Christopher S. Madden

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Tracking single individuals as they move across disjoint camera views is a challenging task since their appearance may vary significantly between views. Major changes in appearance are due to different and varying illumination conditions and the deformable geometry of people. These effects are hard to estimate and take into account in real-life(More)
This paper presents a framework based on robust shape and appearance features for matching the various tracks generated by a single individual moving within a surveillance system. Each track is first automatically analysed in order to detect and remove the frames affected by large segmentation errors and drastic changes in illumination. The object’s(More)
The increased flexibility and other benefits offered by IP network cameras makes them a common choice for installation in new and expanded surveillance networks. One commonly quoted limitation of IP cameras is their high latency when compared to their analogue counterparts. This causes some reluctance to install or upgrade to digital cameras, and is slowing(More)
This paper investigates a method of visualising internet traffic data using the underlying spherical nature of the globe. The method uses data about the traffic between Autonomous Systems (ASes) that are the communications on the public internet system. This data is displayed as a set of nodes with connecting edges overlaying the threedimensional spherical(More)
This paper investigates the use of pairwise camera overlap estimates for supporting target tracking across large networks of surveillance cameras. We compare the use of camera overlap topology information to a method based on matching target appearance histograms, and also evaluate the effect of combining both methods. Tracking accuracy results are reported(More)
Automatic placement of surveillance cameras in arbitrary buildings is a challenging task, and also one that is essential for efficient deployment of large scale surveillance networks. Existing approaches for automatic camera placement are either limited to a small number of cameras, or constrained in terms of the building layouts to which they can be(More)
Several techniques have been proposed to date to build colour invariants between camera views with varying illumination conditions. In this paper, we propose to improve colour invariance by using data-dependent techniques. To this aim, we compare the effectiveness of histogram stretching, illumination filtration, full histogram equalisation and controlled(More)
Tracking people by their appearance across disjoint camera views is challenging since appearance may vary significantly across such views. This problem has been tackled in the past by computing intensity transfer functions between each camera pair during an initial training stage. However, in real-life situations, intensity transfer functions depend not(More)
This paper presents a novel framework designed for calculating the topology of overlapping cameras in large surveillance systems. Such a framework is a key enabler for efficient network-wide surveillance, e.g. inter-camera tracking, especially in large surveillance networks. The framework presented can be adapted to utilise numerous contradiction and(More)
This paper presents a method to identify frames with significant segmentation errors in an individual's track by analysing the changes in appearance and size features along the frame sequence. The features used and compared include global colour histograms, local histograms and the bounding box' size. Experiments were carried out on 26 tracks from 4(More)