EG UK Theory and Practice of Computer Graphics 2005

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https://diglib.eg.org/handle/10.2312/900

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Arachnid Simulation: Scaling Arbitrary Surfaces
(The Eurographics Association, 2005) Cenydd, L. ap; Teahan, W.; Louise M. Lever and Mary McDerby
There has been little research done into the realistic simulation of creatures with the ability to crawl across arbitrary surfaces, clamber up walls and walk across ceilings. Realistic simulation of such feats would be of benefit to fields such as arthropod phobia therapy, the animation of computer game characters and Artificial Life research. We have implemented a system that can produce real-time simulation of a spider traversing across an arbitrary surface. The simulation uses a combination of a behavioral system, an orientation system, a procedural gait generator and an inverse kinematics solver to produce the real-time dynamic animation.
Augmented Reality Scenarios for Guitar Learning
(The Eurographics Association, 2005) Liarokapis, F.; Louise M. Lever and Mary McDerby
In this paper, an experimental self-teaching system capable of superimposing audio-visual information to support the process of learning to play the guitar is proposed. Different learning scenarios have been carefully designed according to diverse levels of experience and understanding and are presented in a simple way. Learners can select between representative numbers of scenarios and physically interact with the audio-visual information in a natural way. Audio-visual information can be placed anywhere on a physical space and multiple sound sources can be mixed to experiment with compositions and compilations. To assess the effectiveness of the system some initial evaluation is conducted. Finally conclusions and future work of the system are summarized.
Click and Brush: A Novel Way of Finding Correlations and Relationships in Visualizations
(The Eurographics Association, 2005) Wright, Michael A. E.; Roberts, Jonathan C.; Louise M. Lever and Mary McDerby
Brushing is a commonly used interaction technique that allows users to select items or an area of the visualization as the user moves the mouse. Brushing is often used with multiple views, where any co-related information is simultaneously highlighted in these linked views. Brushing is a direct manipulation technique where interaction is performed directly with the visualization. Similar effects can be engendered through indirect manipulation, using dynamic query sliders. In fact, such indirect manipulation can be more effective as the user is able to both highlight and constrain interesting features. In this paper we present a new brushing technique, called Click and Brush , that allows the user to both highlight correlations and constrain intersections in the data using direct manipulation. Users are able to highlight data (brush), fix this subset (click) and explore further intersections (subsets) of this data through further brushing operations.
Cost Prediction Maps for Global Illumination
(The Eurographics Association, 2005) Gillibrand, Richard; Debattista, Kurt; Chalmers, Alan; Louise M. Lever and Mary McDerby
There is a growing demand from the media industry, including computer games, virtual reality and simulation, for increasing realism in real-time for their computer generated images. Despite considerable advances in processing power and graphics hardware, increasing scene complexity means that it is still not possible to achieve high fidelity computer graphics in a reasonable, let alone real, time on a single computer. Cost prediction is a technique which acquires knowledge of computational complexity within the rendering pipeline as the computation progresses and then uses this to best allocate the available resources to achieve the highest perceptual quality of an image in a time constrained system. In this paper we describe a method of acquiring computational cost complexity knowledge within a high fidelity graphics environment. This cost map may be used in combination with other perceptually derived maps to control a selective renderer in order to achieve the best perceptual quality results for a user specified frame-rate.
The Data Surface Interaction Paradigm
(The Eurographics Association, 2005) Lindell, Rikard; Larsson, Thomas; Louise M. Lever and Mary McDerby
This paper presents, in contrasts to the desktop metaphor, a content centric data surface interaction paradigm for graphical user interfaces applied to music creativity improvisation. Issues taken into account were navigation and retrieval of information, collaboration, and creative open-ended tasks. In this system there are no windows, icons, menus, files or applications. Content is presented on an infinitely large two-dimensional surface navigated by incremental search, zoom, and pan. Commands are typed aided by contextual help, visual feedback, and text completion. Components provide services related to different content modalities. Synchronisation of data surface content sustains mutual awareness of actions and mutual modifiability. The prototype music tool was evaluated with 10 users; it supported services expected by users, their creativity in action, and awareness in collaboration. User responses to the prototype tool were: It feels free, it feels good for creativity, and it s easy and fun to use.
