mosaics a set of images
gdal_merge.py [-o out_filename] [-of out_format] [-co NAME=VALUE]* [-ps pixelsize_x pixelsize_y] [-tap] [-separate] [-v] [-pct] [-ul_lr ulx uly lrx lry] [-n nodata_value] [-init "value [value...]"] [-ot datatype] [-createonly] input_files
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.
Pixel size to be used for the output file. If not specified the resolution of the first input file will be used.
(GDAL >= 1.8.0) (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.
NOTE: gdal_merge.py is a Python script, and will only work if GDAL was built with Python support.
Create an image with the pixels in all bands initialized to 255.
% gdal_merge.py -init 255 -o out.tif in1.tif in2.tif
Create 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 initalized to 255.
% gdal_merge.py -init "0 0 255" -o out.tif in1.tif in2.tif