EG UK Theory and Practice of Computer Graphics 2010

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

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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.
Efficient Image Blur in Web-Based Applications
(The Eurographics Association, 2010) Kraus, Martin; John Collomosse and Ian Grimstead
Scripting languages require the use of high-level library functions to implement efficient image processing; thus, real-time image blur in web-based applications is a challenging task unless specific library functions are available for this purpose. We present a pyramid blur algorithm, which can be implemented using a subimage copy function, and evaluate its performance with various web browsers in comparison to an infinite impulse response filter. While this pyramid algorithm was first proposed for GPU-based image processing, its applicability to web-based applications indicates that some GPU techniques are of more general interest than previously assumed.
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.
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.
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.
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.
Perception of Clones in Forest Rendering
(The Eurographics Association, 2010) Purvis, Alan; Sundstedt, Veronica; John Collomosse and Ian Grimstead
The application of instanced clones represents a powerful technique for reducing the time and space requirements of the storage and visualization of large populations of similar objects. This paper presents the results of several perceptual experiments into the application of cloning to plant populations, within the context of a project to explore the use of resource-acquisition based techniques to model plant distributions. The perceptive effects of clone rotation on human subjects will be explored, with the goal of stratifying clone rotations and minimizing their detection. The perceptual effects of clone number, plant species heterogeneity and appearance will also be explored.
Integrating Haptic Interaction Into An Existing Virtual Environment Toolkit
(The Eurographics Association, 2010) Scopes, Peter; Smith, Shamus P.; John Collomosse and Ian Grimstead
There is increasing demand for haptic, or touch-based, interaction in virtual environments. Although many haptic devices come with APIs to enable the development of haptic-based applications, many do not provide the same level of graphical support available in virtual environment or game technology toolkits. This paper will discuss the integration of haptic interaction into an existing virtual environment toolkit. By creating a flexible middleware component, haptic interaction and force feedback for a haptic device can augment sensory experiences in existing virtual environments. A user study was conducted to evaluate the integration of haptics and realistic physics in an example virtual environment.
Animating Horse Gaits and Transitions
(The Eurographics Association, 2010) Murphy, James E.; Carr, Hamish; O'Neill, Michael; John Collomosse and Ian Grimstead
Animations of horses are commonly used for entertainment purposes. A realistic animated model must move with a gait appropriate to its velocity. We present a kinematic animation system in which a horse model moves using gaits and transitions based on predictions from Dynamic Similarity theory. A Genetic Programming technique is used to evolve gait motion with dynamically adjustable limb extent. The system is controlled in real-time using a MIDI controller system based around the model's Froude number. We were successful in producing high quality animations of the horse's natural gaits and transitions.
A Thin-plate CAD Mesh Model Splitting Approach Based on Fitting Primitives
(The Eurographics Association, 2010) Geng, Chun; Suzuki, Hiromasa; Yan, Dong-Ming; Michikawa, Takasi; Sato, Yuichi; Hashima, Masayoshi; Ohta, Eiji; John Collomosse and Ian Grimstead
Extracting structural information from mesh models is crucial for Simulation Driven Design (SDD) in industrial applications. Focusing on thin-plate CAD mesh models (the most commonly used parts in electronic products such as PCs, mobile phones and so on), we present an algorithm based on primitive fitting for segmenting thin-plate CAD mesh models into parts of three different types, two of which are extruding surfaces and the other is a lateral surface. This method can be used for solid model reconstruction in the SDD process. Our approach involves two steps. First, a completely automatic method for accurate primitive fitting on CAD meshes is proposed based on the hierarchical primitive fitting framework. In the second step, a novel procedure is proposed for splitting thin-plate CAD mesh models by detecting parallel extruding surfaces and lateral surfaces. The method presented here has been proved to work smoothly in applications of real product design.
A Multi-Windows Approach for Sketch-Based Conceptual Design System
(The Eurographics Association, 2010) Gharib, Islam; Qin, Shengfeng; John Collomosse and Ian Grimstead
