There are 170 million surveillance cameras in China. By 2020, the country hopes to have 570 million — that's nearly one camera for every two citizens.

At the same time, China is a building a national database that will recognize any citizen withinthree seconds. Though that system probably won't be unveiled for a number of years, facial recognition is widespread in China.

Thanks to a large sample population and lax privacy laws, police and private companies have led the way in developing surveillance technology that is now being used to track travel, shopping, crime, and even toilet paper usage.

Take a look at all the ways people's faces are being used for surveillance — with and without their permission.