Steve Maddock

Steve Maddock
The University of Sheffield | Sheffield · Department of Computer Science (Faculty of Engineering)

BSc, PGCE, PhD

About

125
Publications
51,536
Reads
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918
Citations

Publications

Publications (125)
Conference Paper
Neural Style Transfer (NST) is concerned with the artistic stylization of visual media. It can be described as the process of transferring the style of an artistic image onto an ordinary photograph. Recently, a number of studies have considered the enhancement of the depth-preserving capabilities of the NST algorithms to address the undesired effec...
Article
Full-text available
Ultraviolet colouration is thought to be an important form of signalling in many bird species, yet broad insights regarding the prevalence of ultraviolet plumage colouration and the factors promoting its evolution are currently lacking. In this paper, we develop a image segmentation pipeline based on deep learning that considerably outperforms clas...
Article
Full-text available
Railway networks systems are by design open and accessible to people, but this presents challenges in the prevention of events such as terrorism, trespass, and suicide fatalities. With the rapid advancement of machine learning, numerous computer vision methods have been developed in closed-circuit television (CCTV) surveillance systems for the purp...
Preprint
Neural Style Transfer (NST) is concerned with the artistic stylization of visual media. It can be described as the process of transferring the style of an artistic image onto an ordinary photograph. Recently, a number of studies have considered the enhancement of the depth-preserving capabilities of the NST algorithms to address the undesired effec...
Conference Paper
Investigating automatic methods for the early detection of dementia and related conditions that cause cognitive impairment is an area of growing interest. Video processing could play a role by providing a non-invasive and low-cost alternative to current expensive assessments. For this to be successful it is crucial that approaches are robust to in-...
Preprint
Full-text available
Revealing the functioning of non-standard visual systems such as compound eyes is of interest to biologists and engineers alike. A key investigative method is to replicate the sensory apparatus using artificial systems, allowing for investigation of the visual information that drives animal behaviour when exposed to environmental cues. To date, 'Co...
Article
Ultraviolet (UV) colouration is thought to be an important signalling mechanism in many bird species, yet broad insights regarding the prevalence of UV plumage colouration and the factors promoting its evolution are currently lacking. Here, we develop a novel image segmentation pipeline based on deep learning that considerably outperforms classical...
Preprint
Full-text available
Ultraviolet (UV) colouration is thought to be an important signalling mechanism in many bird species, yet broad insights regarding the prevalence of UV plumage colouration and the factors promoting its evolution are currently lacking. Here, we develop a novel image segmentation pipeline based on deep learning that considerably outperforms classical...
Conference Paper
Closer interaction in Human-Robot Collaboration (HRC) could result in increased worker efficiency in manufacturing situations. However, physical cages often limit this. Our research is investigating the potential for using Augmented Reality (AR) to visualise virtual safety zones, thus replacing real cages. This paper presents initial experiments to...
Article
Controlling crowd simulations typically involves tweaking complex parameter sets to attempt to reach a desired outcome, which can be unintuitive for nontechnical users. This paper presents an approach to control pedestrian simulations in real time via sketching. Users are able to create entrances/exits, barriers to block paths, flow lines to guide...
Conference Paper
AR art is a relatively recent phenomenon, one that brings innovation in the way that artworks can be produced and presented in real-world locations and environments. We present an AR art app, running in real time on a smartphone, that can be used to bring to life inanimate objects such as statues. The work relies on a virtual copy of the real objec...
Article
Full-text available
Craniofacial reconstruction (CFR) has been widely used to produce the facial appearance of an unidentified skull in the realm of forensic science. Many studies have indicated that the computerized CFR approach is fast, flexible, consistent and objective in comparison to the traditional manual CFR approach. This paper presents a computerized CFR sys...
Preprint
Full-text available
Understanding how people view and interact with autonomous vehicles is important to guide future directions of research. One such way of aiding understanding is through simulations of virtual environments involving people and autonomous vehicles. We present a simulation model that incorporates people and autonomous vehicles in a shared urban space....
Chapter
Understanding how people view and interact with autonomous vehicles is important to guide future directions of research. One such way of aiding understanding is through simulations of virtual environments involving people and autonomous vehicles. We present a simulation model that incorporates people and autonomous vehicles in a shared urban space....
Conference Paper
Flying insects display a repertoire of complex behaviours that are facilitated by their non-standard visual system that if understood would offer solutions for weight- and power- constrained robotic platforms such as micro unmanned aerial vehicles (MUAVs). Crucial to this goal is revealing the specific features of insect eyes that engineered soluti...
