Constrained parameterization with applications to graphics and image processing.

Surface parameterization is to establish a transformation that maps the points on a surface to a specified parametric domain. It has been widely applied to computer graphics and image processing fields. The challenging issue is that the usual positional constraints always result in triangle flipping in parameterizations (also called foldovers). Additionally, distortion is inevitable in parameterizations. Thus the rigid constraint is always taken into account. In general, the constraints are application-dependent. This thesis thus focuses on the various constraints depended on applications and investigates the foldover-free constrained parameterization approaches individually. Such constraints usually include, simple positional constraints, tradeoff of positional constraints and rigid constraint, and rigid constraint. From the perspective of applications, we aim at the foldover-free parameterization methods with positional constraints, the as-rigid-as-possible parameterization with positional constraints, and the well-shaped well-spaced pre-processing procedure for low-distortion parameterizations in this thesis. The first contribution of this thesis is the development of a RBF-based re-parameterization algorithm for the application of the foldover-free constrained texture mapping. The basic idea is to split the usual parameterization procedure into two steps, 2D parameterization with the constraints of convex boundaries and 2D re-parameterization with the interior positional constraints. Moreover, we further extend the 2D re-parameterization approach with the interior positional constraints to high dimensional datasets, such as, volume data and polyhedrons. The second contribution is the development of a vector field based deformation algorithm for 2D mesh deformation and image warping. Many presented deformation approaches are used to employ the basis functions (including our proposed RBF-based re-parameterization algorithm here). The main problem is that such algorithms have infinite support, that is, any local deformation always leads to small changes over the whole domain. Our presented vector field based algorithm can effectively carry on the local deformation while reducing distortion as much as possible. The third contribution is the development of a pre-processing for surface parameterization. Except the developable surfaces, the current parameterization approaches inevitably incur large distortion. To reduce distortion, we proposed a pre-processing procedure in this thesis, including mesh partition and mesh smoothing. As a result, the resulting meshes are partitioned into a set of small patches with rectangle-like boundaries. Moreover, they are well-shaped and well-spaced. This pre-processing procedure can evidently improve the quality of meshes for low-distortion parameterizations

Texture and Colour in Image Analysis

Research in colour and texture has experienced major changes in the last few years. This book presents some recent advances in the field, specifically in the theory and applications of colour texture analysis. This volume also features benchmarks, comparative evaluations and reviews

Mining subsidence: its effects on the South-East Fife coastline, Scotland

This thesis is concerned with the impact of coal mining activities upon the coastal zone of southeast Fife. Coastal changes over a 100 year period from 1894 to 1996 have been evaluated by determining the plan variation of the High Water and Low Water datum recorded on different editions of large scale Ordnance Survey (O.S.) Plans of the area. Deposition and erosion implied by the movement of the tidal datum are related to the longshore dispersal of spoil deposition from the coastal bings (1) and to mining subsidence. Mining subsidence is evaluated using the Surface Deformation Prediction System (SDPS), previously used at sites in the United States, and now applied for the first time to a United Kingdom coalfield. A new technique is developed that enables the subsidence values to be generated along O.S. co-ordinates at 10m intervals. Subsidence values are recorded with an accuracy of ±20% along the tidal marks of 1894, 1914, 1960, 1994 and 1996. Between Buckhaven and Dysart the coastline is found to have subsided with only small pockets having been left unaffected. Indeed, in the West Sands Bay area a subsidence trough with a maximum of 5.7+l.lm is calculated. The extent of recent coastal erosion along the shore can be seen to correlate with predicted subsidence over different mining panels and thus confirms the importance of this factor upon the coastal process in south-east Fife. These results are reinforced by comparing bench-mark heights against subsidence values producing a correlation coefficient of 0.9. The state of the pre-mining coastline is evaluated using historic documents and photographs. This provides a starting point for evaluating the changes wrought on the coastline by the large scale mining activities which commenced about 1898 and terminated with the closure of the Frances colliery in 1984. Following this, the extent of coastal change from the analysis of O.S Plans is presented. Subsequent chapters evaluate the possible factors which may have caused the observed coastal changes including long term changes, land uplift or subsidence following the last glaciation, mining activities and possible sea level changes due to global warming. To ensure the greatest possible accuracy in the determination of coastal changes against subsidence data a rigorous GIS is employed to analyse both map and mining data allowing for registrations to be obtained between the different surveys. This involves the manipulation of both vector and raster data from the O.S. plans and the SDPS software requiring the laborious and lime consuming transfer of data between different computer platforms. Despite this caveat this novel method is demonstrated, in the thesis, to be a flexible and precise method which can be applied to any given site for the accurate prediction of mining subsidence. 1: Bing is the Scottish phrase for slag heap

