The Chinese gov blocks all Google and Bing Maps so citizens can use them for naughty things. So if you are China, you probably have no access or any clue the glories of exploring satellite or aerial images of your home town.
So what does the state do to give its citizens that service, but at the same time controlling 100% of the stuff they can see?
Easy, they draw it all
Baidu maps has a 3d view that is 100% generated on computer. If they don't want you to see "military prison A" they just leave it out, or replace it with a hole.