China is developing a system that recognizes individuals by their body shape and walking movements. Systems that recognize human faces are already being used to identify people in crowds or as a secure way to unlock personal devices. The new system, known as “gait recognition,” is already being used by police on the streets of Beijing and Shanghai. The Chinese technology company Watrix developed the system. The company announced last month that it had raised $14.5 million to speed up the development and sale of the technology. The system works in a similar way to face recognition. Cameras capture video of people in public places. Then, machines powered by artificial intelligence examine and study the video.