= The `gdal_merge` utility =
  ''A python script to mosaic a set of images''
  ''The official documentation for gdal_merge is at http://www.gdal.org/gdal_merge.html.''

gdal_merge.py uses nearest neighbour resampling.  If you want control over the resampling used, you should use gdalwarp instead. 

== Are there other ways of getting a list of images into gdal_merge without putting them all on the command line? ==

Method 1, use `--optfile` flag to specify a text file of a directory listing of each file to merge. 

It can be created in Windows by typing:
{{{
 `dir /b /s *.tif > tiff_list.txtt`
}}}
or on unix by typing:
{{{
ls -1 *.tif > tiff_list.txt
}}}

Then you summon gdal_merge like:
{{{
python gdal_merge.py -n 0 -v -o mosaic_31.tif --optfile tiff_list.txt
}}}

Method 2, use a batch file wrapper, see attached. (for windows)

== Create an RGB image by merging 3 different greyscale bands ==

Conduct "merging by stacking" with the -separate flag.  So if you had three greyscale files that cover the same area and you do:
{{{
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.