We can obtain massive data from both physical and cyber space of our society. For example, the CCTV cameras can capture the real-time video data related to surveillance scenes, objects, human, cars, etc. And the social media such as website, blog, micro-blog, BBS provides the thoughts and feelings of people. The social sensing data in both physical space and cyber space is closely related to the public security. So the project aims to extract useful security-related information from the social sensing data. The main research topics include cross-camera events understanding, cross-media data mining of social media, and cross-space social sensing data processing.