EG UK Theory and Practice of Computer Graphics 2011

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Terrain Models for Mass Movement Erosion
(The Eurographics Association, 2011) Hudák, Matej; Durikovic, R.; Ian Grimstead and Hamish Carr
In this paper we present a particle-based method for large scale long time progressive simulation of terrain erosion containing wet granular particles. The wetting process and the propagation through granular material is based on defining the wetness value for each particle representing the amount of water absorbed by granular particles and stored between them, as was originally proposed by Rungjiratananon [RSKN08]. We extend this model by adding a non homogeneous material to simulate differences between different types of soil-like granular material, based on physical constants like stability, plasticity and wetness. With this approach we can create a physical animation of erosion process like mass movement or mass wasting.
Airborne Ultrasound Pulse Force Device for Palpation Simulation
(The Eurographics Association, 2011) Hung, Gary M.; John, Nigel W.; Ian Grimstead and Hamish Carr
This research is investigating the use of acoustic radiation pressure from ultrasound emitters to produce tactile feedback in medical simulators. An initial application would be to simulate a pulse palpation where the trainee doctor or nurse actively searches for a pulse with their fingers to locate an artery within the body. Our first steps towards achieving this aim are summarised below.
Memory Efficient Surface Reconstruction Based on Self Organising Maps
(The Eurographics Association, 2011) Kaye, David Paul; Ivrissimtzis, Ioannis; Ian Grimstead and Hamish Carr
We propose a memory efficient, scalable surface reconstruction algorithm based on self organising maps (SOMs). Following previous approaches to SOM based implicit surface reconstruction, the proposed SOM has the geometry of a regular grid and is trained with point samples extracted along the normals of the input data. The layer by layer training of the SOM makes the algorithm memory efficient and scalable as at no stage there is need to hold the entire SOM in memory. Experiments show that the proposed algorithm can support the training of the very large SOMs that are needed for richly detailed surface reconstructions.
Visualisation of Blockplay in Early Childhood
(The Eurographics Association, 2011) Albin-Clark, Adrian; Howard, T. L. J.; Anderson, B.; Ian Grimstead and Hamish Carr
Observation of young children is common in educational settings. For trainee practitioners however, access to children is infrequent, and even then, only small amounts of observable activity can be captured. We have developed a cross-platform software application to support observations made by pedagogical practitioners. Our system combines game-oriented technology: 3D graphics, animation, physics and classical game artificial intelligence. The stages of blockplay are used to represent the physical play of characters, and social play stages and egocentrism define their behaviour. We present the graphical side of the system including visualisations options that expose the underlying functionality. The prototype system Observation which we believe is the first to employ 3D interactive computer graphics for visualising early childhood play, is available for download and evaluation.
Visual Saliency for Smell Impulses and Application to Selective Rendering
(The Eurographics Association, 2011) Harvey, Carlo; Bashford-Rogers, Thomas E. W.; Debattista, Kurt; Chalmers, Alan; Ian Grimstead and Hamish Carr
A major challenge in generating high-fidelity virtual environments is to be able to provide interactive rates of realism. However this is very computationally demanding and only recently visual perception has been used in high-fidelity rendering to improve performance considerably by a series of novel exploitations; 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 various smells have on the visual attention of the user when free viewing a set of engineered images. We verify the worth of investigating these saccade shifts (fast movements of the eyes) due to attention distraction to a congruent smell object. By analysing the gaze points, we identify time spent attending a particular area of a scene. We also present a technique from measured data to remodulate traditional saliency maps of image features to account for the observed results. We show that smell provides an impulse on attention to affect perception in such a way that this can be used to guide selective rendering of scenes through use of the remodulated saliency maps.
Simple and Efficient Normal Encoding with Error Bounds
(The Eurographics Association, 2011) Schinko, Christoph; Ullrich, Torsten; Fellner, Dieter W.; Ian Grimstead and Hamish Carr
Normal maps and bump maps are commonly used techniques to make 3D scenes more realistic. Consequently, the efficient storage of normal vectors is an important task in computer graphics. This work presents a fast, lossy compression/decompression algorithm for arbitrary resolutions. The complete source code is listed in the appendix and is ready to use.
Remodelling of Botanical Trees for Real-Time Simulation
(The Eurographics Association, 2011) Reynolds, Daniel T.; Laycock, Stephen D.; Day, Andy M.; Ian Grimstead and Hamish Carr
This paper proposes a technique to use virtual trees created with an industry recognised modelling tool. Initially the skeletal structure is extracted and processed to generate a continuous mesh suitable for high quality, real-time rendering and simulation. Utilising the inherent hierarchical structure of botanical trees, the bone system is calculated from existing, low quality geometry. Once an ordered skeleton is available, a low resolution surface is created around the form as a single continuous mesh providing smooth, continuous connections where branches diverge, avoiding artefacts introduced by overlaid surfaces. Creation of the vertices relative to the skeletal structure ensures no miss-classification in assigning bone influence, allowing for realistic animation and effective mesh refinement introduced dynamically using GPU based techniques.
