2007 - EG UK Theory and Practice of Computer Graphics

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https://diglib.eg.org/handle/10.2312/902

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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.
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.
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.
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.
Delivering Effective and Usable Interactive 3D Visualization on Lightweight Mobile Devices
(The Eurographics Association, 2007) Holmes, I. R.; Kalawsky, R. S.; Ik Soo Lim and David Duce
3D visualization has significantly enhanced scientists ability to discover important new insights into their data. In this paper we focus specifically on associated HCI and human factors of remote 3D visualization. We discuss how, through adopting a user-centered design approach we have successfully engineered the Lightweight Visualization software system. This exciting HCI innovation has enabled scientists to interact with their own 3D visualization packages whenever they want and from wherever they happen to be. We describe how this advanced level of on the move HCI was achieved by facilitating scientists to interact with their familiar desk-based 3D user interfaces via affordable, wireless computing devices. In particular, we highlight how the system has initially been employed within the UK e-Science RealityGrid project to support an extensively used 3D molecular dynamics user interface on the roaming, handheld PDA. Whilst it is recognized that these types of lightweight devices possess limited compute, graphics and memory capability we also identify how Lightweight Visualization has overcome these serious limitations to effectively deliver usable interactive 3D visualization on the commodity mobile platform.
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
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.
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.
Streaming and Data Enrichment
(The Eurographics Association, 2007) McDerby, Mary J.; Hewitt, William T.; Turner, Martin J.; Ik Soo Lim and David Duce
Data is being created at a continuously increasing rate. Scientists are drowning in their data . So much so they cannot visualize the data to see the big picture. This work-in-progress paper describes a data capture and visualization problem, and the steps being undertaken to solve the problem. An overview is given of the various approaches to dealing with these large data sets that have been previously proposed and the application of such methods within a well known scientific visualization tool. The paper then goes on to propose a method that deals with large data visualization by addressing the bottlenecks in the visualization pipeline, and combining some of the approaches described herein with parallel techniques on a high performance visualization system.
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.
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.
MTCut: GPU-based Marching Tetra Cuts
(The Eurographics Association, 2007) Monclus, Eva; Navazo, Isabel; Vazquez, Pere-Pau; Ik Soo Lim and David Duce
Isosurface construction and rendering based on tetrahedral grids has been adequately implemented on programmable graphics hardware. In this paper we present MTCut: a volume cutting algorithm that is able to cut isosurfaces obtained by a Marching Tetrahedra algorithm on volume data. It does not require a tetrahedal representation and runs in real time for complex meshes of up to 1.8M triangles. Our algorithm takes as input the isosurface to be cut, and produces the cut geometry in response to the user interaction with a haptic device. The result is a watertight manifold model that can be interactively recovered back to CPU upon user request.
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.
Steering Chemistry in the Right Direction!
(The Eurographics Association, 2007) Davies, R. A.; Ik Soo Lim and David Duce
The development of novel molecular visualization and computational steering applications is described in this paper. Improvements to the Molecular Visualizer application, jointly developed between the schools of Chemistry and Informatics are firstly described. The effectiveness of an alternative approach utilising Perl scripting capabilities within the recent commercial release of Materials Studio 4.1 (Accelrys Plc.) will be demonstrated using specific examples. The development of simple, novel, proof-of-concept computational steering applications are also described.
The Dynamic Animation of Ambulatory Arthropods
(The Eurographics Association, 2007) Cenydd, Llyr ap; Teahan, William; Ik Soo Lim and David Duce
Whilst advances in real-time computer graphics continue to permit the development of increasingly vivid virtual worlds, the degree of interaction between the environment and the animated characters within remains relatively limited. There has been little research into the realistic real-time simulation of creatures with the ability to scale arbitrary surfaces and fully explore their environment. Natural looking animations of such feats would greatly enhance immersion in computer games, as well as being of benefit to fields such as phobia therapy and Artificial Life research. We present a system for dynamically animating ground based arthropods in real-time, capable of traversing realistically across a complex, arbitrary environment. The physical simulation of the virtual world further grounds the creatures, enabling complex emergent animations to form.
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.
Stability Analysis of Filtered Mass-Spring Systems
(The Eurographics Association, 2007) Ahmad, Alexandre; Adly, Samir; Terraz, Olivier; Ghazanfarpour, Djamchid; Ik Soo Lim and David Duce
Mass-spring systems simulations rely on the numerical integration method used for solving the resulting ordinary differential equations. Implicit schemes, which solve such equations, are unconditionally stable and are thus widely used. Part of this stability is due to force filtering which is inherent to the implicit formulation and is referred to artificial damping. We extract this artificial damping and we analyse frequencies. This analysis enables us to define a non arbitrary damping value and a stability criterion in accordance to filtering. This directly comes from a decrease of velocity vectors eigenvalues resulting in an increase of the time step in the same proportion. Moreover we applied a simple filtering model reproducing artificial damping to explicit schemes and results reveal an increase of the time step. Implementation of this method is straightforward for existing physically based simulators. Applications to cloth and fish animations are presented.
Speeding Up Isosurfacing: The Matryoshka Algorithm
(The Eurographics Association, 2007) Lopes, Sergio; Lopes, Adriano; Santos, M. Prospero dos; Ik Soo Lim and David Duce
We propose a hybrid algorithm for isosurface visualization that embraces both polygon rendering and direct surface rendering concepts. It uses raytracing to achieve high image quality but avoids the associated empty ray traversal. At the heart of the algorithm is a caching strategy resembling the famous Russian stacking dolls, that allows the processing of cells of interest from any viewing orientation. We use an optimised interval tree to extract these cells from the volume. In that respect, we propose two versions, combining grouping of cells and ordering. In comparison to the classic version of the interval tree, the memory overhead decreases but the increasing in the query time is marginal.
Advantages of allowing Hexagonal Pixels to be used as a Boundary Description Format
(The Eurographics Association, 2007) Turner, Martin J.; Ik Soo Lim and David Duce
This paper considers some algorithmic extensions and some specific advantages when using a hexagonal pixel array as compared with the usual practice of using a rectangular or square pixel raster array. Discussed are some of the algorithmic changes that are required when using pixels arranged within a hexagonal matrix. The use of a boundary hexagonal description format is considered from the point of view of; hexagonal six-connected contour edge encoding as compared with square four-connected and eight-connected descriptors, efficient probability autocorrelation analysis, direct image manipulation and algorithmic simplification. Hardware and software conversion techniques for hexagonal pixels are now being seriously considered especially with the potential emergence of hexagonal CCD censor arrangements for cameras; for example this includes a recent patent with Fuji Photo Film Co.Ltd. (US patent number 6882364 Apr 19 2005) incorporating a bidirectional honeycomb pattern.
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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