I have in QGIS a higher quality GeoTIFF overlayed on a larger, lower quality GeoTIFF. I reprojected one raster into the coordinate system of the other.

How can I export these to a single GeoTIFF while retaining the resolution of the high quality raster?

I've tried using the Merge tool (with no data set to 255 to remove whitespace) but get an error at 50%: "Illegal band #." The resulting layer is low quality and much brighter.

I also tried using Build Virtual Raster, but the resulting layer turns red and green (with "Place each input file into separate band" checked). Without it checked, the high quality raster doesn't show up in the new layer.

The high quality raster has 3 bands and the lower quality raster has 4 bands. There is no information by the 4th band though

  • Are both geotiffs the same bit-depth? It sounds like the better quality image gets downsampled both in spectral and spatial resolution. – Gabriel C. Jun 21 '19 at 15:25
  • @GabrielC. I just used Translate to convert both to Float32 but get the same results when using Merge or Build Virtual Raster – Preston Jun 21 '19 at 15:36
  • I now see that the original rasters are both byte data types. – Preston Jun 21 '19 at 15:43
  • The 4th band on the lower quality image is probably an alpha-channel. But have you tried to reorder the images in the VRT creation at the file selection dialog? You can drag the entries so one will be considered on top of the other. – Gabriel C. Jun 21 '19 at 15:50

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