An Efficient Caching Technique for Rendering Translucent Materials
(The Eurographics Association, 2005) Keng, Shih-Ling; Lee, Wang-Yeh; Chuang, Jung-Hong; Louise M. Lever and Mary McDerby
This paper presents an efficient rendering technique for translucent materials using caches. The proposed caching scheme, inspired by the irradiance caching method, is integrated into a hierarchical rendering technique for translucent materials. We propose a split-disk model to determine the cache distribution and derive the subsurface illuminance gradient used for interpolation by reformulating the equation of dipole diffusion approximation as a 3D convolution process. Our experiments show that only a few caches are required to interpolate the entire image, while the visual difference is negligible. The speedup could be achieved up to one order of magnitude.
Fast Simulation of Facial Tissue Deformations Using Mass-Spring Chain Algorithm
(The Eurographics Association, 2005) Duysak, A.; Zhang, J. J.; Louise M. Lever and Mary McDerby
We propose a method to develop a unique head model to be used in craniofacial surgery simulations. This method considers the shape of the head and skull structure and provides a polygonal model, which includes different tissue layers with realistic tissue thickness. We also introduce the use of the new deformation simulation technique called mass-spring chain algorithm in simulation of facial tissue deformations caused by operations on the bone structure. This method produces plausible results and considerably reduces the simulation time.
Freehand 3D Curve Recognition and Oversketching
(The Eurographics Association, 2005) Han, Li; Amicis, Raffaele De; Conti, Giuseppe; Louise M. Lever and Mary McDerby
In the CAD/CAS field, the increasing domination of spline-based graphic objects has driven a great attention to methods focusing on the management of free-form curves. Based on the quick brainstorm illustration and stepwise refinement characteristics in conceptual designing stage, we present a method, which automatically reconstructs the designer s free-form 3D curve through recognizing his design intention . This algorithm automatically extracts the relevant control points through corner detection and dynamic-threshold sampling mechanism; as a result the Bspline curve is approximately produced. Furthermore, considering the ambiguity of designer s intention during the conceptual designing, this redraw operation feature is implemented through the so-called over-sketching . For this we introduce constrained length and tangent angle features, which supports fully free form 3D curve sketching, and it is capable of effectively smoothen transition interval. The method has been tested with various types of sketches, which are rendered in 3D scene environment. We further discuss the modification and its application to surfaces.
Implementing an Improved Stereoscopic Camera Model
(The Eurographics Association, 2005) Froner, Barbara; Holliman, Nick; Louise M. Lever and Mary McDerby
The usable perceived depth range of all stereoscopic 3D displays is limited by human factors considerations to a bounded range around the plane of the display. To account for this our Three Region stereoscopic camera model is able to control the depth mapping from scene to display while allowing a defined region of interest in scene depth to have an improved perceived depth representation compared to other regions of the scene. This can be categorized as a focus+context algorithm that manipulates stereoscopic depth representation along the viewing axis of the camera. We present a new implementation of the Three Region stereoscopic camera model as a Utility plug-in for the popular modelling and rendering package 3ds max. We describe our user interface, designed to incorporate stereoscopic image generation into the user s natural work flow. The implementation required us to overcome a number of technical challenges including; accurately measuring scene depth range, simulating asymmetric camera frustum in a system only supporting symmetric frustum, merging multiple renderings and managing anti-aliasing in layered images. We conclude from our implementation that it is possible to incorporate high quality stereoscopic camera models into standard graphics packages.
Implementing FastMap on the GPU: Considerations on General-Purpose Computation on Graphics Hardware
(The Eurographics Association, 2005) Reina, G.; Ertl, Thomas; Louise M. Lever and Mary McDerby
In this paper we focus on the implications of implementing generic algorithms on graphics hardware. As an example, we ported the dimensionality reduction algorithm FastMap to fragment programs and thus accelerated it by orders of magnitude, allowing for interactive tweaking and evaluating of the algorithm parameters for datasets of several hundred thousand points and tens of dimensions; even the animation of structural changes in relation to parameters is possible. This allows to complement the algorithmic heuristic used by FastMap by explorative results from human interaction. Such an approach can be considered a heuristic in itself, but has the advantage of being based on visual feedback, therefore allowing for iterative improvement of the results. Thus we demonstrate how to benefit from the high execution parallelism on commodity graphics hardware as an alternative to making use of other, more costly, multiprocessing techniques. We discuss performance and bandwidth aspects as well as accuracy problems since these results are of more general interest and can be applied to general processing on graphics hardware as a whole.
