gdalbuildvrt

Create virtual mosaic

$ gdalbuildvrt [output.vrt] [input1.tif] [input2.tif]

$ gdalbuildvrt -input_file_list [files.txt] [output.vrt]

$ gdalbuildvrt -resolution [average] [output.vrt] [*.tif]

$ gdalbuildvrt -overwrite [output.vrt] [*.tif]

$ gdalbuildvrt -b [1] -b [2] -b [3] [output.vrt] [input.tif]

gdalbuildvrt [options] output.vrt inputs...

gdalbuildvrt creates a virtual raster dataset (VRT) that references multiple input files without copying data. VRT files are XML documents describing how to combine source rasters into a unified dataset, enabling on-the-fly mosaicking, stacking, and subsetting.
The tool can mosaic adjacent tiles into seamless coverages or stack bands from separate files into multi-band datasets. Resolution handling controls how inputs with different pixel sizes are combined. VRTs support mixing projections with appropriate flags.
Virtual datasets save disk space and processing time compared to creating physical mosaics. They're ideal for working with large tile collections, time series data, and multi-spectral imagery where logical combinations change frequently.

-input_file_list file

Read inputs from file.

Resolution calculation (highest, lowest, average, user).

Overwrite existing output.

Select specific band.

Put each input in separate band.

Allow different projections.

Target extent.

gdaladdo(1), gdal_translate(1)