Article
Full-text available
Complex systems simulations are well suited to the SIMT paradigm of GPUs, enabling millions of actors to be processed in fractions of a second. At the core of many such simulations, fixed radius near neighbours (FRRN) search provides the actors with spatial awareness of their neighbours. The FRNN search process is frequently the limiting factor of...
Preprint
Full-text available
Real-time large-scale crowd simulations with realistic behavior, are important for many application areas. On CPUs, the ORCA pedestrian steering model is often used for agent-based pedestrian simulations. This paper introduces a technique for running the ORCA pedestrian steering model on the GPU. Performance improvements of up to 30 times greater t...
Article
Full-text available
The performance and scalability of macroscopic assignment and simulation software limits the quantity, scale and complexity of simulations of transport networks that are used to aid the planning, design and operation of transport systems. Through the application of many-core processing architectures (such as Graphics Processing Units (GPUs)) and da...
Chapter
Real-time large-scale crowd simulations with realistic behavior, are important for many application areas. On CPUs, the ORCA pedestrian steering model is often used for agent-based pedestrian simulations. This paper introduces a technique for running the ORCA pedestrian steering model on the GPU. Performance improvements of up to 30 times greater t...
Conference Paper
Real-time large-scale crowd simulations with realistic behavior, are important for many application areas. On CPUs, the ORCA pedestrian steering model is often used for agent-based pedestrian simulations. This paper introduces a technique for running the ORCA pedestrian steering model on the GPU. Performance improvements of up to 30 times greater t...
Article
Full-text available
Physically-based mouth models operate on the principle that a better mouth animation will be produced by simulating physically accurate behaviour of the mouth. In the development of these models, it is useful to have an evaluation approach which can be used to judge the effectiveness of a model and draw comparisons against other models and real-lif...
Conference Paper
Full-text available
In visual speech animation, lip motion accuracy is of paramount importance for speech intelligibility, especially for the hard of hearing or foreign language learners. We present an approach for visual speech animation that uses tracked lip motion in front-view 2D videos of a real speaker to drive the lip motion of a synthetic 3D head. This makes u...
Article
This paper presents a novel, high-performance, graphical processing unit-based algorithm for efficiently solving two-dimensional linear programs in batches. The domain of two-dimensional linear programs is particularly useful due to the prevalence of relevant geometric problems. Batch linear programming refers to solving numerous different linear p...
Conference Paper
Controlling crowd simulations typically involves tweaking complex parameter sets to attempt to reach a desired outcome, which can be unintuitive for non-technical users. This paper presents an approach to control pedestrian simulations in real time via sketching. Most previous work has relied on grid-based navigation to support the sketching approa...
Article
Introduction Virtual reality (VR) is gaining recognition as a valuable tool for training dental students and its use by dental schools around the world is growing. It is timely to review the literature relating to the use of VR in dental education, in order to ensure that educators are well-informed of current areas of inquiry, and those requiring...
Article
This paper presents a bi-view (front and side) audiovisual Lombard speech corpus, which is freely available for download. It contains 5400 utterances (2700 Lombard and 2700 plain reference utterances), produced by 54 talkers, with each utterance in the dataset following the same sentence format as the audiovisual “Grid” corpus [Cooke, Barker, Cunni...
Article
Full-text available
When producing speech in noisy backgrounds talkers reflexively adapt their speaking style in ways that increase speech-in-noise intelligibility. This adaptation, known as the Lombard effect, is likely to have an adverse effect on the performance of automatic speech recognition systems that have not been designed to anticipate it. However, previous...
Technical Report
Full-text available
This study describes the learning potential of serious games and their success in a number of domains such as the military, healthcare, education, and emergency services. The work aims to highlight the training opportunities available for serious games in the police domain in general, and in the Dubai police force in particular, and the challenges...
Article
Full-text available
Road network microsimulation is computationally expensive, and existing state of the art commercial tools use task parallelism and coarse-grained data-parallelism for multi-core processors to achieve improved levels of performance. An alternative is to use Graphics Processing Units (GPUs) and fine-grained data parallelism. This paper describes a GP...
Article
Previous studies have used principal component analysis (PCA) to investigate the craniofacial relationship, as well as sex determination using facial factors. However, few studies have investigated the extent to which the choice of principal components (PCs) affects the analysis of craniofacial relationship and sexual dimorphism. In this paper, we...
Article
Visual speech information plays a key role in supporting speech perception, especially when acoustic features are distorted or inaccessible. Recent research suggests that for spectrally distorted speech, the use of visual speech in auditory training improves not only subjects’ audiovisual speech recognition, but also their subsequent auditory-only...
