Visual surveillance using deformable models of vehicles

This paper presents recent developments to a vision-based traffic surveillance system which relies extensively on the use of geometrical and scene context. Firstly, a highly parametrised 3-D model is reported, able to adopt the shape of a wide variety of different classes of vehicle (e.g. cars, vans, buses etc.), and its subsequent specialisation to a generic car class which accounts for commonly encountered types of car (including saloon, batchback and estate cars). Sample data collected from video images, by means of an interactive tool, have been subjected to principal component analysis (PCA) to define a deformable model having 6 degrees of freedom. Secondly, a new pose refinement technique using “active” models is described, able to recover both the pose of a rigid object, and the structure of a deformable model; an assessment of its performance is examined in comparison with previously reported “passive” model-based techniques in the context of traffic surveillance. The new method is more stable, and requires fewer iterations, especially when the number of free parameters increases, but shows somewhat poorer convergence. Typical applications for this work include robot surveillance and navigation tasks.

Performance statistics of a head-operated force-reflecting rehabilitation robot system

Researchers in the rehabilitation engineering community have been designing and developing a variety of passive/active devices to help persons with limited upper extremity function to perform essential daily manipulations. Devices range from low-end tools such as head/mouth sticks to sophisticated robots using vision and speech input. While almost all of the high-end equipment developed to date relies on visual feedback alone to guide the user providing no tactile or proprioceptive cues, the “low-tech” head/mouth sticks deliver better “feel” because of the inherent force feedback through physical contact with the user's body. However, the disadvantage of a conventional head/mouth stick is that it can only function in a limited workspace and the performance is limited by the user's strength. It therefore seems reasonable to attempt to develop a system that exploits the advantages of the two approaches: the power and flexibility of robotic systems with the sensory feedback of a headstick. The system presented in this paper reflects the design philosophy stated above. This system contains a pair of master-slave robots with the master being operated by the user's head and the slave acting as a telestick. Described in this paper are the design, control strategies, implementation and performance evaluation of the head-controlled force-reflecting telestick system.

Operator performance evaluation of controlled depth of field in a stereographically displayed virtual environment

Retinal blurring resulting from the human eye's depth of focus has been shown to assist visual perception. Infinite focal depth within stereoscopically displayed virtual environments may cause undesirable effects, for instance, objects positioned at a distance in front of or behind the observer's fixation point will be perceived in sharp focus with large disparities thereby causing diplopia. Although published research on incorporation of synthetically generated Depth of Field (DoF) suggests that this might act as an enhancement to perceived image quality, no quantitative testimonies of perceptional performance gains exist. This may be due to the difficulty of dynamic generation of synthetic DoF where focal distance is actively linked to fixation distance. In this paper, such a system is described. A desktop stereographic display is used to project a virtual scene in which synthetically generated DoF is actively controlled from vergence-derived distance. A performance evaluation experiment on this system which involved subjects carrying out observations in a spatially complex virtual environment was undertaken. The virtual environment consisted of components interconnected by pipes on a distractive background. The subject was tasked with making an observation based on the connectivity of the components. The effects of focal depth variation in static and actively controlled focal distance conditions were investigated. The results and analysis are presented which show that performance gains may be achieved by addition of synthetic DoF. The merits of the application of synthetic DoF are discussed.

A helmet mounted display system with active gaze control for visual telepresence

The objective of a Visual Telepresence System is to provide the operator with a high fidelity image from a remote stereo camera pair linked to a pan/tilt device such that the operator may reorient the camera position by use of head movement. Systems such as these which utilise virtual reality style helmet mounted displays have a number of limitations. The geometry of the camera positions and of the displays is generally fixed and is most suitable only for viewing elements of a scene at a particular distance. To address such limitations, a prototype system has been developed where the geometry of the displays and cameras is dynamically controlled by the eye movement of the operator. This paper explores why it is necessary to actively adjust the display system as well as the cameras and justifies the use of mechanical adjustment of the displays as an alternative to adjustment by electronic or image processing methods. The electronic and mechanical design is described including optical arrangements and control algorithms. The performance and accuracy of the system is assessed with respect to eye movement.

