr` `NONE` option to prevent existing overviews to be used.

-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.

  When this option is set to a non-`None` value, it causes the `UNIFIED_SRC_NODATA` warping option (see `GDALWarpOptions::papszWarpOptions`) to be set to `YES`, if it is not explicitly set.

  If `-srcnodata` is not explicitly set, but the source dataset has nodata values, they will be taken into account, with `UNIFIED_SRC_NODATA` at `PARTIAL` by default.

-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.

-if <format>

  Format/driver name to be attempted to open the input file(s). It is generally not necessary to specify it, but it can be used to skip automatic driver detection, when it fails to select the appropriate driver. This option can be repeated several times to specify several candidate drivers.

  New in version 3.2.

-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. Overwriting must be understood here as deleting and recreating the file from scratch. Note that if this option is not specified and the output file already exists, it will be updated in place.

-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.

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

## See also

Wiki page discussing options and behaviours of gdalwarp