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I have scripted a workflow in ArcGIS Pro where a set of rasters gets some new data for certain areas, which is updated by building a Mosaic Dataset where the new rasters are layed on top of the old ones (Z-Order). Then I perform clips on this Mosaic Dataset to get the updated tiles in the wanted format.

My task is to do the same in QGIS. In ArcGIS, the whole point of using Mosaic Datasets is not to copy the raster files, but reference them instead.

I understand that GDAL virtual rasters also reference the file locations. But is it possible to put new rasters on top of the old ones, and then clip the virtual raster, or am I right with my assumption that virtual rasters do not have any functionalities other then being a catalog of image file paths?

This is related to ArcGIS Raster Mosaic Dataset and GDAL VRT, when to use?

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    What have you tried so far? Have you done any testing or research yourself? See gis.stackexchange.com/help/how-to-ask for tips on asking questions. The GDAL buildvrt documentation says "If there is some amount of spatial overlapping between files, the order of files appearing in the list of source matter: files that are listed at the end are the ones from which the content will be fetched." Commented May 7, 2023 at 12:04
  • with SAGA mosaicking, I do get the last image in the list on top of the others. With Build VRT, it does not apper, strangelz, when I insert it as the first item in the input paths list, it only appears in the vrt, without the others. Commented May 9, 2023 at 10:17

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I have managed to write a script that works completely with vrt. VRTs are clipped and referenced again in another vrt. It processes quite fast, actually much quicker than my script with Mosaic Datasets in ArcGIS Pro. What takes a long time is the visualization of the vrt in QGIS, but as the end product of interests are TIFs, that should not be a bi problem. One problem I was facing was that I was testing which image was on top using images with differing number of bands. That did not work, and also mixing TIFs and VRTs into one VRT does not seem to work.

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