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.

Specify overlap precedence

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

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