2007 - EG UK Theory and Practice of Computer Graphics

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    Visualization Notations, Models and Taxonomies
    (The Eurographics Association, 2007) Brodlie, Ken; Noor, Nurul Mohd; Ik Soo Lim and David Duce
    Visualization taxonomies are an important means of imposing some structure on a rather diverse field. We review some earlier work in this area, particularly work based on the use of a notation to label classes of visualization techniques that are appropriate to particular entities. We propose a new notation introducing it in the context of a new visualization reference model, one we hope will lead eventually to a means of describing visualizations in a clear and unambiguous way.
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    Towards Individualized Ageing Functions for Human Face Images
    (The Eurographics Association, 2007) Hunter, David W.; Tiddeman, Bernard P.; Ik Soo Lim and David Duce
    We present an overview of work in progress to create ageing functions for the transformation of human face images. Our aims are twofold; Firstly, by extension to three dimensions, the problems of pose and lighting associated with photographs can be eliminated, and the shape changes associated with ageing modelled more accurately. Secondly, by using multi-variate statistical methods that can take individuality into account, the correlations between appearance and type of ageing can be learned and the most appropriate one automatically selected.
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    Seamless Mesh Stitching Using Curve Approximation
    (The Eurographics Association, 2007) Gobeawan, Like; Xu, Shuhong; Turner, Stephen John; Ik Soo Lim and David Duce
    Stitching two mesh partitions at their boundaries poses some challenges, especially when a visually seamless result is desired. In general, direct stitching of mismatching mesh boundaries does not readily produce a seamless result, unless some geometric measures are considered in the process. In this paper, a novel stitching technique for mesh partitions with mismatching boundaries is proposed. Using the boundary information of the mesh partitions, smooth curves are constructed across the partition boundaries and new vertices along the stitch path are generated to replace the mismatching boundary vertices. Several seamlessness criteria are considered in the construction of the algorithm to ensure a seamless stitch result.
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    Perception-Based Lighting-by-Example
    (The Eurographics Association, 2007) Ha, Hai Nam; Olivier, Patrick; Ik Soo Lim and David Duce
    In computer graphics, easy-to-use tools for configuring lighting for 3D scenes are required by users. Following a perception-based lighting design framework, which models image quality using cognitively inspired objective functions, we present a new approach to lighting design which both: (1) allows the declarative specification of lighting; and (2) uses target scenes and images to facilitate intuitive and natural interactive control of the scene lighting. The LightOPex system enables users to select the desired lighting for a scene using exemplars in the form of 3D scenes and 2D images and uses the perceptual properties of these exemplars as target values in an initial optimization step.
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    A Distance Hierarchy to Detect Collisions Between Deformable Objects
    (The Eurographics Association, 2007) Madera, Francisco A.; Day, Andy M.; Laycock, Stephen D.; Ik Soo Lim and David Duce
    To detect collisions between deformable objects we introduce an algorithm that computes the closest distances between certain feature points defined in their meshes. The strategy is to divide the objects into regions and to define a representative vertex that serves to compute the distance to the regions of the other objects. Having obtained the closest regions between two objects, we proceed to explore these regions by expanding them and detecting the closest sub-regions. We handle a hierarchy of regions and distances where the first level contains n1 regions, each one is divided into n2 sub-regions, and so on. A collision is obtained when the distance between two vertices in the last level of the tree is less than a predefined value e. The advantage of our algorithm is that we can follow the deformation of the surface with the representative vertices defined in the hierarchy.
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    An Immersive Granular Material Visualization System with Haptic Feedback
    (The Eurographics Association, 2007) Dorjgotov, Enkhtuvshin; Benes, Bedrich; Madhavan, Krishna; Ik Soo Lim and David Duce
    Recent advances in distributed virtual reality systems and haptic technologies provide new opportunities to augment human sense of touch into highly complex and immersive visual simulations. Haptic feedback further enhances human immersion into virtual environments. We present techniques for portable and distributed rendering of real-time active and passive stereo views of virtual granular material that allow real-time haptic interaction and visualization. The main goal of the research was to develop highly portable and immersive virtual reality system that provides intuitive haptic interactions between a user and the granular material in several VR configurations. We developed real-time haptic enabled virtual sand rendering system for high-end VR systems, a FLEX (CAVETM-like display from Fakespace Systems), a high resolution tiled-wall display, comparatively low cost portable VR system that consists of two projectors with two horizontally and vertically polarizing filters, and the Disney projection screen. Our system has a distributed rendering architecture where a server computer is dedicated to haptic interaction force rendering and client computers are dedicated to a visual rendering of granular surface. Interconnection between the haptic and visual rendering programs is realized through a stream based TCP/IP communication. We report the architecture and implementation details of this highly portable and haptic force feedback enabled virtual reality system for interactive granular surface manipulation in this paper.
