Detection of thrown objects in indoor and outdoor scenes

We present a novel technique for the detection of thrown objects and other free-flying bodies in video sequences. Our method runs in real-time and was designed to be used as a component in a deployed surveillance system. We detect regions of interesting motion that fit certain size, compactness and speed criteria, and use the expectation maximization algorithm to detect objects on parabolic trajectories over a short time window. The system was shown to successfully detect thrown objects of various sizes in a large test set of indoor and outdoor videos.