2010 - EG UK Theory and Practice of Computer Graphics

Permanent URI for this collection

https://diglib.eg.org/handle/10.2312/905

Browse

Now showing 1 - 20 of 35

Anatomically Plausible Surface Alignment and Reconstruction
(The Eurographics Association, 2010) Paulsen, Rasmus R.; Larsen, Rasmus; John Collomosse and Ian Grimstead
With the increasing clinical use of 3D surface scanners, there is a need for accurate and reliable algorithms that can produce anatomically plausible surfaces. In this paper, a combined method for surface alignment and reconstruction is proposed. It is based on an implicit surface representation combined with a Markov Random Field regularisation method. Conceptually, the method maintains an implicit ideal description of the sought surface. This implicit surface is iteratively updated by realigning the input point sets and Markov Random Field regularisation. The regularisation is based on a prior energy that has earlier proved to be particularly well suited for human surface scans. The method has been tested on full cranial scans of ten test subjects and on several scans of the outer human ear.
The Effect of Discretised and Fully Converged Spatialised Sound on Directional Attention and Distraction
(The Eurographics Association, 2010) Harvey, Carlo; Walker, Steve; Bashford-Rogers, Thomas; Debattista, Kurt; Chalmers, Alan; John Collomosse and Ian Grimstead
A major challenge in Virtual Reality (VR) is to be able to provide interactive rates of realism. However this is very computationally demanding and only recently has high-fidelity rendering become close to interactive rates through a series of novel exploitations of visual perception; to render parts of the scene that are not currently being attended by the viewer at a much lower quality without the difference being perceived. This paper investigates the effect spatialised directional sounds, both discrete and converged have on the visual attention of the user with and without an auditory cue present in the scene. We verify the worth of investigating subliminal saccade shifts from directional audio impulses via a pilot study to eye track participant's free viewing a scene with an audio impulse and an acoustic identifier and also with an audio impulse and no acoustic identifier versus a control. By selecting look zones, we can identify how long users are spending attending a particular area of a scene in these scenarios. This work also investigates whether the effect prevailed, and if so to what extent, with discretised spatialised sound as opposed to a fully converged audio sample. We also present a novel technique for generating interactive discrete acoustic samples from arbitrary geometry. We show that even without an acoustic identifier in the scene, directional sound provides enough of an impulse to guide subliminal saccade shifts and affect perception in such a way that this can be used to guide selective rendering of the scenes.
Evaluation of A Viseme-Driven Talking Head
(The Eurographics Association, 2010) Dey, Priya; Maddock, Steve; Nicolson, Rod; John Collomosse and Ian Grimstead
This paper introduces a three-dimensional virtual head for use in speech tutoring applications. The system achieves audiovisual speech synthesis using viseme-driven animation and a coarticulation model, to automatically generate speech from text. The talking head was evaluated using a modified rhyme test for intelligibility. The audiovisual speech animation was found to give higher intelligibility of isolated words than acoustic speech alone.
Sketch-Based Posing of 3D Faces for Facial Animation
(The Eurographics Association, 2010) Gunnarsson, Orn; Maddock, Steve; John Collomosse and Ian Grimstead
This paper presents a novel approach to creating 3D facial animation using a sketch-based interface where the animation is generated by interpolating a sequence of sketched key poses. The user does not need any knowledge of the underlying mechanism used to create different expressions or facial poses, and no animation controls or parameters are directly manipulated. Instead, the user sketches the desired shape of a facial feature and the system reconstructs a 3D feature which fits the sketched stroke. This is achieved using a maximum likelihood framework where a statistical model in conjunction with Hidden Markov Models handles sketch detection, and a hierarchical statistical mapping approach reconstructs a posed 3D mesh from a low-dimensional representation.
Using Processing to Develop iCove: a Tool for Interactive Coastal Oceanographic Visualization
(The Eurographics Association, 2010) George, Richard L. S. F.; Roberts, Jonathan C.; Davies, Alan G.; John Collomosse and Ian Grimstead
We have been developing iCove: the interactive coastal oceanographic visualization environment. The challenge for the ocean scientists is that their models are complex and the datasets that are generated are huge. Furthermore, the oceanographers wish to interactively investigate and quantitatively compare different runs of these models. We propose a novel visual analytics tool to permit detailed exploration through interactive data querying to enable their analysis. This paper presents our experience of building iCove in Processing especially in comparison with our previous oceanographic tool building in VTK.
Real-Time Traffic Simulation Using Cellular Automata
