From 10,000 feet up, tracking an entire city at one glance: Ohio-based Persistent Surveillance Systems is trying to convince cities across the country that its surveillance technology can help reduce crime. Its new generation of camera technology is far more powerful than the police cameras to which America has grown accustomed. But these newer cameras have sparked some privacy concerns. A new, far more powerful generation is being quietly deployed [from small aircraft] that can track every vehicle and person across an area the size of a small city, for several hours at a time. Although these cameras can't read license plates or see faces, they provide such a wealth of data that police, businesses and even private individuals can use them to help identify people and track their movements. Already, the cameras have been flown above major public events such as the Ohio political rally where Sen. John McCain named Sarah Palin as his running mate in 2008. They've been flown above Baltimore; Philadelphia; Compton, Calif.; and Dayton [OH] in demonstrations for police. They've also been used for traffic impact studies, [and] for security at NASCAR races. Defense contractors are developing similar technology for the military, but its potential for civilian use is raising novel civil liberties concerns. In Dayton, where Persistent Surveillance Systems is based, city officials balked last year when police considered paying for 200 hours of flights, in part because of privacy complaints. The Supreme Court generally has given wide latitude to police using aerial surveillance as long as the photography captures images visible to the naked eye.