ZHENGZHOU, China — They perch on poles and glare from streetlamps. Some hang barely visible in the ceiling of the subway, and others seem to stretch out on braced necks and peer into your eyes.

Surveillance cameras are everywhere in China.

I pass more than 200 on my 30-minute commute in Shanghai. After a while, they mostly blend into the background. But when spotting a new one, I wonder about them. Is anyone watching? Is a computer parsing the feed? Is it even on?

Trying to get to the bottom of these questions can be infuriating. Chinese people are often unwilling to talk about their run-ins with the police. And the authorities are usually under standing orders not to talk to foreign journalists about much of anything, let alone cutting-edge technologies that snoop on criminals.

[Read more on China’s efforts to assemble a vast national surveillance system.]

So when I got the chance to see the world through the eyes of a police camera, it was oddly exhilarating. As it goes with reporting in China, often you just have to show up, camp out and hope for the best. In my case, patience and a hefty dose of luck paid off.