(The Eurographics Association, 2010) Applegate, Christopher S.; Laycock, Stephen D.; Day, Andy M.; John Collomosse and Ian Grimstead
In this paper, we present a method to simulate large-scale traffic networks, at real-time frame-rates. Our novel contributions include a method to automatically generate a road graph from real-life data, and our extension to a discrete traffic model, which we use to simulate traffic, demonstrating continuous vehicle motion between discrete locations. Given Ordnance Survey data, we automatically generate a road graph, identifying roads, junctions, and their connections. We distribute cells at regular intervals throughout the graph, which are used as discrete vehicle locations in our traffic model. Vehicle positions are then interpolated between cells to obtain continuous animation. We test the performance of our model using a 500 x 500m2 area of a real city, and demonstrate that our model can simulate over 600 vehicles at real-time frame-rates (greater than 80 percent network density).
Using the Discrete Fourier Transform for Character Motion Blending and Manipulation - a Streamlined Approach
(The Eurographics Association, 2010) Molnos, Michael R. L.; Laycock, Stephen D.; Day, Andy M.; John Collomosse and Ian Grimstead
Motion capture data allows natural-looking motion to be bestowed upon simulated characters. Research has sought ways of extending the range of motions it can reproduce. One such method involves blending between captured sequences in the frequency domain. This paper streamlines the approach taken by similar previous work. Higher efficiency is obtained both by shifting computations from runtime to pre-processing and by using a simpler technique, which is also more flexible allowing the method to be used for a greater range of motions. Furthermore, the already-known use of a triangular network defining a continuous blending space is instead presented as an adjustable interface element which is both intuitive and more flexible than applied to earlier work. As before input data may be sparse yet still allows the creation of a continuous spectrum of subtly varying motions, enabling characters to integrate well in their environment. Weighting calculation, blending and Fourier synthesis of realistic-looking motion using five harmonics requires 0.39 ?s per degree of freedom for each frame in the created sequence - a one-off cost incurred only when blending ratios change. This figure can be improved further using the proposed level-of-detail adjustments, which, combined with its small memory footprint, makes the method particularly suitable for the simulation of crowds.
Anisotropic Kuwahara Filtering with Polynomial Weighting Functions
(The Eurographics Association, 2010) Kyprianidis, Jan Eric; Semmo, Amir; Kang, Henry; Döllner, Jürgen; John Collomosse and Ian Grimstead
In this work we present new weighting functions for the anisotropic Kuwahara filter. The anisotropic Kuwahara filter is an edge-preserving filter that is especially useful for creating stylized abstractions from images or videos. It is based on a generalization of the Kuwahara filter that is adapted to the local shape of features. For the smoothing process, the anisotropic Kuwahara filter uses weighting functions that use convolution in their definition. For an efficient implementation, these weighting functions are usually sampled into a texture map. By contrast, our new weighting functions do not require convolution and can be efficiently computed directly during the filtering in real-time. We show that our approach creates output of similar quality as the original anisotropic Kuwahara filter and present an evaluation scheme to compute the new weighting functions efficiently by using rotational symmetries.
An Improved Discrete Level of Detail Model Through an Incremental Representation
(The Eurographics Association, 2010) Ribelles, Jose; López, Angeles; Belmonte, Oscar; John Collomosse and Ian Grimstead
Real-time applications such as computer and video games, virtual reality and scientific simulation require rendering of complex models for realism. Graphics rendering engines include multiresolution modelling techniques to accelerate the visualization process. The Discrete Level of Detail framework (DLoD) is usually the most popular while the Continuous Level of Detail framework (CLoD) is still not as widely used by software developers. In this paper, we first discuss the benefits and drawbacks of both frameworks. Then, we present a model based on coding a discrete number of levels of detail (LoDs), with more LoDs coded than is usual in DLoD, and with an incremental representation, which is often used in CLoD. This model obtains a performance similar to DLoD by providing optimized LoDs for efficient visualization, while the popping effect is imperceptible. We present specific proposals for each of the three main stages involved in multiresolution processing: geometry simplification, construction of the incremental representation and retrieval of either uniform or view-dependent LoDs.
3D Modelling of Complex Biological Structures: The Oviduct
(The Eurographics Association, 2010) Burkitt, Mark; Romano, Daniela M.; Walker, Dawn C.; Fazeli, Alireza; John Collomosse and Ian Grimstead