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    A Novel Control Mechanism for Distributed Stream Rendering
    (The Eurographics Association, 2007) O'Brien, J. T.; Kalawsky, R. S.; Ik Soo Lim and David Duce
    This paper describes a new control mechanism for distributed rendering. Control mechanisms have previously been widely used in many fields from autonomous robots to video streaming. Their use in video streaming has allowed quality-of-service, user orientated, transmission of videos across changing transport networks. We show how control mechanisms can be applied to distributed rendering to provide responsive, user orientated visualisa- tions. The control mechanisms are implemented as an extension of Chromium, a stream processing framework for OpenGL. The system should also be applicable to other stream based render systems with a significant benefit. The new system allows distributed rendering to be modularised into specialist units that self organise work load to meet the demands of the user.
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    Level of Detail for Physically Based Fire
    (The Eurographics Association, 2007) Gundersen, Odd Erik; Tangvald, Lars; Ik Soo Lim and David Duce
    In this paper, we propose a framework for implementing level of detail for a physically based fire rendering running on the GPU. The physics of the fire is simulated using a fluid solver and combustion modelling, and the fire is visualised using a particle system. Our preliminary results indicate that by adjusting the simulation domain and particle system, performance can be increased without noticeably degrading the fire visually when it is far from the camera.
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    A Statistically-Assisted Sketch-Based Interface for Creating Arbitrary 3-dimensional Faces
    (The Eurographics Association, 2007) Gunnarsson, Orn; Maddock, Steve; Ik Soo Lim and David Duce
    Creating faces is important in a number of application areas. Faces can be constructed using commercial modelling 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 technique that can create a 3-dimensional head using intuitive, artistic 2-dimensional sketching techniques. Our work involves bringing together two types of graphics applications: sketching interfaces and systems used to create 3-dimensional faces, through the mediation of a statistical model. We present our results where we sketch a nose and search for a geometric face model in a database whose nose best matches the sketched nose.
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    Real-time Fluid Simulation Coupled with Cloth
    (The Eurographics Association, 2007) Harada, Takahiro; Koshizuka, Seiichi; Kawaguchi, Yoichiro; Ik Soo Lim and David Duce
    This paper presents a real-time simulation method for coupling of cloth and fluids computed by using Smoothed Particle Hydrodynamics (SPH). To compute interaction between cloth consisting of several polygons and fluid particles, the distance between cloth to the particle have to be calculated. It is computationally expensive because we have to compute the distance to the faces, edges and vertices of polygons. Instead of calculating the exact distance to a cloth, we calculate an approximate distance by using the distance to the faces and the gravitational centers of the polygons. This paper also presents techniques to perform the coupled simulation entirely on Graphics Processing Units (GPUs). The computation of interaction forces is divided into fluid-cloth and cloth-fluid forces to implement entire simulation on GPUs. By exploiting the parallelizm of GPUs, we could couple simulations of several tens of thousands of fluid particles and cloth which consists of several thousands of polygons in real-time.
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    Viewing 0.3Tb Heart Simulation Data At Your Desk
    (The Eurographics Association, 2007) Grimstead, I. J.; Kharche, S.; Zhang, H.; Avis, N. J.; Walker, D. W.; Ik Soo Lim and David Duce
    Atrial fibrillation (AF) affects a large section of the aged population, accounting for nearly 1% of total National Health Service (NHS) expenditure. Modelling of this condition to promote further understanding is hence of extreme importance to the NHS. Such modelling takes considerable compute power, producing large datasets; for instance, an 18 million data point model produces 0.3Tb when simulating 3 seconds of heart activity. Such large datasets are currently batch processed to produce a movie from a preset camera position. What is needed is a means of reducing the data to a more manageable size, where it can be displayed in real-time at the heart modeller s desk for interactive exploration and evaluation. We present a pilot study where the Resource-Aware Visualization Environment (RAVE) has been adapted to filter AF datasets ready for subsequent interactive visualization on a desktop machine. A high-end visualization workstation was not required to view the 0.3Tb dataset in real-time, where the modeller could manipulate both camera position/orientation and simulated elapsed time at interactive rates. This has enabled visual inspection and related rapid evaluation of AF, as well as supporting intuitive insight.
