 Hello, in this video we are going to mosaic dm tiles, here you see the dm tiles that we have downloaded and it's clearly visible that these are tiles, there are two ways to mosaic them, there is the merge tool where you can create a geotiff, simply go to merge and then select the tiles that you want to merge, we keep all the defaults and then define an output file name, this will create one big file as a geotiff from all the tiles, there's a more efficient way if the mosaic is just an intermediate result, then you can use the build virtual ruster method, the dialog is almost the same, so you select the tiles that you want to merge, keep place each input file in separate band unchecked, you only check that box if you want to stack them like with remote sensing channels, bands, there's an output file name we get the .vrt file indicating that's a virtual file, it's just a very small file that links everything together and the advantage is that you can further process the vrt file as if it was a real file but you don't have the overhead of having big data on your hard disk, on this video you've learned about two methods to merge or mosaic dm tiles, merging it into a geotiff and merging it in a vrt virtual file which is more efficient if you have intermediate results