Already read Merge Multi-Band Geotiff with different datatypes (with gdal) but can't apply that solution so please do not flag as duplicate.

I have near 3.000 geotiff files that I need to merge into just one.

this is what I done so far:

gdalbuildvrt -input_file_list list_of_files.txt -overwrite -addalpha images.vrt

and then

gdal_translate -tr 0.000170 0.000170 -r cubicspline -of GTiff images.vrt test.tif

I've got this warning:

Warning 1: Unable to export GeoTIFF file with different datatypes per different bands. All bands should have the same types in TIFF.

I can get rid of the warning when remove -addalpha from gdalbuildvrt.

I'm a complete newbie on this so I ask: What is the implication of the -addalpha parameter and that warning if I choose to keep it?


From docs:

-addalpha: Adds an alpha mask band to the VRT [...] The alpha band is filled on-the-fly with the value 0 in areas without any source raster, and with value 255 in areas with source raster

The alpha channel is added as a Band of type byte, while the rest of your files are probably a different Type (e.g. UINT16). Like that you cannot combine them in one GeoTiff.

Best option would be to create a mask from the alpha channel.

When you have an RGB image:

gdal_translate -tr 0.000170 0.000170 -r cubicspline -b 1 -b 2 -b 3 -mask 4 -of GTiff images.vrt test.tif

When you have a Single-band image:

gdal_translate -tr 0.000170 0.000170 -r cubicspline -b 1 -mask 2 -of GTiff images.vrt test.tif

If you don't know the band numbers, find out after creating the VRT with this command:

gdalinfo images.vrt

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