Sketching plays a very important role in conceptual design. In this early stage of the design process, designers have developed some ways to help them to explore designs. Sketching is one of these methods. In this paper, a study of sketch nature was carried and a proposed sketch-based interface for modeling was designed. The sketch nature study investigated the cognitive activities in sketching process, analyzed sketches of design students and professional designers, and collected data about sketching process and sketch-based systems requirements from designers to develop sketching scenarios and determine sketch-based systems requirements. These requirements were used to design a proposed sketch-based system for conceptual design with a multi-windows approach. The proposed system aims to provide an easy way for designers to sketch freely and for ideas to flow easily by using a multi-windows approach for sketching, 3D generation and rendering.
Craniofacial Reconstruction Based on Skull-face Models Extracted from MRI Datasets
(The Eurographics Association, 2010) Salas, Miguel; Maddock, Steve; John Collomosse and Ian Grimstead
We present a method for extracting skull and face models from MRI datasets and show how the resulting dataset is used in a craniofacial reconstruction (CFR) system. Datasets for 60 individuals are used to produce a database of 3D skull-face models, which are then used to give faces to unknown skulls. In addition to the skull-face geometry, other information about the individuals is known and can be used to aid the reconstruction process. The results of the system were evaluated using different criteria providing the system with different combinations of age, gender, body build and geometric skull features. Based on a surface to surface distance metric, the real and estimated faces produced were compared using different head models from the database with a leave-one-out strategy. The reconstruction scores obtained with our CFR system were comparable in magnitude (average distance less than 2.0 mm) to other craniofacial reconstruction systems. The results suggest that it is possible to obtain acceptable face estimations in a CFR system based on skull-face information derived from MRI data.
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.
Rendering Large Point Datasets with GPU Shaders
(The Eurographics Association, 2010) Aguirre, Hugo; Gutierrez, Diego; Perrin, James S.; John Collomosse and Ian Grimstead
This paper demonstrates how programmable GPUs are a powerful tool to display large point datasets at an interactive frame rate. Point datasets are commonly used to analyse and solve complex problems, but rendering them is always an expensive task in computational terms. This paper researches the possibilities that GPUs and shading languages offer for rendering large datasets on modest computers and the improvements in speed and quality. GPU techniques to represent scalar and vector glyph are also described. The GPU method is compared with common methods, such as using polygons or textures. The shader glyphs are drawn onto planar primitives using equations to generate surface, lighting and depth information. The improved computational efficiency allows the display of larger datasets with a simultaneous increase in visual quality.
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).
Agent-based Large Scale Simulation of Pedestrians With Adaptive Realistic Navigation Vector Fields
(The Eurographics Association, 2010) Karmakham, Twin; Richmond, Paul; Romano, Daniela M.; John Collomosse and Ian Grimstead
A large scale pedestrian simulation method, implemented with an agent based modelling paradigm, is presented within this paper. It allows rapid prototyping and real-time modifications, suitable for quick generation and testing of the viability of pedestrian movement in urban environments. The techniques described for pedestrian simulation make use of parallel processing through graphics card hardware allowing simulation scales to far exceed those of serial frameworks for agent based modelling. The simulation has been evaluated through benchmarking of the performances manipulating population size, navigation grid, and averaged simulation steps. The results demonstrate that this is a robust and scalable method for implementing pedestrian navigation behaviour. Furthermore an algorithm for generating smooth and realistic pedestrian navigation paths that works well in both small and large spaces is presented. An adaptive smoothing function has been utilised to optimise the path used by pedestrian agents to navigate around in a complex dynamic environment. Optimised and un-optimised vectors maps obtained by applying or not such function are compared, and the results show that the optimized path generates a more realistic flow.
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.
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.
Pattern Recognition in Cytopathology for Papanicolaou Screening
(The Eurographics Association, 2010) Blackledge, Jonathan; Dubovitskiy, D. A.; John Collomosse and Ian Grimstead
A unique space oriented filer is presented in order to detect and isolate the cell of a nucleus for applications in cytopathology. A classification method for nuclei is then considered based on the application of a set of features which includes certain fractal parameters. Segmentation algorithms are considered in which a self-adjustable sharpening filter is designed to enhance object location. Although the methods discussed and the algorithms developed have a range of applications, in this work we focus on the engineering of a system for automating a Papanicolaou screening test using standard optical images
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.

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