A new set of billboards that use data from mobile phones to track what people do once they pass an outdoor ad is drawing comparisonsto the film “Minority Report."

The technology, developed by Clear Channel Outdoor Americas in partnership with several carriers including AT&T, would be very useful for advertisers, says Andy Stevens, senior vice president of research and insights at the outdoor advertising arm of the communications giant now known as iHeartMedia,to the New York Times.

Privacy advocates say that technology such as the billboards could particularly catch consumers who were unaware they were being tracked.

“People have no idea that they’re being tracked and targeted,” Jeffrey Chester, executive director of the Center for Digital Democracy told the Times. “It is incredibly creepy, and it’s the most recent intrusion into our privacy.”