Variation in faces as they age and with accessories.
A small camera fitted to the glasses can capture 400 facial images per second and send them to a central computer database storing up to 13 million faces.
The system can compare biometric data at 46,000 points on a face and will immediately signal any matches to known criminals or people wanted by police.
Facial recognition technology has emerged as the fastest growing technology among the biometric technologies accepted worldwide. Facial recognition techniques are estimated to grow at a CAGR of around 31 percent during 2011-2013, says a new research report “Global Biometric Forecast to 2012” from RCNOS.
If there is a match a red signal will appear on a small screen connected to the glasses, alerting the police officer of the need to take further action or make an arrest.
The devices will soon be tested at football matches and concerts and police in Brazil, South America’s biggest country, are already planning to use them during the next World Cup.
The camera will generally be used to scan faces in crowds up to 50 meters (164ft) away but can be adjusted, if searching for a specific target, to recognize faces as far as 12 miles away.