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    Bifocal Radial Visualization of Intranet Search Results using Image Caching
    (The Eurographics Association, 2007) Zschimmer, Andreas J.; Roberts, Jonathan C.; Ik Soo Lim and David Duce
    This paper presents a novel image caching strategy implemented for our bifocal radial visualization for Intranet search visualization. This visualization displays search results by combining hierarchical information with focus+ context. It is designed specifically for domain or Intranet searches, where specific search results are overlaid (highlighted) on top of a hierarchical circular visualization, which enables these results to be viewed in context with the whole dataset. Drawing large hierarchies is time-consuming, hence the main visualization is cached in a unique way to provide interactive visualization and manipulation. The caching is complicated by the use of the bifocal distortion where a portion of the visualization is magnified, thus two sets of images are cached. This paper describes the caching technique in detail.
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    Scanline Edge-flag Algorithm for Antialiasing
    (The Eurographics Association, 2007) Kallio, Kiia; Ik Soo Lim and David Duce
    In this paper, a novel algorithm for rendering antialiased 2D polygons is presented. Although such algorithms do exist, they are inefficient when comparing to non-antialiased alternatives. This has lead to a situation where the developers and the end users of the applications need to make a choice between high speed and high quality. The algorithm presented here however equals the performance of an industry standard non-antialiased polygon filling algorithm, while providing good antialiasing quality. Furthermore, the algorithm addresses the requirements of a modern 2D rendering API by supporting features such as various fill rules. Most of the research in antialiased 2D rendering has been proprietary work, and there is very little documentation about the algorithms in the literature. This paper brings an update to the situation by providing a thorough explanation of one such algorithm.
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    Adaptive Infrastructure for Visual Computing
    (The Eurographics Association, 2007) Brodlie, K. W.; Brooke, J.; Chen, M.; Chisnall, D.; Hughes, C. J.; John, Nigel W.; Jones, M. W.; Riding, M.; Roard, N.; Turner, M.; Wood, J. D.; Ik Soo Lim and David Duce
    Recent hardware and software advances have demonstrated that it is now practicable to run large visual computing tasks over heterogeneous hardware with output on multiple types of display devices. As the complexity of the enabling infrastructure increases, then so too do the demands upon the programmer for task integration as well as the demands upon the users of the system. This places importance on system developers to create systems that reduce these demands. Such a goal is an important factor of autonomic computing, aspects of which we have used to influence our work. In this paper we develop a model of adaptive infrastructure for visual systems. We design and implement a simulation engine for visual tasks in order to allow a system to inspect and adapt itself to optimise usage of the underlying infrastructure. We present a formal abstract representation of the visualization pipeline, from which a user interface can be generated automatically, along with concrete pipelines for the visualization. By using this abstract representation it is possible for the system to adapt at run time. We demonstrate the need for, and the technical feasibility of, the system using several example applications.
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    Anatomy Education using Rapid Prototyping
    (The Eurographics Association, 2007) Thomas, Rhys G.; John, Nigel W.; Lim, Ik Soo; Ik Soo Lim and David Duce
    Rapid Prototyping is a technique which is rapidly gaining interest amongst the medical community for many different purposes. In this paper we present a novel tool that uses rapidly prototyped models to serve as an interaction device for the teaching of anatomy. The user interacts with volume data of real human organs in an Augmented Reality environment delivered via a Head-Mounted Display. We include a description of how all of the key parts of the system operate and describe their integration. Our hypothesis is that this approach provides an effective and compelling alternative to cadaver based anatomy education.