Mirror lightpipes: daylighting performance in real buildings

Mirror lightpipes are useful for providing healthy and energy-efficient daylight into buildings where windows and skylights are unsuitable, insufficient or generate too much heat gain. The lightpipes have been installed in dozens of buildings in the UK. Field monitoring has been carried out to assess their performance in four different buildings: the headquaters of a major insurance company, a health clinic, a residential building and a college dining hall In those cases where lighipipes with moderate aspect ratios were installed, good illuminance of up to 450 lux has been obtained with internal/external illuminance ratios around 1%. When long and narrow lightpipes with many bends are used, however, the ratio reduced to around 0.1%. These results showed that lightpipes can be effective daylighting devices provided that excessive aspect ratios and numbers of bends are avoided. Lightpipes with larger diameters should be used whenever possible. The lightpipes often improved signiScantly the visual quality af the interior environment, and high user satisfaction was found even in buildings where a relatively low level of daylight was admitted through the lightpipes

Visual enhancement of touch in spatial body representation

Perception of our own bodies is based on integration of visual and tactile inputs, notably by neurons in the brain’s parietal lobes. Here we report a behavioural consequence of this integration process. Simply viewing the arm can speed up reactions to an invisible tactile stimulus on the arm. We observed this visual enhancement effect only when a tactile task required spatial computation within a topographic map of the body surface and the judgements made were close to the limits of performance. This effect of viewing the body surface was absent or reversed in tasks that either did not require a spatial computation or in which judgements were well above performance limits. We consider possible mechanisms by which vision may influence tactile processing.

A demonstration of 'broken' visual space

It has long been assumed that there is a distorted mapping between real and ‘perceived’ space, based on demonstrations of systematic errors in judgements of slant, curvature, direction and separation. Here, we have applied a direct test to the notion of a coherent visual space. In an immersive virtual environment, participants judged the relative distance of two squares displayed in separate intervals. On some trials, the virtual scene expanded by a factor of four between intervals although, in line with recent results, participants did not report any noticeable change in the scene. We found that there was no consistent depth ordering of objects that can explain the distance matches participants made in this environment (e.g. A > B > D yet also A < C < D) and hence no single one-to-one mapping between participants’ perceived space and any real 3D environment. Instead, factors that affect pairwise comparisons of distances dictate participants’ performance. These data contradict, more directly than previous experiments, the idea that the visual system builds and uses a coherent 3D internal representation of a scene.

Performance as social practice

Starting point for these outputs is a large scale research project in collaboration with the Zurich University for the Arts and the Kunstmuseum Thun, looking at a redefinition of Social Sculpture (Joseph Beuys/ Bazon Brock, 1970) as a functional device re-deployed to expand the art discourse into a societal discourse. Although Beuys‘ version of a social sculpture involved notions of abstruse mysticism and reformulations of a national identity these were never-the less part of a social transformation that shifted and re-arranged power relations. Following Laclau and Mouffe in their contention that democray is a fundamentally antagonistic process and contesting Grant Kester’s understanding of a ethically based relational practice, this work is alignes itself with Hirschhorn’s claim to an aesthetic practice within communities, following the possibility to view a socially based practice from both ends of the ethics debate, whereby ethical aspects fuels the aethetic to “create situations that are beautiful because they are ethical and shocking because they are ethical, thus in turn aesthetic because they are ethical” (O’Donnell). This project sets out to engage in activities which interact with surrounding communities and evoce new imaginations of site, thereby understanding site as a catalysts for subjective emergences. Performance is tested as a site for social practice. Archival research into local audio/visual resources, such as the Swiss Radio Archive, the Swiss Military Film Archives and zoological film archives of the Basel Zoo, was instrumental to the navigation of this work, under theme of crisis, catastrophy, landscape, fallout, in order to create a visual language for an active performance site. Commissioned by the Kunstmuseum Thun in collaboration with the University for the Arts in Zurich as part of a year long exhibition programme, (other artists are Jeanne Van Heeswijk (NL) and San Keller (CH), ) this project brings together a series of different works in a new performace installation. The performance process includes a performance workshop with 30 school children from local Swiss schools and their teachers, which was conducted publicly in the museum spaces. It enabled the children to engage with an unexpected set of tribal and animalistic behaviours, looking at situations of flight and rescue, resulting in a large performance choreography orchestration without an apparent conductor, it includes a collaboration with renowned Swiss zoologist, Prof Klaus Zuberbühler(University of St Andrews) and the Colonal General Haldimann commander of the military base in Thun. The installation included 2 static video images, shot in an around spectacular local cave site (Beatus Caves) including 3 children. The project will culminate in an edited edition of the Oncurating Journal, (issue no, tbc, in 2012) including interviews and essays from project collaborators. (Army Commander General, Thun, Jörg Hess, performance script, Timothy Long, and others)

