ACVT has been working in the field of surveillance for many years. Much of this work has been in the Defence and Security space with DSTO and other Defence agencies. This has included involvement in Coastwatch and working on applications such as airborne surveillance imagery from UAVs. A focus of more recent work, some of which has been patented, has been automation in monitoring video from many cameras to generate an understanding of the paths which targets may take between their fields of view. ACVT employs novel methods for estimating the activity topology of a set of cameras based on an exclusion approach. The method is computationally fast, and does not rely on the tracking of objects within each camera view. In contrast to most existing methods for activity topology determination, it does not attempt to build up evidence for camera proximity over time. Instead, it uses observed activity to rule out topologies over time. Such approaches bring significant technical and economic benefits, particularly as the proliferation of surveillance cameras throughout public places has far outpaced the development of software to monitor the video they generate. The exclusion approach to topology estimation has been licenced to SNAP Network Surveillance for commercialisation, but the work in this area continues within the ACVT. Current projects are looking at improving the tracking of targets between cameras, and improving the topology estimation process.