Commercial satellite imagery doesn't have to be filtered at all. Images of 'an airfield in the Nevada desert somewhere near Las Vegas' were available commercially even while official US images of the same were fully redacted! And remember the hoo-hah about Google Earth images of US bases in Iraq, helping those who wanted to plan attacks? There was no way of stopping those, save asking very nicely...
Last edited by Easy Street; 10th Jan 2013 at 23:44.