Conference Paper
Crowd simulations are used in various fields such as entertainment, training systems and city planning. However, controlling the behaviour of the pedestrians typically involves tuning of the system parameters through trial and error, a time-consuming process relying on knowledge of a potentially complex parameter set. This paper presents an interac...
Conference Paper
Many agent based models require agents to have an awareness of their local peers. The handling of these fixed radius near neighbours (FRNNs) is often a limiting factor of performance. However without a standardised metric to assess the handling of FRNNs, contributions to the field lack the rigorous appraisal necessary to expose their relative benef...
Conference Paper
The use of a terrestrial laser scanner (TLS) has become a popular technique for the acquisition of 3D scenes in architecture and design. Surface reconstruction is used to generate a digital model from the acquired point clouds. However, the model often consists of excessive data, limiting real-time user experiences that make use of the model. In th...
Conference Paper
Pedestrian simulations have many uses, from pedestrian planning for architecture design through to games and entertainment. However, it is still challenging to efficiently author such simulations, especially for non-technical users. Direct pedestrian control is usually laborious, and, while indirect, environment-level control is often faster, it cu...
Conference Paper
The use of a terrestrial laser scanner (TLS) has become a popular technique for the acquisition of 3D scenes in the fields of cultural heritage and archaeology. In this study, a semi-automatic reconstruction technique is presented to convert the point clouds that are produced, which often contain noise or are missing data, into a set of triangle me...
Conference Paper
Full-text available
The intelligibility of visual speech can be affected by a number of facial visual signals, e.g. lip emphasis, teeth and tongue visibility, and facial hair. This paper focuses on lip visibility. In the study presented in this paper, we use spectrally-distorted speech to train groups of non-native, English-speaking Saudi listeners using three differe...
Conference Paper
Demand for high performance road network simulation is increasing due to the need for improved traffic management to cope with the globally increasing number of road vehicles and the poor capacity utilisation of existing infrastructure. This paper demonstrates FLAME GPU as a suitable Agent Based Simulation environment for road network simulations,...
Article
OneClick is a user-friendly web-based program, developed specifically for quick-and-easy design of focused mutagenesis experiments (e.g., site-directed mutagenesis and saturation mutagenesis). Written in Perl and developed into a web application using CGI programming, OneClick offers a step-by-step experimental design, from mutagenic primer design...
Article
Physically-based animation techniques enable more realistic and accurate animation to be created. We present a fully physically-based approach for efficiently producing realistic-looking animations of facial movement, including animation of expressive wrinkles. This involves simulation of detailed voxel-based models using a graphics processing unit...
Article
Physically-based animation techniques enable more realistic and accurate animation to be created. Such approaches require the creation of a complex simulation model that, for computer graphics applications, can efficiently produce realistic-looking animations. We present a process to automatically create animatable nonconforming hexahedral finite e...
Conference Paper
Full-text available
This work applies a viseme-driven talking head in a pronunciation training system. The aim is to create a pronunciation assistant to complement traditional methods and to assist the work of a human language tutor. Visual speech can be valuable in speech tutoring applications because vision benefits human speech perception, for three reasons as sugg...
Conference Paper
Full-text available
We present a technique for simulating accurate physically modelled acoustics within an outdoor urban environment and a tool that presents the acoustics alongside a visually rendered counterpart. Acoustic modelling is achieved by using a mixture of simulating ray-traced specular sound wave reflections and applying radiosity to simulate diffuse refle...
Conference Paper
We present a method for extracting skull and face models from MRI datasets and show how the resulting dataset is used in a craniofacial reconstruction (CFR) system. Datasets for 60 individuals are used to produce a database of 3D skull-face models, which are then used to give faces to unknown skulls. In addition to the skull-face geometry, other in...
Conference Paper
Full-text available
This paper presents a novel approach to creating 3D facial animation using a sketch-based interface where the animation is generated by interpolating a sequence of sketched key poses. The user does not need any knowledge of the underlying mechanism used to create different expressions or facial poses, and no animation controls or parameters are dir...
Conference Paper
Full-text available
A common approach to producing visual speech is to interpolate the parameters describing a sequence of mouth shapes, known as visemes, where visemes are the visual counterpart of phonemes. A single viseme typically represents a group of phonemes that are visually similar. Often these visemes are based on the static poses used in producing a phoneme...
Conference Paper
Full-text available
This paper introduces a three-dimensional virtual head for use in speech tutoring applications. The system achieves audiovisual speech synthesis using viseme-driven animation and a coarticulation model, to automatically generate speech from text. The talking head was evaluated using a modified rhyme test for intelligibility. The audiovisual speech...
