A Web-based, Real-time Video Surveillance System by Leveraging PTZ Cameras

Abstract

Video surveillance systems are commonly used for environmental monitoring. Nevertheless, existing systems such as [1, 2] can only monitor scenes statically. When an accident or a fire event happens, we cannot get the critical pictures and check those situations immediately. Therefore, we propose to leverage pan-tilt-zoom (PTZ) cameras and develop a real-time surveillance system, where the PTZ cameras can rotate in a horizontal plane by panning and in a vertical plane by tilting, and adjust the focal length by zooming, so we can control these cameras dynamically for the emergent area. Especially for the accessibility, we implement this system as a web service to help users easily define the emergent area and preview the video of cameras remotely. Specifically, our system is composed of multiple PTZ cameras and a web server, as shown in Fig. 1. The PTZ cameras are with fixed positions and can be controlled to pan, tilt, and zoom remotely by the web server. The web server maintains a website to provide the real-time surveillance service, consisting of two procedures: area setting and video displaying. The area setting is for users to define the monitored area, including the range and location of the monitored area. Then, all the cameras will be dispatched and face to the center of the monitored area. Finally, the video displaying procedure will show the monitoring results, including the video streams and the rotation parameters of the dispatched cameras. Fig. 2 shows the control panel of the implemented prototype, where there are two PTZ cameras deployed in the monitoring environment. On this panel, the left part is for video displaying and the right part is for the monitored area setting. More specifically, for the right part, the upper side is the floor plan of the monitoring environment which users can define the location of the emergent area by clicking on. On the lower left side, users can further specify the details of the area, such as its length and width. After setting, the monitored area will be marked as the red-dotted rectangle on the floor plan. Finally, the monitoring results, such as the coverage ratio of the monitored area and the rotation parameters of the cameras, will be shown on the lower central side. Note that the system also allows users to control the cameras manually on the lower right side.