Robust abandoned object detection integrating wide area visual surveillance and social context

This paper presents a video surveillance framework that robustly and efficiently detects abandoned objects in surveillance scenes. The framework is based on a novel threat assessment algorithm which combines the concept of ownership with automatic understanding of social relations in order to infer abandonment of objects. Implementation is achieved through development of a logic-based inference engine based on Prolog. Threat detection performance is conducted by testing against a range of datasets describing realistic situations and demonstrates a reduction in the number of false alarms generated. The proposed system represents the approach employed in the EU SUBITO project (Surveillance of Unattended Baggage and the Identification and Tracking of the Owner).

Direct evidence for attention-dependent influences of the frontal eye-fields on feature-responsive visual cortex

Voluntary selective attention can prioritize different features in a visual scene. The frontal eye-fields (FEF) are one potential source of such feature-specific top-down signals, but causal evidence for influences on visual cortex (as was shown for "spatial" attention) has remained elusive. Here, we show that transcranial magnetic stimulation (TMS) applied to right FEF increased the blood oxygen level-dependent (BOLD) signals in visual areas processing "target feature" but not in "distracter feature"-processing regions. TMS-induced BOLD signals increase in motion-responsive visual cortex (MT+) when motion was attended in a display with moving dots superimposed on face stimuli, but in face-responsive fusiform area (FFA) when faces were attended to. These TMS effects on BOLD signal in both regions were negatively related to performance (on the motion task), supporting the behavioral relevance of this pathway. Our findings provide new causal evidence for the human FEF in the control of nonspatial "feature"-based attention, mediated by dynamic influences on feature-specific visual cortex that vary with the currently attended property.

Backtracks: a devised performance

Backtracks aimed to investigate critical relationships between audio-visual technologies and live performance, emphasising technologies producing sound, contrasted with non-amplified bodily sound. Drawing on methodologies for studying avant garde theatre, live performance and the performing body, it was informed by work in critical and cultural theory by, for example, Steven Connor and Jonathan Rée, on the body's experience and interpretation of sound. The performance explored how shifting national boundaries, mobile workforces, complex family relationships, cultural pluralities and possibilities for bodily transformation have compelled a re-evaluation of what it means to feel 'at home' in modernity. Using montages of live and mediated images, disrupted narratives and sound, it evoked destablised identities which characterise contemporary lived experience, and enacted the displacement of certainties provided by family and nation, community and locality, body and selfhood. Homer's Odyssey framed the performance: elements could be traced in the mise-en-scène; in the physical presence of Athene, the narrator and Penelope weaving mementoes from the past into her loom; and in voice-overs from Homer's work. The performance drew on personal experiences and improvisations, structured around notions of journey. It presented incomplete narratives, memories, repressed anxieties and dreams through different combinations of sounds, music, mediated images, movement, voice and bodily sound. The theme of travel was intensified by performers carrying suitcases and umbrellas, by soundtracks incorporating travel effects, and by the distorted video images of forms of transport playing across 'screens' which proliferated across the space (sails, umbrellas, the loom, actors' bodies). The performance experimented with giving sound and silence performative dimensions, including presenting sound in visual and imagistic ways, for example by using signs from deaf sign language. Through-composed soundtracks of live and recorded song, music, voice-over, and noise exploited the viscerality of sound and disrupted cognitive interpretation by phenomenological, somatic experience, thereby displacing the impulse for closure/destination/home.

