I am wondering how I can make a band composite from three large bands files from Landsat? I was using option Raster>Miscellaneous>Merge but when I try to do it it crashes.
This is something you can achieve with a Virtual Raster (Catalog). This will create a metadata file (.vrt) that QGIS treats like a merged multi-band raster without having to merge all the bands.
- Raster --> Misc. --> Build Virtual Raster
- Select the bands you want to use as "Input files"
- Check "Separate" to put each input file into a single band (otherwise they will be merged spatially and all put into a single band)
- Open the Virtual Raster (.vrt) in QGIS and treat it like a merged composite
Here is an example using a Landsat 8 scene of the Alps to create a band 7,5,2 false color composite. Creation of the Virtual Raster (urban-fcc.vrt) takes seconds and the file is 3KB in size.