[Restorer]

Since highly detailed USGS maps are available at low cost, I don't see how this makes much difference. High-res satellite photos are available on the Internet. All this info is probably in the public domain, anyway.

No offense, but Coffee County is probably not on the priority target list for China (or anybody else). Their missiles won't reach TN, anyway.

[Brian Mosely]

Our official don't think so...for one, we have AEDC here...a huge security concren. GIS is a whole lot more detailed than topograhpic maps. It is suppose to have everything included in them: gas lines, power, water...you name it.

[Amerigomag]

Given that every thing you say is correct don't we at least have to start somewhere?

[rokkhound]

I agree with this. GIS databases are on the internet for many, many counties across the country. Not all have aerial imagery, but you'd be amazed at the information in the public domain. Nothing new here.

[snopercod]

Since highly detailed USGS maps are available at low cost, I don't see how this makes much difference.

It makes a lot of difference altitude wise. The GPS constellation are in circular orbits, which each satellite "knows" exactly. But the shape of the earth varies substantially from a sphere - even an elipsoid. That's why your civilian GPS can be off as much as 500' in altitude depending on where you are holding it.

The information describing the exact shape of the earth - the kind needed to target a cruise missile - is classified either Secret or Top Secret, not sure which.