For now, Jean-Claude Latombe's robots track other robots, but they may soon be stalking us. Latombe and his fellow computer scientists at Stanford have created "autonomous observers," wheeled robots that follow other robot "targets." The four-foot-tall cylindrical observer uses cameras and lasers to make a map of its surroundings, then scouts the area for a target robot. The observer shows its human guide what it sees as it follows its prey, as well as a map of the scene with a marker for the target. It moves around obstacles and can "think ahead" to keep the target in sight. For instance, if it's tracking a target along a wall and a corner comes up, it will move outward so it can see whether or not the target turns the corner. The military is interested in using the robots to help soldiers fight urban battles, but Latombe adds that the same technology could allow a camera to track a player in a soccer game or keep the best view on a surgeon's video display. "Most people in the past have seen robots as machines that act on the world, that move objects around," says Latombe. "But something more important is to acquire information out of the world." And to accomplish that, he says, robots must be able to sense and explore their surroundings.