EG UK Theory and Practice of Computer Graphics

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12DoF Interaction for Scientific Visualisation
(The Eurographics Association, 2017) Turner, Martin J.; Morris, Tim; Sandoval, Mario; Tao Ruan Wan and Franck Vidal
This short extended abstract investigates human-computer interactions in relation to a specific Six Degree of Freedom (6DoF) input device; described is the driver development and calibration required for a novel piece of hardware; and after initial user tests and a questionnaire of satisfaction, we consider areas for further research. This abstract concludes with a discussion of the design and use of dual-6DoF input devices and from feedback how new interaction modes will be exploited.
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.
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.
3D Visualisations Should Not be Displayed Alone - Encouraging a Need for Multivocality in Visualisation
(The Eurographics Association, 2021) Roberts, Jonathan C.; Mearman, Joseph W.; Butcher, Peter W. S.; Al-Maneea, Hayder M.; Ritsos, Panagiotis D.; Xu, Kai and Turner, Martin
We believe that 3D visualisations should not be used alone; by coincidentally displaying alternative views the user can gain the best understanding of all situations. The different presentations signify manifold meanings and afford different tasks. Natural 3D worlds implicitly tell many stories. For instance, walking into a living room, seeing the TV, types of magazines, pictures on the wall, tells us much about the occupiers: their occupation, standards of living, taste in design, whether they have kids, and so on. How can we similarly create rich and diverse 3D visualisation presentations? How can we create visualisations that allow people to understand different stories from the data? In a multivariate 2D visualisation a developer may coordinate and link many views together to provide exploratory visualisation functionality. But how can this be achieved in 3D and in immersive visualisations? Different visualisation types, each have specific uses, and each has the potential to tell or evoke a different story. Through several use-cases, we discuss challenges of 3D visualisation, and present our argument for concurrent and coordinated visualisations of alternative styles, and encourage developers to consider using alternative representations with any 3D view, even if that view is displayed in a virtual, augmented or mixed reality setup.
Accelerating Raycasting Utilizing Volume Segmentation of Industrial CT Data
(The Eurographics Association, 2009) Frey, Steffen; Ertl, Thomas; Wen Tang and John Collomosse
We propose a flexible acceleration technique for raycasting targeted at industrial CT data and the context of material deficiency checking. Utilizing volume segmentation that is typically employed for object analysis, GPU raycasting can be accelerated significantly using a novel data structure that is integrated into the volume to improve the responsiveness for the interactive, visual inspection of high-resolution, high-precision data. Our acceleration approach is designed to cause no extra texture lookups and to produce only marginal computational and storage overhead. Despite the fact that the data structure is integrated into the volume, the graphics card's hardware can still be used for trilinear interpolation of density values without producing incorrect results. The presented method can further easily be utilized in combination with out-of-core approaches and distributed volume rendering schemes.
Accelerating Surface Tension Calculation in SPH via Particle Classification and Monte Carlo Integration
(The Eurographics Association, 2019) Zorrilla, Fernando; Sappl, Johannes; Rauch, Wolfgang; Harders, Matthias; Vidal, Franck P. and Tam, Gary K. L. and Roberts, Jonathan C.
Surface tension has a strong influence on the shape of fluid interfaces. We propose a method to calculate the corresponding forces efficiently. In contrast to several previous approaches, we discriminate to this end between surface and non-surface SPH particles. Our method effectively smooths the fluid interface, minimizing its curvature. We make use of an approach inspired by Monte Carlo integration to estimate local normals as well as curvatures, based on which the force can be calculated. The technique is applicable, but not limited to 2D and 3D simulations, and can be coupled with any common SPH formulation. It outperforms prior approaches with regard to total computation time per time step, while being stable and avoiding artifacts.
Accurate and Marker-less Head Tracking Using Depth Sensors
(The Eurographics Association, 2013) Breidt, Martin; Bülthoff, Heinrich H.; Curio, Cristóbal; Silvester Czanner and Wen Tang
Parameterized, high-fidelity 3D surface models can not only be used for rendering animations in the context of Computer Graphics (CG), but have become increasingly popular for analyzing data, and thus making these accessible to CG systems in an Analysis-by-Synthesis loop. In this paper, we utilize this concept for accurate head tracking by fitting a statistical 3D model to marker-less face data acquired with a low-cost depth sensor, and demonstrate its robustness in a challenging car driving scenario. We compute 3D head position and orientation with a mesh-based 3D shape matching algorithm that is independent of person identity and sensor type, and at the same time robust to facial expressions, speech, partial occlusion and illumination changes. Different strategies for obtaining the 3D face model are evaluated, trading off computational complexity and accuracy. Ground truth data for head pose are obtained from simultaneous marker-based tracking. Average tracking errors are below 6mm for head position and below 2.5 for head orientation, demonstrating the system's potential to be used as part of a non-intrusive head tracking system for use in Augmented Reality or driver assistance systems.