Appearance Modelling and Reconstruction for Navigation in Minimally Invasive Surgery

Minimally invasive surgery is playing an increasingly important role for patient care. Whilst its direct patient benefit in terms of reduced trauma, improved recovery and shortened hospitalisation has been well established, there is a sustained need for improved training of the existing procedures and the development of new smart instruments to tackle the issue of visualisation, ergonomic control, haptic and tactile feedback. For endoscopic intervention, the small field of view in the presence of a complex anatomy can easily introduce disorientation to the operator as the tortuous access pathway is not always easy to predict and control with standard endoscopes. Effective training through simulation devices, based on either virtual reality or mixed-reality simulators, can help to improve the spatial awareness, consistency and safety of these procedures. This thesis examines the use of endoscopic videos for both simulation and navigation purposes. More specifically, it addresses the challenging problem of how to build high-fidelity subject-specific simulation environments for improved training and skills assessment. Issues related to mesh parameterisation and texture blending are investigated. With the maturity of computer vision in terms of both 3D shape reconstruction and localisation and mapping, vision-based techniques have enjoyed significant interest in recent years for surgical navigation. The thesis also tackles the problem of how to use vision-based techniques for providing a detailed 3D map and dynamically expanded field of view to improve spatial awareness and avoid operator disorientation. The key advantage of this approach is that it does not require additional hardware, and thus introduces minimal interference to the existing surgical workflow. The derived 3D map can be effectively integrated with pre-operative data, allowing both global and local 3D navigation by taking into account tissue structural and appearance changes. Both simulation and laboratory-based experiments are conducted throughout this research to assess the practical value of the method proposed

Spatial peripheral interaction techniques for viewing and manipulating off-screen digital content

When an information space is larger than the display, it is typical for interfaces to only support interacting with content that is rendered within its viewport. To support interacting with off-screen content, our work explores the design and evaluation of several spatial off-screen exploration techniques that make use of the interaction space around the display. These include Paper Distortion, Dynamic Distortion, Dynamic Peephole Inset, Spatial Panning, and Point2Pan. We also contribute a formalized descriptive framework of the off-screen interaction space that divides the around-device space into interaction volumes and analyzes them based on different factors. This framework guided the design of an off-screen interaction system, called Off-Screen Desktop, which implemented our spatial techniques using consumer-level motion sensing hardware. To enable a more detailed analysis of spatial interaction systems, we also developed a web-based visualization system, called SpatialVis, that visualizes log data over a video screen capture of the associated user interface

Reproduction of Historic Costumes Using 3D Apparel CAD

The progress of digital technology has brought about many changes. In the world of fashion, 3D apparel CAD is attracting attention as the most promising product which reduces time and cost in the design process through virtual simulation. This study highlights the potential of its technology and tries to extend the boundaries of its practical use through the simulation of historical dresses. The aim of this study is to identify the desirable factors for digital costume development, to produce accurate reproductions of digital clothing from historical sources and to investigate the implications of developing it for online exhibitory and educational materials. In order to achieve this, this study went through following process. First, the theoretical background of the digital clothing technology, 3D apparel CAD and museum and new media was established through the review of various materials. Second, the desirable concepts for effective digital costume were drawn from the analysis of earlier digital costume projects considering the constraints of costume collections and limitations of the data on museum websites: faithful reproduction, virtual fabrication and Interactive and stereographic display. Third, design development was carried out for the embodiment of the concepts based on two costumes in the Museum of London: (1) preparation which provided foundation data with physical counterparts, (2) digital reproduction which generated digital costumes with simulations and (3) application development where simulations were embodied into a platform. Fourth, evaluation of the outcomes was carried with different groups of participants. The evaluation results indicated that the outcomes functioned as an effective information delivery method and had suitability and applicability for exhibitory and educational use. However, further improvement particularly in the faithfulness of current digital costumes and more consideration for the concerns for virtual and intangible nature were pointed out to be required. Nevertheless digital costumes were reviewed to bring notable benefits in complete or partial replacement of the relics, presentation of invisible features, release of physical constraints on appreciation and provision of integrated and comprehensive information. This study expects that use of digital costumes may assist museums in terms of preservation, documentation and exhibition of costume collections giving new possibility especially to the endangered garments lying in the dark

