Now you can take the pictures that @hushush drew and reflect them to make the fourth view, so in reality, you should only need 2 images to be able to turn a building all four ways. The only downside that I see to this would be if bast decided to make light-up night versions of a building that could be turned four ways, because he would need four images for each building then, and that would take a very long time to do every single building.