Integrating Abstract and Physical Molecular Model Interaction
(The Eurographics Association, 2005) Thorne, Dave; Pettifer, Steve; Attwood, Terri; Louise M. Lever and Mary McDerby
Historically, bioinformaticians have carried out protein analysis in one of two ways: by concentrating on either the physical structural representation of the subject data or a more abstract sequential representation. This paper describes a system currently in development at The University of Manchester that attempts to unify these two paradigms. We discuss the use of high-end rendering techniques to greatly increase the level of detail and interactivity of molecular visualisation, and describe the requirements placed upon that visualisation by the relationship between the abstract and physical models.
Keyframing Particles of Physically Based Systems
(The Eurographics Association, 2005) Dingle, Brent M.; Keyser, John; Louise M. Lever and Mary McDerby
This paper will present a way to use keyframing methods for particle motion to enhance the visual effects and user controllability of physically based particle systems. This will be done using an adaptive correction methodology. This will allow for three general types of keyframing: position to position, density to density, and boundary to boundary. While similar techniques have been explored in flocking behaviors and robotic motion planning, this paper implements them in conjunction with physically based systems and allows a comparison of particle based keyframing to keyframing achieved using other methodologies. To illustrate the technique we will present two examples. The first morphs between two particle images. The second forces a smoke-like substance to change into various letters of the alphabet. While these are specific examples the techniques presented herein should apply to most any particle based system to achieve a diverse range of effects.
Perceptual Level of Detail for Efficient Ray Tracing of Complex Scenes
(The Eurographics Association, 2005) Yang, X.; Chalmers, A.; Louise M. Lever and Mary McDerby
Rendering complex scenes in real time remains one of the major challenges in computer graphics. Recent research in perceptual rendering algorithms and level of detail techniques have shown that, by exploiting knowledge of the human visual system, significant computation time can be saved by only rendering in high quality those parts of the image that the user will see. This paper describes how a level of detail approach can be used to reduce overall computation time when users are undertaking a task within a virtual environment.
Perceptually-Oriented Interest Management In Large-Scale Networked Virtual Environments
(The Eurographics Association, 2005) Dunwell, I.; Whelan, J. C.; Louise M. Lever and Mary McDerby
Amongst the most significant challenges in developing large-scale multi-user virtual environments is the efficient filtering of data to each user - a process commonly described as "interest management". This work-in-progress paper presents a broad summary of existing approaches, placing an emphasis upon the relationship between interest management and human perception. Subsequently, an introduction to the challenges in evaluating the success of interest management, given such a relationship to perception, is presented. The initial development of a test environment aimed at overcoming some of the challenges in providing a platform for such evaluation is then described, together with discussion of a perceptually-oriented approach to interest management which relies on the description of perception as a dynamic field, formed by analysis of the user's focus.
Perlin Noise and 2D Second-Order Tensor Field Visualization
(The Eurographics Association, 2005) Liu, J.; Perrin, J.; Turner, M.; Hewitt, W. T.; Louise M. Lever and Mary McDerby
There has been much research in the use of texture for visulization the vector field data, whereas there has only been a few papers concerned specifically with tensor field data. This set is more complex and embeds more information than vector fields. In this paper, firstly texture is modeled by Perlin Noise. We show that by controlling the parameters of Perlin Noise, the user can control the output texture effectively, which is similar to Spot Noise. Then the modeled texture is used to visualize eigenvector fields of tensor fields by simple convolution. Several examples are shown. Compared to Line Integration Convolution, this method does not need to integrate the streamline along the vector field.
A Psychologically-Based Simulation of Human Behaviour
(The Eurographics Association, 2005) Rymill, Stephen J.; Dodgson, Neil A.; Louise M. Lever and Mary McDerby
We describe a system designed to simulate human behaviour in crowds in real-time, concentrating particularly on collision avoidance. The algorithms used are based heavily on psychology research, and the ways this has been used are explained in detail. We argue that this approach gives better results than conventional methods, and detail further work to be done.
