LONDON - From speeding up boarding at airports to boosting security at malls and concerts, facial recognition technology has become increasingly pervasive, raising concerns about privacy.
Britain's data protection watchdog said this week it was looking into use of the technology after reports that a property developer had set up facial recognition cameras in London's central King's Cross area.
Computers have become adept at identifying people by matching a scan of their facial features against a photograph, but critics say the technology is still prone to errors and could lead to excessive surveillance.
Here are eight other world locations with facial recognition technology.
In July, the airport in the southern Indian tech hub of Bengaluru launched a "paperless biometric technology" system that uses facial recognition to identify passengers checking in.
Another airport in the southern Indian city of Hyderabad was also testing the technology.
NO. 11 MIDDLE SCHOOL, HANGZHOU
A high school in the Chinese city of Hangzhou last year installed cameras with facial recognition tools that capture students' expressions and movements to ensure they pay attention in class. The Hangzhou No. 11 Middle School's "smart classroom behaviour management system" detected whether students were reading, listening or napping at their desks - feeding the information to the teacher in real time.
FLYZOO HOTEL, HANGZHOU
Guests at the futuristic FlyZoo hotel in Hangzhou check in by scanning their faces as well as passports or other ID at podiums in the lobby.
Elevators scan guests' faces again to verify which floor they can access and hotel room doors are opened with another face scan. Facial recognition cameras automatically add charges from the hotel's bar and restaurant to the room rate.
The hotel, owned by Chinese internet giant Alibaba, opened last year.
TOKYO 2020 OLYMPICS
Tokyo 2020 will be the first Olympics to use facial recognition technology to increase security around all venues, the organisers announced last year.
More than 300,000 athletes and Games staff will have to submit photographs to a database before the Olympics start in July next year.
WINTER WONDERLAND, CARDIFF
In 2017, South Wales police became the first British force to deploy cameras equipped with facial recognition software to scan passers-by in public spaces and compare them to watchlists of people being sought by police.
It has since used the technology during a number of high-profile events, including concerts and rugby matches.
The trial has prompted a legal challenge over concerns police is violating citizens' rights by recording their faces without consent or any grounds for suspecting they have committed a crime.
TAYLOR SWIFT CONCERTS
U.S. singer Taylor Swift used facial recognition cameras to enhance her own security during a 2018 tour, according to Rolling Stone magazine.
It said kiosks played videos of the star and would simultaneously photograph the viewers to check their images against a database of known stalkers.
CHANGI AIRPORT, SINGAPORE
Singapore's Changi airport uses facial recognition technology to offer self-service options at check-in, bag drop, immigration and boarding at its newest terminal.
Last year the airport said it was also considering using facial recognition systems to find late passengers.
The U.S. Customs and Border Protection (CBP) agency has been using facial recognition systems at dozens of airports and ports around the country to verify the identity of travellers entering and exiting the country.
Run in partnership with air and cruise lines the pilot program aims to enhance security and speed up custom controls but has drawn criticism from human rights groups.
(Sources: Changi airport, CBP, South Wales police)