Advantages of 3D Extraction and Spatial Awareness within a Videoconferencing Environment
(The Eurographics Association, 2011) Rodriguez-Frias, Myrna M.; Morris, Tim; Turner, Martin; Rowley, Andrew; Ian Grimstead and Hamish Carr
This work-in-progress paper describes some of the issues, and lists proposed use-case scenarios, for the development of a real-time multi-participant 3D enhanced videoconferencing system. We are interested in creating a framework capable of reconstructing an approximate 3D model of the physical environment, from a collection of images taken via the same system from probably unknown camera viewpoints. This reconstruction framework creates a partial 3D world that is embedded back within the videoconferencing environment and transmitted to all participants. We hypothesise that detailed 3D positional information combined with this augmented 3D world information of remote sites, can be useful to participants over and above the usual audio and video streams; it is believed that 3D reconstruction can be a rich tool to enable analysis and spatial awareness, moreover facilitating interactions with participants at remote sites.
Interactive Computer Visualisations of Time and Place
(The Eurographics Association, 2011) Fishenden, Jerry; Ian Grimstead and Hamish Carr
This paper describes research into the development of a composition portfolio themed on interactive computer-based visualisations of time and place. The application of various computer graphics techniques are discussed including pixel shaders, particle systems, plasma and Perlin Noise.
A Desktop Multi-Touch Interface for Posing Characters
(The Eurographics Association, 2011) Stephenson, Ian; Ian Grimstead and Hamish Carr
Multi-touch, direct manipulation interfaces have become common in mobile media applications, but their use on the desktop is limited. In this paper we propose that multi touch direct manipulation is well suited to the posing of animated characters using inverse kinematics, and demonstrate how it can be implemented in a desktop application, by the addition of commodity mobile touch devices. We also describe how the multi-touch display software developed for this system can be integrated into a number of other applications.
Morphological Analysis from Images of Hyphal Growth using a Fractional Dynamic Model
(The Eurographics Association, 2011) Blackledge, Jonathan M.; Barry, D. J.; Ian Grimstead and Hamish Carr
The development of methods capable of accurately characterising the morphology of filamentous microbes represents a significant challenge to biotechnologists. This is because the productivity of many industrial fermentation processes is heavily dependent on the morphological form adopted by an organism. It is therefore of significant value if a quantitative model and associated metric(s) for morphological forms determined by complex phenotypes can be determined non-invasively, e.g. through image analysis. Specific interest is in the quantification of the branching behaviour of an organism. This is due to the link between branching frequency, biomass and metabolite production. In this paper we present a model for three-dimensional microbial growth that is based on a fractional dynamic model involving separable coordinate geometry. This provides the focus for the approach reported in this paper where microbial growth can be quantified using a sample microscopic digital image. In particular, we study the fractal dimension of fungal mycelial structures by generating a 'fractal signal' based on the object boundary. In the analysis of a population of Aspergillus oryzae mycelia, both the fractal dimension and hyphal growth unit are found to increase together over time. Further, through an extensive analysis of different populations of Penicillium chrysogenum and A. oryzae mycelia, cultivated under a variety of different conditions, we show that there is a statistically significant logarithmic correlation between the boundary fractal dimension and hyphal growth unit.
Model and Visualise the Relationship between Energy Consumption and Temperature Distribution in Cold Rooms
(The Eurographics Association, 2011) Ma, Ji; Murphy, D.; O'Mathuna, C.; Hayes, M.; Provan, G.; Ian Grimstead and Hamish Carr
In the area of food and pharmacy cold storage, temperature distribution is considered as a key factor. Inappropriate distribution of temperature during the cooling process in cold rooms will cause the deterioration of the quality of products and therefore shorten their life-span. In practice, in order to maintain the distribution of temperature at an appropriate level, large amount of electrical energy has to be consumed to cool down the volume of space, based on the reading of a single temperature sensor placed in every cold room. However, it is not clear and visible that what is the change of energy consumption and temperature distribution over time. It lacks of effective tools to visualise such a phenomenon. In this poster, we initially present a solution which combines a visualisation tool with a Computational Fluid Dynamics (CFD) model together to enable users to explore such phenomenon.
Pixel-Level Algorithms for Drawing Curves
(The Eurographics Association, 2011) Liu, Yong Kui; Wang, Peng Jie; Zhao, Dan Dan; Spelic, Denis; Mongus, Domen; Zalik, Borut; Ian Grimstead and Hamish Carr
This paper introduces new pixel level algorithms for parametric curves. The optimal value of the steps is first derived when rastrerizing parametric curves. A double-step algorithm using only integer arithmetic is presented to minimize the problem of oversampling. The algorithms for parametric curves have been implemented also on GPU. Through experiments we confirmed that the performance of this new algorithm is superior to previous algorithms.