An efficient active B-spline/nurbs model for virtual sculpting

This thesis presents an Efficient Active B-Spline/Nurbs Model for Virtual Sculpting. In spite of the on-going rapid development of computer graphics and computer-aided design tools, 3D graphics designers still rely on non-intuitive modelling procedures for the creation and manipulation of freeform virtual content. The ’Virtual Sculpting' paradigm is a well-established mechanism for shielding designers from the complex mathematics that underpin freeform shape design. The premise is to emulate familiar elements of traditional clay sculpting within the virtual design environment. Purely geometric techniques can mimic some physical properties. More exact energy-based approaches struggle to do so at interactive rates. This thesis establishes a unified approach for the representation of physically aware, energy-based, deformable models, across the domains of Computer Graphics, Computer-Aided Design and Computer Vision, and formalises the theoretical relationships between them. A novel reformulation of the computer vision approach of Active Contour Models (ACMs) is proposed for the domain of Virtual Sculpting. The proposed ACM-based model offers novel interaction behaviours and captures a compromise between purely geometric and more exact energy-based approaches, facilitating physically plausible results at interactive rates. Predefined shape primitives provide features of interest, acting like sculpting tools such that the overall deformation of an Active Surface Model is analogous to traditional clay modelling. The thesis develops a custom-approach to provide full support for B-Splines, the de facto standard industry representation of freeform surfaces, which have not previously benefited from the seamless embodiment of a true Virtual Sculpting metaphor. A novel generalised computationally efficient mathematical framework for the energy minimisation of an Active B-Spline Surface is established. The resulting algorithm is shown to significantly reduce computation times and has broader applications across the domains of Computer-Aided Design, Computer Graphics, and Computer Vision. A prototype ’Virtual Sculpting’ environment encapsulating each of the outlined approaches is presented that demonstrates their effectiveness towards addressing the long-standing need for a computationally efficient and intuitive solution to the problem of interactive computer-based freeform shape design

Virtual Reality Games for Motor Rehabilitation

This paper presents a fuzzy logic based method to track user satisfaction without the need for devices to monitor users physiological conditions. User satisfaction is the key to any product’s acceptance; computer applications and video games provide a unique opportunity to provide a tailored environment for each user to better suit their needs. We have implemented a non-adaptive fuzzy logic model of emotion, based on the emotional component of the Fuzzy Logic Adaptive Model of Emotion (FLAME) proposed by El-Nasr, to estimate player emotion in UnrealTournament 2004. In this paper we describe the implementation of this system and present the results of one of several play tests. Our research contradicts the current literature that suggests physiological measurements are needed. We show that it is possible to use a software only method to estimate user emotion

MediaSync: Handbook on Multimedia Synchronization

This book provides an approachable overview of the most recent advances in the fascinating field of media synchronization (mediasync), gathering contributions from the most representative and influential experts. Understanding the challenges of this field in the current multi-sensory, multi-device, and multi-protocol world is not an easy task. The book revisits the foundations of mediasync, including theoretical frameworks and models, highlights ongoing research efforts, like hybrid broadband broadcast (HBB) delivery and users' perception modeling (i.e., Quality of Experience or QoE), and paves the way for the future (e.g., towards the deployment of multi-sensory and ultra-realistic experiences). Although many advances around mediasync have been devised and deployed, this area of research is getting renewed attention to overcome remaining challenges in the next-generation (heterogeneous and ubiquitous) media ecosystem. Given the significant advances in this research area, its current relevance and the multiple disciplines it involves, the availability of a reference book on mediasync becomes necessary. This book fills the gap in this context. In particular, it addresses key aspects and reviews the most relevant contributions within the mediasync research space, from different perspectives. Mediasync: Handbook on Multimedia Synchronization is the perfect companion for scholars and practitioners that want to acquire strong knowledge about this research area, and also approach the challenges behind ensuring the best mediated experiences, by providing the adequate synchronization between the media elements that constitute these experiences