A novel technique using a particle system constrained by Newtonian forces is presented for the algorithmic construction of small scale, complex 3D biological structures based on real world biological data. This allows models of structures too small to be accurately recreated using medical imaging technologies such as Magnetic Resonance Imaging (MRI) to be created. The resulting model provides a geometrically realistic 3D environment which can be used to study the biological interactions which occur within. The technique is used to create a model of an oviduct, but could also be applied to similar organs such as the colon. The model is validated using measurements and visual comparisons from biological data. Finally, the technique is implemented using single-core and multi-core CPU techniques and using GPU acceleration. The performance of each implementation is then compared.
Approximating Poisson Disk Distributions by Means of a Stochastic Dither Array
(The Eurographics Association, 2010) Alford, Jennifer R.; Sheppard, David G.; John Collomosse and Ian Grimstead
Achieving blue noise point set distributions has been a common goal of two largely separate research communities: computer graphics and digital halftoning. Computer graphics research has focused largely on geometric solutions in continuous spaces. Digital halftoning research has focused on signal processing solutions in discrete imagebased space. Usage of Poisson Disk point sets in computer graphics has grown beyond sampling, including object distribution and texturing, among others. The image-based field of digital halftoning can provide additional tools for graphics researchers and practitioners. It is of interest to explore the suitability of digital halftoning technology to two classic problems in computer graphics: (1) approximating Poisson Disk point distributions of constant density and (2) importance sampling of an underlying importance function. Exemplary methods from each field are implemented and, by applying well-established measures of the radially averaged power spectrum and anisotropy plots, are shown to be quite similar, although the approaches are mathematically not equivalent. Additionally, we compare the relative radius of the point sets. Further, the ability of dither array construction techniques to shape spectral characteristics of dot patterns is shown with several variations of design parameters.
Implicit Surface Reconstruction and Feature Detection with a Learning Algorithm
(The Eurographics Association, 2010) Kaye, Patrizia; Ivrissimtzis, Ionnis; John Collomosse and Ian Grimstead
We propose a new algorithm for implicit surface reconstruction and feature detection. The algorithm is based on a self organising map with the connectivity of a regular 3D grid that can be trained into an implicit representation of surface data. The implemented self organising map stores not only its current state but also its recent training history which can be used for feature detection. Preliminary results show that the proposed algorithm gives good quality reconstructions and can detect various types of feature.
Computer Modelling of Theatrical Sets
(The Eurographics Association, 2010) Stephenson, Ian; Pride, Rebecca; John Collomosse and Ian Grimstead
Here we discuss the design and implementation of a modelling tool specifically targeted for use by designers of theatrical sets. By applying domain specific knowledge and contraints to the design of the software, we demonstrate a system which can be used without signifigant training, by users with no previous computer graphics experience. We present initial end user experiences of using the tool in designing a real production of The First Arabian Night .
Surfel Based Geometry Reconstruction
(The Eurographics Association, 2010) Andersen, Vedrana; Aanæs, Henrik; Bærentzen, Jacob Andreas; John Collomosse and Ian Grimstead
We propose a method for retrieving a piecewise smooth surface from noisy data. In data acquired by a scanning process sampled points are almost never on the discontinuities making reconstruction of surfaces with sharp features difficult. Our method is based on a Markov Random Field (MRF) formulation of a surface prior, with the surface represented as a collection of small planar patches, the surfels, associated with each data point. The main advantage of using surfels is that we avoid treating data points as vertices. MRF formulation of the surface prior allows us to separately model the likelihood (related to the mesh formation process) and the local surface properties. We chose to model the smoothness by considering two terms: the parallelism between neighboring surfels, and their overlap. We have demonstrated the feasibility of this approach on both synthetical and scanned data. In both cases sharp features were precisely located and planar regions smoothed.
Interval Based Data Structure Optimization
(The Eurographics Association, 2010) Duffy, Brian; Carr, Hamish; John Collomosse and Ian Grimstead
Isosurface extraction is a widely exploited visualization technique for volumetric data on all manner of grid representation. The basic technique is often used to explore and measure many properties of data sets of ever increasing size. Therefore, data structures and algorithms that facilitate interactive exploration and fast processing of isosurfaces of large data sets is of paramount importance. While many optimal methods have been proposed to accelerate isosurface extraction, many of these algorithms have limitations with regards to storage costs and data quantization. In some cases these limitations preclude their practical application. We present a very simple clustering and volume compression technique based on observations in the span space and show that applying this technique to existing methods can reduce their storage cost. We show results for real data validating our technique.
