NAME

       gdal_merge - Mosaics a set of images.

SYNOPSIS

          gdal_merge.py [--help] [--help-general]
                        [-o <out_filename>] [-of <out_format>] [-co <NAME>=<VALUE>]...
                        [-ps <pixelsize_x> <pixelsize_y>] [-tap] [-separate] [-q] [-v] [-pct]
                        [-ul_lr <ulx> <uly> <lrx> <lry>] [-init "<value>[ <value>]..."]
                        [-n <nodata_value>] [-a_nodata <output_nodata_value>]
                        [-ot <datatype>] [-createonly] <intput_file> [<intput_file>]...

DESCRIPTION

       This  utility  will  automatically mosaic a set of images.  All the images must be in the same coordinate
       system and have a matching number of bands, but they may be overlapping, and at different resolutions. In
       areas of overlap, the last image will  be  copied  over  earlier  ones.  Nodata/transparency  values  are
       considered  on  a  band  by band level, i.e. a nodata/transparent pixel on one source band will not set a
       nodata/transparent value on all bands for the target pixel in the resulting raster nor will it  overwrite
       a valid pixel value.

       --help Show this help message and exit

       --help-general
              Gives a brief usage message for the generic GDAL commandline options and exit.

       -o <out_filename>
              The  name  of  the  output  file,  which will be created if it does not already exist (defaults to
              "out.tif").

       -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.

       -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, Int8, UInt16, Int16, UInt32, Int32, UInt64, Int64, Float32, Float64,
              CInt16, CInt32, CFloat32 or CFloat64.

       -ps <pixelsize_x> <pixelsize_y>
              Pixel size to be used for the output file.  If not specified the resolution  of  the  first  input
              file will be used.

       -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.

       -ul_lr <ulx> <uly> <lrx> <lry>
              The extents of the output file.  If not specified the aggregate extents of all input files will be
              used.

       -v     Generate verbose output of mosaicing operations as they are done.

       -separate
              Place each input file into a separate band.

       -pct   Grab  a  pseudo-color  table  from  the  first  input  image,  and use it for the output.  Merging
              pseudo-colored images this way assumes that all input files use the same color table.

       -n <nodata_value>
              Ignore pixels from files being merged in with this pixel value.

       -a_nodata <output_nodata_value>
              Assign a specified nodata value to output bands.

       -init <"value(s)">
              Pre-initialize the output image bands with these values.  However, it is not marked as the  nodata
              value in the output file.  If only one value is given, the same value is used in all the bands.

       -createonly
              The  output  file  is  created (and potentially pre-initialized) but no input image data is copied
              into it.

       NOTE:
          gdal_merge.py is a Python script, and will only work if GDAL was built with Python support.

EXAMPLES

   Creating an image with the pixels in all bands initialized to 255
          gdal_merge.py -init 255 -o out.tif in1.tif in2.tif

   Creating an RGB image that shows blue in pixels with no data
       The first two bands will be initialized to 0 and the third band will be initialized to 255.

          gdal_merge.py -init "0 0 255" -o out.tif in1.tif in2.tif

   Passing a large list of files to gdal_merge
       A large list of files can be passed to gdal_merge by listing them in a text file using:

          ls -1 *.tif > tiff_list.txt

       on Linux, or

          dir /b /s *.tif > tiff_list.txt

       on Windows. The text file can then be passed to gdal_merge using --optfile:

          gdal_merge.py -o mosaic.tif --optfile tiff_list.txt

   Creating an RGB image by merging 3 different greyscale bands
       Conduct "merging by stacking" with the -separate flag. Given three greyscale files that  cover  the  same
       area, you can run:

          gdal_merge.py -separate 1.tif 2.tif 3.tif -o rgb.tif

       This maps 1.tif to red, 2.tif to green and 3.tif to blue.

   Specifying overlap precedence
       The  last  image  in the input line comes out on top of the finished image stack.  You might also need to
       use -n to note which value should not be copied into the destination image if it is not  already  defined
       as nodata.

          gdal_merge.py -o merge.tif -n 0 image1.tif image2.tif image3.tif image4.tif

AUTHOR

       Frank Warmerdam <warmerdam@pobox.com>, Silke Reimer <silke@intevation.de>

COPYRIGHT

       1998-2024

                                                  Feb 08, 2024                                     GDAL_MERGE(1)