EG UK Theory and Practice of Computer Graphics 2007

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https://diglib7.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.
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.
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.
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.
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.
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.
Data Driven Graphical Applications: A Fluid Approach
(The Eurographics Association, 2007) Jones, A.; Mantle, C.; Cornford, D.; Ik Soo Lim and David Duce
The inclusion of high-level scripting functionality in state-of-the-art rendering APIs indicates a movement toward data-driven methodologies for structuring next generation rendering pipelines. A similar theme can be seen in the use of composition languages to deploy component software using selection and configuration of collaborating component implementations. In this paper we introduce the Fluid framework, which places particular emphasis on the use of high-level data manipulations in order to develop component based software that is flexible, extensible, and expressive. We introduce a data-driven, object oriented programming methodology to component based software development, and demonstrate how a rendering system with a similar focus on abstract manipulations can be incorporated, in order to develop a visualization application for geospatial data. In particular we describe a novel SAS script integration layer that provides access to vertex and fragment programs, producing a very controllable, responsive rendering system. The proposed system is very similar to developments speculatively planned for DirectX 10, but uses open standards and has cross platform applicability.
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.
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.
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 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).
GPU-Based Wind Animation of Trees
(The Eurographics Association, 2007) Skjermo, Jo; Ik Soo Lim and David Duce
This paper present a simplified approach to wind animation of natural looking tree stems and branches. The presented approach is composed from several earlier works by a number of authors, each adapted to increase its suitability for processing on a Graphic Processing Unit (GPU). The outlined approach uses two passes through the GPU. The first pass samples from a simple wind force simulator based on sine sums. It then animates the parameters and the control points defining each branch using the sampled force, taking advantage of the parallel nature of GPU s. The second pass uses a previously presented GPU-based deformer to generate and render actual models of each branch, using the animated control points.
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.
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
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.
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.
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.
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.
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.
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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