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    A Case-Study of Inconsistent Surface Reconstruction in Recent Literature Resulting from Octree Rotation-Variance
    (The Eurographics Association, 2007) Hughes, David Meirion; Lim, Ik Soo; Ik Soo Lim and David Duce
    We review the use of octree and PCA (Principle Component Analysis) in current literature and explore a leading piece of research, as a case study, to highlight how overlooking octree rotation-variance has resulted in inconsistent results. We provide a simple method using PCA to re-orientate an octree to the intrinsic-orientation defined by data variance. In our case-study we explore and provide a method for consistency within multi-scale CSRBFs (Compactly Supported Radial Basis Functions). By utilizing PCA we provide rotation-invariant multi-scale surface reconstructions. We show, by curvature analysis, that the original surface reconstruction method is variant to data orientation and that our approach results in rotation-invariant reconstructions. In addition we also provide a technique for more flexibility when choosing a CSRBF for use with multi-scale surface reconstruction.
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    Interval-Based Motion Blending for Hand Grasping
    (The Eurographics Association, 2007) Brisbin, Matt; Benes, Bedrich; Ik Soo Lim and David Duce
    For motion to appear realistic and believable proper motion blending methods must be used in respect to the goal or task at hand. We present a method that extends the theory of move trees [MBC01] by tagging (attaching) information to each clip within a database at intervals and finding the shortest distance per tag while pruning the tree using convergence priority. Our goal is to retain the physical characteristics of motion capture data while using non-destructive blending in a goal-based scenario. With the intrinsically high dimensionality of a human hand our method also is concerned with intelligent pruning of the move tree. By constructing a move tree for hand grasping scenarios that is sampled per interval within clips and adheres to a convergence priority; we plan to develop a method that will autonomously conform a hand to the object being g
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    Simulating Film Grain using the Noise-Power Spectrum
    (The Eurographics Association, 2007) Stephenson, Ian; Saunders, Arthur; Ik Soo Lim and David Duce
    Film grain is an essential part of real images. The artifacts it introduces add character to images, which can otherwise appear too perfect. This paper considers the synthesis of film grain based upon its noise-power spectrum, producing grain fields which approximate real film over a range of enlargements and densities. We also identify limitations of the noise-power spectrum in that it fails to fully characterize grain. Simulated grain fields have spectra which match real grain, but lack the phase and density correlations required to create the appearance of individual grains at high magnifications.
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    A Flexible Approach to High Performance Visualization Enabled Augmented Reality
    (The Eurographics Association, 2007) Hughes, Chris J.; John, Nigel W.; Ik Soo Lim and David Duce
    Commonly registration and tracking within Augmented Reality (AR) applications have been built around computer vision techniques that use limited bold markers, which allow for their orientation to be estimated in real-time. All attempts to implement AR without specific markers have increased the computational requirements and some information about the environment is still needed. In this paper we describe a method that not only provides a flexible platform for supporting AR but also seamlessly deploys High Performance Computing (HPC) resources to deal with the additional computational load, as part of the distributed High Performance Visualization (HPV) pipeline used to render the virtual artifacts. Repeatable feature points are extracted from known views of a real object and then we match the best stored view to the users viewpoint using the matched feature points to estimate the objects pose. We also show how our AR framework can then be used in the real world by presenting a markerless AR interface for Transcranial Magnetic Stimulation (TMS).
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    A 3D Visualisation Environment Modelling the Evolution of North-West Europe since the Last Glacial Maximum
    (The Eurographics Association, 2007) Wainwright, Adam; Varsamidis, Thomas; Scourse, James; Ik Soo Lim and David Duce
    This work in progress aims to provide an interactive 3D visualisation allowing real time manipulation of glacial isostatic adjustment (GIA) model output data which reconstructs the ice distribution and coastline position in north-west Europe since the Last Glacial Maximum (LGM). The Lambeck GIA model is the current state of the art for European ice sheet and shoreline modelling and the work presented applies scientific visualisation techniques to an area of earth and ocean science that to date has not benefited from such technologies. The end application aims to eventually provide a real-time interactive 3D virtual world for scientists to explore the reconstruction data through direct manipulation. A recent study uses the Lambeck data as a basis for shelf sea palaeotidal reconstructions with profound implications for the environment, ecology and carbon cycle as the climate of northwest Europe has developed since the LGM. As the latter has only been seen in digital image form to date, the work of this project innovates by providing further user interaction, data interpretation and extraction from the GIA and palaeotidal models.