ActVis: Activity Visualization in Videos

We present ActVis, which is a computer-aided video surveillance system for detecting and visualizing the activation levels of multiple objects in a video. ActVis indicates "something is happening" in a video. A user arranges panels indicating the regions of focusing objects on the video screen. Temporal differential as an activation level in a panel is detected by the system, and a corresponding seek bar representing the level is generated. In general, high-level features, such as body posture or facial direction/expression, cannot be extracted when the target object is partially occluded in video, or it is not human. By employing the temporal differential as a low-level feature and the metaphor of a level meter, our system can notify a user "when something happens." The user can explore high-level features of the moment. Potential applications of ActVis include the analysis of student activation levels in classroom for professional development of faculty, and observations of wild animals for ecological investigation.