Can I create a virtual mosaic using other virtual mosaics?

Question

I am following this example - http://linfiniti.com/2009/09/image-mosaicking-with-gdal/

I have 6TB of aerial imagery in 6 folders 1TB each and each folder has many subdirectories including the geotiffs. I am using gdal_translate to compress the data first. Then I use gdalbuildvrt to create the mosaics, and finally I build the pyramids/overviews for the mosaics using gdaladdo.

My target is to use geoserver to serve all the aerial data connected together. My concern is that a subdirectory may be 100GB which takes quite a while to process (either compress or building pyramids). This is why I did not use gdal on all 6TB at once and preferred handling them in different directories. Thus, my question is whether or not I will be able to use something like gdal_merge to connect all the pyramitised mosaics together to a bigger mosaic and serve it using geoserver or similar OS software.

Apologies for the huge post! Thanks in advance for any hints or tips.

Answer 1

Answering the title, yes a vrt can reference other vrt's. It's a convenient method to do things like extract a subset of the whole for a project specific analysis, use different nodata values or masks from the source, specify different pixel size, combine image bands in different orders, rescale the pixel values, and so on.

For your case, assembling a mosaic of mosaics, just feed the existing vrt's to gdalbuildvrt:

gdalbuildvrt final_mosaic.vrt tiles\*.vrt