Building a Video Wall for Earth Observation Data
(The Eurographics Association, 2011) Bennett, Victoria; Haffegee, Adrian; Matthews, Brian; Nagella, Srikanth; Shaw, Andrew; Styles, Jon; Ian Grimstead and Hamish Carr
Earth observation satellites are generating large amounts of data as they monitor the earth' environment. Large scale visualisation represents a powerful mechanism to explore and communicate this data; however, conventional tools and screens are limited by their size, while large shared screens are limited in their resolution. In this paper, we describe the motivations and design for a multi-panel video wall facility for the new International Space Innovation Centre. We further describe two visualisation applications which have been designed to demonstrate some of the potential of this wall to share data visualisations with a large audience, while providing a highly detailed view on the data.
Evaluation of a Reconfigurable Tangible Device for Collaborative Manipulation of Objects in Virtual Reality
(The Eurographics Association, 2011) Aguerreche, Laurent; Duval, Thierry; Lécuyer, Anatole; Ian Grimstead and Hamish Carr
In this paper we introduce an evaluation of a Reconfigurable Tangible Device (RTD) for collaborative manipulation of objects in virtual environments. The considered RTD, called RTD-3, has a triangular shape that naturally provides three points of manipulation. The shape of the tangible triangle can be reconfigured at any time as its branches can be shrunk or stretched by users at will. Thanks to this simple shape the RTD-3 can be easily attached to any 3D virtual object and fully defines its virtual motion in 6 Degrees of Freedom. We have conducted an experiment to assess the potential of the RTD-3 and compare it with classical techniques used for collaborative virtual manipulation. Participants were asked to manipulate and assemble, in a collaborative manner, virtual parts. Our results suggest that the physical manipulation proposed by the tangible device is significantly preferred by participants in terms of immersion, realism of interaction and preparation to the real task. Although our approach is slightly slower than the other tested methods, it produces the fewest collisions.
Dynamic Video Face Transformation Using Multilinear and Autoregressive Models
(The Eurographics Association, 2011) Tiddeman, Bernard; Hunter, David; Perrett, David; Ian Grimstead and Hamish Carr
In this paper we present a prototype system for altering perceived attributes of faces in video sequences, such as the apparent age, sex or emotional state. The system uses multilinear models to decompose the parameters coding for each frame into separate pose and identity parameters. The multilinear model is learnt automatically from the training video data. Statistical models of group identity are then used to alter the identity parameters from one group to another (e.g. from male to female). An autoregressive model is learnt from the pose parameters, and this is applied to alter the dynamics. We have tested our system on a small dataset (for altering apparent gender) with encouraging preliminary results.
A Low-Cost Single-Pixel Thermographic Camera
(The Eurographics Association, 2011) Bauer, Florian; Loviscach, Jörn; Ian Grimstead and Hamish Carr
A working prototype of single-pixel thermographic camera which can be built for 100 Euros is presented. It is based on a pyrometer's sensor (thermopile with optics) and two mirrors mounted on servos to scan horizontally and vertically. Thanks to simple yet powerful filtering, the measurement proceeds at a speed of 5 ms per pixel even though the sensor has an actual response time of t90 ~60 ms. The scan for the resulting sharp image of 80x80 pixels takes one minute. We discuss further improvements to create a product suitable for facade thermography.
Compositing Shaders in X3D
(The Eurographics Association, 2011) Kamburelis, Michalis; Ian Grimstead and Hamish Carr
We present a new approach for implementing effects using the GPU shading languages. Our effects seamlessly cooperate with each other and with the shaders used internally by the 3D application. Thus the effects are reusable, work in various combinations and under all lighting and texture conditions. We have designed our effects to fit naturally in 3D scene graph formats, in particular we present a number of extensions to the X3D standard. Our extensions nicely integrate shader effects with X3D concepts like shapes, light sources and textures.
Enabling Visualization of Massive Datasets Through MPP Database Architecture
(The Eurographics Association, 2011) Al-Naser, Aqeel; Rasheed, Masroor; Brooke, John; Irving, Duncan; Ian Grimstead and Hamish Carr
We are developing a novel visualization architecture which is specifically designed to render very large (terabyte scale) datasets. Our method differs from the classic visualization pipeline of Harber and McNabb. In particular we eliminate the need to create geometric objects, for example surfaces composed of polygons, as a stage before rendering. Such objects require specialist HPC servers for their creation and manipulation; our solution eliminates the need for such servers. We replace the geometric objects by structures stored and tagged in a database next to the original dataset; we call these Spatially Registered Data Structures (SRDS). Such structures are linked to a single rendering pipeline through the on-the-fly creation of a Feature Embedded Spatial Volume (FESVo). This solution exploits recently developed capabilities of in-database Massive Parallel Processing (MPP) and parallel data streaming, together with the rapidly developing capabilities of GPUs. We describe an early prototype of an architecture applied to seismic data from the oil and gas industry.

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