Article
Full-text available
We present an accurate and efficient method to generate samples based on a Poisson-disk distribution. This type of distribution, because of its blue noise spectral properties, is useful for image sampling. It is also useful for multidimensional Monte Carlo integration and as part of a procedural object placement function. Our method extends trivial...
Article
Full-text available
This study describes the learning potential of serious games and their success in a number of domains such as the military, healthcare, education, and emergency services. The work aims to highlight the training opportunities available for serious games in the police domain in general, and in the Dubai police force in particular, and the challenges...
Article
Full-text available
A method for ray casting implicit surfaces, defined with procedural noise models, is presented. The method is robust in that it is able to guarantee correct intersections at all image pixels and for all types of implicit surfaces. This robustness comes from the use of an affine arithmetic representation for the quantity that expresses the variation...
Article
Full-text available
Hypertextures are a useful modelling tool in that they can add three-dimensional detail to the surface of otherwise smooth objects. Hypertextures can be rendered as implicit surfaces, resulting in objects with a complex but well defined boundary. However, representing a hypertexture as an implicit surface often results in many small parts being det...
Conference Paper
Faces can be modelled using a number of techniques. Existing faces can be transferred to a digital form using equipment such as laser scanners. New faces can be constructed using commercial modelling tools, or using specialist software, e.g. Photo-fit software. We present a technique that can create a 3D head using intuitive 2D sketching techniques...
Conference Paper
Full-text available
Terrains for computer graphics have traditionally been modelled with height fields. In the case of procedurally defined terrains, the height field is generated by a displacement map z = f(x,y). Displacement maps, however, do not allow the formation of such terrain features as overhangs, arches or caves. The most flexible approach to model procedura...
Conference Paper
A method is presented to extract the outline of the skull region in coronal Magnetic Resonance (MR) images from the Visible Human Project. The starting point is the formulation of a Gradient Vector Flow (GVF) snake extended to include statistical shape information. This method exploits the diffusion process used by the GVF snake and improves its ca...
Article
Full-text available
A common approach to produce visual speech is to interpolate the parameters describing a sequence of mouth shapes, known as visemes, where a viseme corresponds to a phoneme in an utterance. The interpolation process must consider the issue of context-dependent shape, or coarticulation, in order to produce realistic-looking speech. We describe an ap...
Article
Full-text available
Game assets are portable between games. The games themselves are, however, dependent on the game engine they were developed on. Middleware has attempted to address this by, for instance, separating out the AI from the core game engine. Our work takes this further by separating the game from the game engine, and making it portable between game engi...
Chapter
Full-text available
The design of serious games based on sound learning and instructional principles is important to ensure learning is integrated in the ‘game-play’. However, the process of achieving this is not yet fully understood, and research is hampered by the lack of practical demonstrations of how effective instructional design is when used alongside game desi...
Chapter
Visualising implicit surfaces with the ray casting method is a slow procedure. The design cycle of a new implicit surface is, therefore, fraught with long latency times as a user must wait for the surface to be rendered before being able to decide what changes should be introduced in the next iteration. In this paper, we present an attempt at reduc...
Article
Full-text available
The visualisation of implicit surfaces can be an inefficient task when such surfaces are complex and highly detailed. Visualising a surface by first converting it to a polygon mesh may lead to an excessive polygon count. Visualising a surface by direct ray casting is often a slow procedure. In this paper we present a progressive refinement renderer...
Article
In this paper we show how the expensive, offline dynamic simulations of character motions can be approximated using the cheaper weighted inverse kinematics (WIK)-based approach. We first show how a dynamics-based approach can be used to produce a motion that is representative of a real target actor using the motion of a different source actor and t...
Conference Paper
Creating faces is important in a number of application areas. Faces can be constructed using commercial mod-elling tools, existing faces can be transferred to a digital form using equipment such as laser scanners, and law enforcement agencies use sketch artists and photo-fit software to produce faces of suspects. We present a tech-nique that can cr...
Conference Paper
Hypertextures are a useful modelling tool in that they can add three-dimensional detail to the surface of otherwise smooth objects. Hypertextures can be rendered as implicit surfaces, resulting in objects with a complex but well defined boundary. However, representing a hypertexture as an implicit surface often results in many small parts being det...
Article
Full-text available
A method is presented for ray casting implicit surfaces defined by fractal combinations of procedural noise functions. The method is robust and uses affine arithmetic to bound the variation of the implicit function along a ray. The method is also efficient due to a modification in the affine arithmetic representation that introduces a condensation...
Conference Paper
Skinning is the name given to the technique whereby a polygon skin is derived from an underlying articulating skeleton. We reverse this process, starting with a collection of points positioned on the surface of a character and then generating an underlying skeleton using a constrained optimisation approach. We call this inverse skinning. The surfac...