Using Delboeuf's illusion to improve point and click performance for older adults

Older computer users often exhibit poorer performance in point and click tasks on a computer than younger adults. This paper reports on the first phase of research that examines whether a visual illusion that makes an object appear to be larger (Delboeuf‟s Illusion), can help to improve point and click performance for older computer users. In this first phase, we look at the effect sizes for different configurations of the Delboeuf illusion. The study finds that the target size is overestimated by 8% for both older and younger adults in one configuration, and 12% for older adults in another configuration. The results will inform the design of a second phase, in which the configurations which demonstrate the largest effects will be investigated using a Fitts‟-style study of pointing performance.

Postmodernism, culture and feminism: the aesthetics of space and performance in Rock Follies and Rock Follies of '77

This article discusses the aesthetic and spatial representational strategies of the popular studio-based musical television drama serials Rock Follies and Rock Follies of ’77. It analyses how the texts’ themes relating to women and the entertainment industry are mediated through their postmodern ironic mode and representation of fantastic spaces. Rock Follies’ distinctive stylised aesthetic and mode of caricature are analysed with reference to the visual intentions and ‘voice’ of the writer, Howard Schuman. Through considering the programmes’ various spatial strategies, the article draws attention to the importance of visual and performance style in their postmodern discourse on culture, fantasy, gender and subjectivity. Analysis of the spaces of musical performance, characters’ domestic environments and simulated entertainment spaces reveals how a dialectic is established between the escapist imaginative pleasures of fantasy and the manipulative and exploitative practices of the culture industry. The shift from the optimism of the first series, when the LittleLadies first form, to the darker mood of the second series, in which they are increasingly divided by industry pressures, is traced through changes in the aesthetics of space and characterisation. As a space of artifice, performance and electronic visual manipulation that facilitates the texts’ reflexive representation of culture and feminised fantasy, the studio’s unique aesthetic strengths emerge through this case study.

“There’s something very familiar about all this”: generic play and performance in the Back to the Future trilogy (Robert Zemeckis, 1985, 1989, 1990)

The Back to the Future Trilogy incorporates several different generic elements, including aspects of the fifties teen movie, science fiction, comedy and the western. These different modes playfully intertwine with each other creating a complex world of repetitions, echoes and modulations. This essay seeks to interrogate the construction of generic elements and the play between them through a close analysis of a repeated performance. Genre is signalled through various strategies employed within the construction of mise-en-scène, a significant portion of this, as I would like to argue, is transmitted through performance. The material detail of a performance – incorporating gesture, movement, voice, and even surrounding elements such as costume – as well as the way it its presented within a film is key to the establishment, invocation and coherence of genre. Furthermore, attention to the complexity of performance details, particularly in the manner in which they reverberate across texts, demonstrates the intricacy of genre and its inherent mutability. The Back to the Future trilogy represents a specific interest in the flexibility of genre. Within each film, and especially across all three, aspects of various genres are interlaced through both visual and narrative detail, thus constructing a dense layer of references both within and without the texts. To explore this patterning in more detail I will interrogate the contribution of performance to generic play through close analysis of Thomas F. Wilson’s performance of Biff/Griff/Burford Tannen and his central encounter with Marty McFly (Michael J. Fox) in each film. These moments take place in a fifties diner, a 1980s retro diner and a saloon respectively, each space contributing the similarities and differences in each repetition. Close attention to Wilson’s performance of each related character, which contains both modulations and repetitions used specifically to place each film’s central generic theme, demonstrates how embedded the play between genres and their flexibility is within the trilogy.

Distraction control processes in free recall: benefits and costs to performance

How is semantic memory influenced by individual differences under conditions of distraction? This question was addressed by observing how visual target words—drawn from a single category—were recalled whilst ignoring spoken distracter words that were either members of the same, or members of a different (single) category. Working memory capacity (WMC) was related to disruption only with synchronous, not asynchronous, presentation and distraction was greater when the words were presented synchronously. Subsequent experiments found greater negative priming of distracters amongst individuals with higher WMC but this may be dependent on targets and distracters being comparable category exemplars. With less dominant category members as distracters, target recall was impaired – relative to control – only amongst individuals with low WMC. The results highlight the role of cognitive control resources in target-distracter selection and the individual-specific cost implications of such cognitive control.