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At airports and train stations, passengers line up for face scans at gates and by officers.

On the streets, cameras scan pedestrians and flag vehicles breaking traffic rules.

By law, anyone registering new SIM cards in China must show themselves to a face scanning camera, the images stored in telecom databases. And until recently, Chinese authorities required most guests to scan their faces when checking in to a hotel.

For many, such technology has offered convenience and safety, seamlessly woven into the backdrop of their lives. But for some, it's become an intrusive form of state control.

Associated Press investigations have found that such surveillance systems in China were to a large degree , playing a far greater role in enabling human rights abuses than previously known. It has cemented the rule of China's ruling Communist Party, offering it a powerful tool to control and monitor perceived threats to the state like dissidents, ethnic minorities and even its own officials.

Dozens who spoke to AP, from Tibetan activists to ordinary farmers to , described being tracked and monitored by vast networks of cameras that stud the country, hampering their movements and alerting the police to their activities.

For years, such technology faced legal barriers in the country where it was first developed, the United States. But over the past five years, the U.S. Border Patrol has vastly expanded its surveillance powers, , AP found.

Under the Trump administration, billions are now being poured into a vast array of surveillance systems, including license plate readers across the U.S. that have ensnared innocent drivers for little more than taking a quick trip to areas near the border.

In this series of photographs, an infrared filter was used on a modified camera converted to capture the full spectrum of light, including ultraviolet, visible, and infrared.

This filter, which cuts out some visible light to better reveal infrared, is red by design in order to block certain light wavelengths.

AP photographers on three continents snapped photos showing how these beams are used to track vehicles and people, enable facial recognition - and ultimately, digital control.

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This is a documentary photo story curated by AP photo editors.