With the recent hubbub over domestic syping by U.S. spy agencies, here's an example that's probably legal.
The article is about the National Geospatial-Intelligence Agency.
Their work is described this way:
Geospatial intelligence is the science of combining imagery, such as satellite pictures, to physically depict features or activities happening anywhere on the planet. A part of the Defense Department, the NGA usually operates unnoticed to provide information on nuclear sites, terror camps, troop movements or natural disasters.
With help, the agency can also zoom in. Its officials cooperate with private groups, such as hotel security, to get access to footage of a lobby or ballroom. That video can then be linked with mapping and graphical data to help secure events or take action, if a hostage situation or other catastrophe happens.
Privacy advocates wonder how much the agency picks up — and stores. Many are increasingly skeptical of intelligence agencies with recent revelations about the Bush administration's surveillance on phone calls and e-mails.
Among the government's most closely guarded secrets, the quality of pictures NGA receives from classified satellites is believed to far exceed the one-meter resolution available commercially. That means they can take a satellite "snapshot" from high above the atmosphere that is crisply detailed down to one meter level, which is 3.3 feet.
In other words their job is similar to the Google Earth service. But it's likely that, because they're the military, the resolution on their images is much better.
The images available through commercial services are, by law, limited to a resolution of 1 meter. Meaning the smallest object that can be identified is 1 meter in size. So we wonder what their resolution is. For example if you have a habit of having sex in the back yard, the commercial images won't recognize what you're doing, but what about theirs?
The article raises a big question. Just what are they doing spending most of their effort looking inside the U.S. territory? What are they looking for? An obvious use leaps to mind, that this service could help locate marijuana fields and the like. It might also help locate illicit airfields, such as used by drug smugglers.
I expect one strategic service they provide is finding new construction. This would require some fancy image analysis, but with a whole world full of images detecting new construction would be very labor intensive. However a computer, with fancy image analysis, might be able to identify changes between pictures taken at different times. The tricky part of course is the pictures will never be at the same angle or lighting conditions, hence the required fancy image analysis.
My thought is that if "change" is detected in a series of pictures, then a flag could be raised to send those pictures to an analyst for further study. It may be benign, but it may be an illicit nuclear weapons construction facility.
In any case the current hubbub is over domestic spying. Earlier in this I suggested this is probably legal. My reasoning is pictures taken of the outdoors are, by definition, public spaces. A warrant is not required for anybody to take a picture of the outside of a building, nor is one required to take a picture from above. That's all they're doing.
Where it becomes a little tricky is they have made arrangements with building owners to incorporate video from surveillance cameras. Where are those surveillance cameras pointing? Inside or outside buildings? Are they pointing into private spaces or only public ones?