Real-Time Animation of Particles and Seaweeds in Underwater Scenes
(The Eurographics Association, 2005) Coulais, Y.; Ghazanfarpour, D.; Terraz, O.; Thon, S.; Louise M. Lever and Mary McDerby
Water is one of the most important natural phenomena to be rendered in computer graphics. Although ocean waves animation has been well studied in Computer graphics, only few studies have been done for underwater animation. In this paper, we present a new real-time method for animation of suspended particles and seaweeds in underwater scenes. One of the main advantages of this method, compared to other approaches, is the real-time animation of submerged objects by taking into account some natural underwater forces that govern their movements, such as forces generated by water surface in deep and shallow waters as well as underwater currents. Taking into account forces generated by ocean surface is an original approach in Computer Graphics. In addition, real-time animation of complex underwater scenes composed of a great number of particles and seaweeds can be performed by the use of appropriate levels of details.
Real-time Simulation of Crowds Using Voronoi Diagrams
(The Eurographics Association, 2005) Champagne, J.; Tang, W.; Louise M. Lever and Mary McDerby
In this paper, we present a novel approach for real-time simulation of crowds. Our method is to compute generalised 2D Voronoi diagrams on environment maps for the locations of agents in the crowds. The Voronoi diagrams are generated efficiently with graphics hardware by calculating the closest Voronoi site and the distance to that site using polygon scan conversion and the z-buffer depth comparison. Because Voronoi diagrams have unique features of spatial tessellations which give optimised partitions of space for locating the agents especially groups of agents in a virtual environment, agents in the same group are placed within the Voronoi region which encloses the nearest locations to the geometric centre of the group. Each group of agents within its own Voronoi region follows the geometric centre of the region that is moving on the paths of the maps. During the simulation, agents in groups move closely together and avoid collusions with other groups on the way. With carefully designed rules for collision response the algorithm can generate natural-looking group behaviors of large crowds in real-time. Each agent within a group only detects collisions with other agents of the group and with static obstacles in the environment. Efficiency of the simulation is also gained through such multi-level behavioral simulation approach.
Selective Parallel Rendering for High-Fidelity Graphics
(The Eurographics Association, 2005) Debattista, K.; Sundstedt, V.; Pereira, F.; Chalmers, A.; Louise M. Lever and Mary McDerby
High-Fidelity rendering of complex scenes is one of the primary goals of computer graphics. Unfortunately, high- fidelity rendering is notoriously computationally expensive. In this paper we present a framework for high-fidelity rendering in reasonable time through our Rendering on Demand system. We bring together two of the main acceleration methods for rendering: selective rendering and parallel rendering. We present a selective rendering system which incorporates selective guidance. Amongst other things, the selective guidance system takes advantage of limitations in the human visual system to concentrate rendering efforts on the most perceptually important features in an image. Parallel rendering helps reduce the costs further by distributing the workload amongst a number of computational nodes. We present an implementation of our framework as an extension of the lighting simulation system Radiance, adding a selective guidance system that can exploit visual perception. Furthermore, we parallelise Radiance and its primary acceleration data structure, the irradiance cache, and also use the selective guidance to improve load balancing of the distributed workload. Our results demonstrate the effectiveness of the implementation and thus the potential of the rendering framework.
Simulating the Cumulative Effects of Multiple Impacts using 'Fracture Maps'
(The Eurographics Association, 2005) Clifton, T.; Louise M. Lever and Mary McDerby
Abstract Much research has been carried out within the computer graphics community to simulate the effects of collisions between deformable and rigid bodies, but little has been proposed to take into account the effects of one collision, on later impacts. We present a novel approach to model and retain information regarding specific impacts that can be used to better approximate the results of future collisions, taking into account non-visible effects caused as objects collide within a scene. We propose the notion of fracture maps to store and evaluate stress and strain factors for polygonal meshes in order to accommodate the cumulative effects of impacts, even if these effects are not immediately visible to the human eye. We describe the initial work carried out towards this research, including the methodology to create and update these impacts and how they can be used to determine both deformation and decimation of meshes from multiple impacts. We discuss requirements for completing the research, and future directions we would extend the concept further.

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