Isovist Analyst - An Arcview extension for planning visual surveillance

7-11 August, 2006, San Diego, CA, USA. Visual Surveillance e.g. CCTV, is now an essential part of the urban infrastructure in modern cities. One of the primary aims in visual surveillance is to ensure a maximum visual coverage of an area with the least number of visual surveillance installations, which is a NP-Hard maximal coverage problem. The planning of visual surveillance is a highly sensitive and costly task that has traditionally been done with a gut-feel process of establishing sight lines in CAD software. This paper demonstrates the ArcView extension Isovist Analyst, which automatically identifies a minimal number of potential visual surveillance sites that ensure complete visual coverage of an area. The paper proposes a Stochastical Rank and Overlap Elimination (S-ROPE) method, which iteratively identifies the optimal visual surveillance sites. S-ROPE method is essentially based on a greedy search technique, which has been improved by a combination of selective sampling strategy and random initialisation

Establishing the behavioural limits for countershaded camouflage

Countershading is a ubiquitous patterning of animals whereby the side that typically faces the highest illumination is darker. When tuned to specific lighting conditions and body orientation with respect to the light field, countershading minimizes the gradient of light the body reflects by counterbalancing shadowing due to illumination, and has therefore classically been thought of as an adaptation for visual camouflage. However, whether and how crypsis degrades when body orientation with respect to the light field is non-optimal has never been studied. We tested the behavioural limits on body orientation for countershading to deliver effective visual camouflage. We asked human participants to detect a countershaded target in a simulated three-dimensional environment. The target was optimally coloured for crypsis in a reference orientation and was displayed at different orientations. Search performance dramatically improved for deviations beyond 15 degrees. Detection time was significantly shorter and accuracy significantly higher than when the target orientation matched the countershading pattern. This work demonstrates the importance of maintaining body orientation appropriate for the displayed camouflage pattern, suggesting a possible selective pressure for animals to orient themselves appropriately to enhance crypsis

Wideband performance comparison between the 40 GHz and 60 GHz frequency bands for indoor radio channels

When 5G networks are to be deployed, the usability of millimeter-wave frequency allocations seems to be left out of the debate. However, there is an open question regarding the advantages and disadvantages of the main candidates for this allocation: The use of the licensed spectrum near 40 GHz or the unlicensed band at 60 GHz. Both bands may be adequate for high performance radio communication systems, and this paper provides insight into such alternatives. A large measurement campaign supplied enough data to analyze and to evaluate the network performance for both frequency bands in different types of indoor environments: Both large rooms and narrow corridors, and both line of sight and obstructed line of sight conditions. As a result of such a campaign and after a deep analysis in terms of wideband parameters, the radio channel usability is analyzed with numerical data regarding its performance

Wideband performance comparison between the 40 GHz and 60 GHz frequency bands for indoor radio channels

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Indoor wireless communications and applications

Chapter 3 addresses challenges in radio link and system design in indoor scenarios. Given the fact that most human activities take place in indoor environments, the need for supporting ubiquitous indoor data connectivity and location/tracking service becomes even more important than in the previous decades. Specific technical challenges addressed in this section are(i), modelling complex indoor radio channels for effective antenna deployment, (ii), potential of millimeter-wave (mm-wave) radios for supporting higher data rates, and (iii), feasible indoor localisation and tracking techniques, which are summarised in three dedicated sections of this chapter

Axial plane optical microscopy.

We present axial plane optical microscopy (APOM) that can, in contrast to conventional microscopy, directly image a sample's cross-section parallel to the optical axis of an objective lens without scanning. APOM combined with conventional microscopy simultaneously provides two orthogonal images of a 3D sample. More importantly, APOM uses only a single lens near the sample to achieve selective-plane illumination microscopy, as we demonstrated by three-dimensional (3D) imaging of fluorescent pollens and brain slices. This technique allows fast, high-contrast, and convenient 3D imaging of structures that are hundreds of microns beneath the surfaces of large biological tissues

Interactive global illumination on the CPU

Computing realistic physically-based global illumination in real-time remains one of the major goals in the fields of rendering and visualisation; one that has not yet been achieved due to its inherent computational complexity. This thesis focuses on CPU-based interactive global illumination approaches with an aim to develop generalisable hardware-agnostic algorithms. Interactive ray tracing is reliant on spatial and cache coherency to achieve interactive rates which conflicts with needs of global illumination solutions which require a large number of incoherent secondary rays to be computed. Methods that reduce the total number of rays that need to be processed, such as Selective rendering, were investigated to determine how best they can be utilised. The impact that selective rendering has on interactive ray tracing was analysed and quantified and two novel global illumination algorithms were developed, with the structured methodology used presented as a framework. Adaptive Inter- leaved Sampling, is a generalisable approach that combines interleaved sampling with an adaptive approach, which uses efficient component-specific adaptive guidance methods to drive the computation. Results of up to 11 frames per second were demonstrated for multiple components including participating media. Temporal Instant Caching, is a caching scheme for accelerating the computation of diffuse interreflections to interactive rates. This approach achieved frame rates exceeding 9 frames per second for the majority of scenes. Validation of the results for both approaches showed little perceptual difference when comparing against a gold-standard path-traced image. Further research into caching led to the development of a new wait-free data access control mechanism for sharing the irradiance cache among multiple rendering threads on a shared memory parallel system. By not serialising accesses to the shared data structure the irradiance values were shared among all the threads without any overhead or contention, when reading and writing simultaneously. This new approach achieved efficiencies between 77% and 92% for 8 threads when calculating static images and animations. This work demonstrates that, due to the flexibility of the CPU, CPU-based algorithms remain a valid and competitive choice for achieving global illumination interactively, and an alternative to the generally brute-force GPU-centric algorithms

Wireless Channel Models for Indoor Environments

Wireless networks have made significant advancement in recent times by adding a new dimension to theway people communicate. Development of wireless standards have constantly aimed at providing higher datarates even under complex environments using smart antennas, multiple-input, and multiple-output systems.This has necessitated an understanding of the indoor propagation channel. Channel models describe acommunication channel and are essential in developing efficient wireless communication networks. This papersurveys different channel models used to characterise wireless indoor environment. This survey may be usefulfor the army, where the communication over wide areas during wargames that they hold periodically, isnecessary. Moreover, it may also be useful for communication near the border areas for surveillance operations.Defence Science Journal, 2008, 58(6), pp.771-777, DOI:http://dx.doi.org/10.14429/dsj.58.170

Wideband mobile propagation channels: Modelling measurements and characterisation for microcellular environments

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Real-time selective rendering

Traditional physically-based renderers can produce highly realistic imagery; however, suffer from lengthy execution times, which make them impractical for use in interactive applications. Selective rendering exploits limitations in the human visual system to render images that are perceptually similar to high-fidelity renderings in a fraction of the time. This paper outlines current research being carried out by the author to tackle this problem, using a combination of ray-tracing acceleration techniques, GPU-based processing, and selective rendering methods. The research will also seek to confirm results published in literature, which indicate that users fail to notice any quality degradation between high-fidelity imagery and a corresponding selective rendering.peer-reviewe