Having Georeferenced images is great, but what if you have multiple GeoTiffs covering a large plot of land? Raster Merging makes file management easier by combining a series of GeoTiffs into one!
1. In the QGIS Browser Panel, select the GeoTiffs you want to merge and right click to add them to the main window.
2. Select Raster > Miscellaneous > Merge
3. In the Merge dialogue window, for Input files, browse to your directory containing your GeoTiff tiles. Select them all by holding Ctrl + select (Shift + select on a mac). For Output files, name your output file with the specified format of .tif for a georeferenced merged raster.
4. Select "Creation Options" checkbox, and in the Profile drop down menu, select your compression level. We recommend any form of lossless compression (note: we do NOT recommend jpeg compression for GeoTiff merge export).
"When we first merged two GeoTiffs of 5.24GB and 8.55GB without any compression, it generated a 24GB file! Use compression to save Hard Disk space."
5. Select OK, let it do its thing. Merging takes a long time (depends on the size of the project), be patient and trust the process. It took us 2.5 hours to complete are first merge on a late 2013 iMac.