From Tabular Data to Metaphoric Landscape Visualisation - A Template-based Approach
(The Eurographics Association, 2010) Mohamed, Farhan; Chen, Min; Grant, Phil W.; John Collomosse and Ian Grimstead
This paper presents a template-based approach to the generation of metaphoric visualisation from tabular data. This technique allows a coherent transformation between a relatively abstract visual representation (e.g., a treemap) to a more expressive metaphor (e.g., a virtual atlas). It enables easy customisation of existing metaphors by ordinary users and uncomplicated introduction of new metaphors by expert users. It provides automation in much of the pipeline for creating a metaphoric visualisation, except aspects where crucial semantic input is necessary. The technique was realised in a software system, vis4me2. As a case study, the outcome of the latest UK Research Assessment Exercise (RAE2008) was used to demonstrate the usability and effectiveness of this technique.
Remote Scientific Visualization for Large Datasets
(The Eurographics Association, 2010) Turner, Martin; Leaver, George; Perrin, James; John Collomosse and Ian Grimstead
Remote scientific visualization, where rendering services are provided by larger scale systems than are available on the desktop, are becoming increasingly important as dataset sizes increase beyond the capabilities of desktop workstations. Uptake of such services relies on access to suitable visualization applications and the ability to view the resulting visualization in a convenient form. We apply five rules from the e-Science community to meet these goals with the porting of a commercial visualization package to a large scale system and the integration of this code with the Access Grid. Example use cases from Materials Science are considered.
Multiresolution Modeling Using Fractal Image Compression Techniques
(The Eurographics Association, 2010) Belmonte, Óscar; Sancho, Sergio; Ribelles, José; John Collomosse and Ian Grimstead
This work presents a new approach to the multiresolution modeling of polygonal meshes. This approach is based on the theoretically well-established fractal image compression techniques. A polygonal mesh is represented as a fractal using an iterated function system (IFS). In this way, a level of detail can be obtained over a region of the mesh by successively iterating the IFS. The main advantage is that it becomes possible to recover new levels of detail that were not present in the original mesh, so that the quality is not lost as the observer approaches the mesh. Another characteristic is that the same representation can be used over textures, and in this case the algorithm is directly implemented over the GPU. The visualization time obtained allows this new approach to be used in real-time interactive computer graphic applications.
Virtual Femoral Palpation Simulation for Interventional Radiology Training
(The Eurographics Association, 2010) Coles, Timothy R.; Gould, Derek A.; John, Nigel W.; Caldwell, Darwin G.; John Collomosse and Ian Grimstead
A femoral palpation simulation for training purposes has been developed to simulate the initial steps of the Seldinger technique which is currently neglected in both commercial and academic medical training simulations. The simulation co-locates visual and haptic feedback through the use of an augmented reality video see-through visualisation whilst requiring no headwear to be worn. The visual simulation implements shadowing of the users real hand in the virtual world to increase depth perception, textured deformable tissue and visually realistic cloth, whilst haptic feedback combines both tactile and force feedback based on in-vivo measured force and tactile data. The simulation is a work in progress and is to undergo validation.
Audio-Visual Animation of Urban Space
(The Eurographics Association, 2010) Richmond, Paul; Smyrnova, Yuliya; Maddock, Steve; Kang, Jian; John Collomosse and Ian Grimstead
We present a technique for simulating accurate physically modelled acoustics within an outdoor urban environment and a tool that presents the acoustics alongside a visually rendered counterpart. Acoustic modelling is achieved by using a mixture of simulating ray-traced specular sound wave reflections and applying radiosity to simulate diffuse reflections. Sound rendering is applied to the energy response of the acoustic modelling stage and is used to produce a number of binaural samples for playback with headphones. The visual tool which has been created unites the acoustic renderings with an accurate 3D representation of the virtual environment. As part of this tool an interpolation technique has been implemented allowing a user controlled walkthrough of the simulated environment. This produces better sound localisation effects than listening from a set number of static locations.

Browse

Browsing 2010 - EG UK Theory and Practice of Computer Graphics by Issue Date

Results Per Page

Sort Options