I used this script to generate a few buildings that I was hoping to import into UDK. Each building is made of about 1000 separate objects. When I export a building as FBX and import the file into UDK it breaks it up into its individual objects again, so I was wondering how I would avoid this. Whether there was a tool to combine all of the objects into one mesh automatically before exporting or if I could prevent UDK from breaking them upon import.
One way would be to have one building in your scene visible (hide everything else)
Then convert one of the pieces into an editable poly - then click the box next to add, and pick all the pieces in the box. This will make one editable poly.
I would recommend removing the xform and placing the pivot to the base of the building to help with importing.
BUT this method will not remove the inner poly's of all the buildings, for that you would need to edit all the objects individually and stitch them together. I think it would be quicker to build them from scratch, but use the buildings you generated as reference.
The inner poly's will vastly increase the total polycount of each building and will generally be a waste of memory. So it would be better to optimize in the long run.