Acquisition, Representation and Rendering of Real-World Models using Polynomial Texture Maps in 3D
(The Eurographics Association, 2013) Vassallo, Elaine; Spina, Sandro; Debattista, Kurt; Silvester Czanner and Wen Tang
The ability to represent real-world objects digitally in a realistic manner is an indispensable tool for many applications. This paper proposes a method for acquiring, processing, representing, and rendering these digital representations. Acquisition can be divided into two processes: acquiring the 3D geometry of the object, and obtaining the texture and reflectance behaviour of the object. Our work explores the possibility of using Microsoft's Kinect sensor to acquire the 3D geometry, by registration of data captured from different viewpoints. The Kinect sensor itself is used to acquire texture and reflectance information which is represented using multiple Polynomial Texture Maps. We present processing pipelines for both geometry and texture, and finally our work examines how the acquired and processed geometry, texture, and reflectance behaviour information can be mapped together in 3D, allowing the user to view the object from different viewpoints while being able to interactively change light direction. Varying light direction uncovers details of the object which would not have been possible to observe using a single, fixed, light direction. This is useful in many scenarios, amongst which is the examination of cultural heritage artifacts with surface variations.
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.
An Adaptive Sampling Approach to Incompressible Particle-Based Fluid
(The Eurographics Association, 2009) Hong, Woosuck; House, Donald H.; Keyser, John; Wen Tang and John Collomosse
We describe an adaptive particle-based technique for simulating incompressible fluid that uses an octree structure to compute inter-particle interactions and to compute the pressure field. Our method extends the hybrid Flip technique by supporting adaptive splitting and merging of fluid particles, and adaptive spatial sampling for the reconstruction of the velocity and pressure fields. Particle splitting allows a detailed sampling of fluid momentum in regions of complex flow. Particle merging, in regions of smooth flow, reduces memory and computational overhead. The octree supporting field-based calculations is adapted to provide a fine spatial reconstruction where particles are small and a coarse reconstruction where particles are large. This scheme places computational resources where they are most needed, to handle both flow and surface complexity. Thus, incompressibility can be enforced even in very small, but highly turbulent areas. Simultaneously, the level of detail is very high in these areas, allowing the direct support of tiny splashes and small-scale surface tension effects. This produces a finely detailed and realistic representation of surface motion.
Adi's Maze and the Research Arcade: A Long-term Study on the Impact of Gendered Representation on Player Preferences
(The Eurographics Association, 2021) Headleand, Christopher J.; Davies, Bethany; Williams, Benjamin; Xu, Kai and Turner, Martin
Gender representation in games is a much discussed topic in the field of games design. A number of papers have explored the issues around sexist, and sexualised representation, and there even evidence that the assumed gender of a character has an impact on player behaviour. We introduce Adi's maze, a simple arcade game with 4 selectable characters, with male, female, and ambiguous gendered representation. In the game, the player has to collect coins in a maze while avoiding enemy NPCs in a similar format to the popular 1980's game Pac-Man. Regardless of the selected character, the player has the same objective to complete. We installed this game on two publicly accessible arcade machines (the Research Arcade) and left them in situ for 18 months. We collected all data regarding the character selection and player behaviour and we report the results from this study. Furthermore, we report insights from the development of the research arcade, and comment on it's effectiveness as a research tool.
Advanced, Automatic Stream Surface Seeding and Filtering
(The Eurographics Association, 2012) Edmunds, Matt; Laramee, Robert S.; Chen, Guoning; Zhang, Eugene; Max, Nelson; Hamish Carr and Silvester Czanner
The placement or seeding of stream surfaces in 3D flow fields faces a number of challenges. These challenges include perception, occlusion, and the appropriate representation of flow characteristics. A variety of streamline seeding approaches exist, little corresponding work is presented for stream surfaces. We present a novel automatic stream surface seeding and filtering algorithm. Our approach is designed to capture the characteristics of the flow utilizing illustrative techniques to alleviate occlusion and provide options for filtering. We define and prioritize a set of seeding curves at the domain boundaries from isolines computed from a derived scalar field. We detail the generation of an initial set of surfaces from the set of seeding curves, and discuss a technique for effective surface termination. We then present an algorithm that automatically seeds new interior surfaces, to represent locations not captured by the boundary seeding, at a user specified separation from the initial surface set. The results demonstrate satisfactory domain coverage and effective visualizations on a variety of simulations.
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.
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.
Aesthetic-Interaction: Exploring the Importance of the Visual Aesthetic in the Creation of Engaging Photorealistic VR Environments
(The Eurographics Association, 2009) Carroll, Fiona; Wen Tang and John Collomosse
Nearly forty years since its conception, the medium of VR is still an enigma. In many ways, it is a medium that still lacks its own uniform language. VR, and particularly photorealistic VR, is a medium that is so occupied in developing its technological capabilities that its other hidden strengths have been neglected. The research presented in this paper is therefore interested in building a more holistic understanding of the "language" of VR, and aims to look beyond the technological in order to explore the creative and experiential side of VR. The goal of the paper is to cross fertilise the fields of HCI, photorealistic virtual reality and visual aesthetics. In it, the author focuses on the design of an aesthetic-interaction and in doing so, implements a comparative study to explore how the strategic patterning of the aesthetic elements (particularly colour) within the photorealistic VR environment can ensure a more engaging VR experience. In conclusion, the author claims that the next generation design of photorealistic VR experiences should consider a balanced combination of both science and art. It highlights that aesthetics can play as important a role as the development of new and more efficient technologies in getting to the heart of the "engaging" photorealistic VR experience.
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.
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.
An Aliasing Theory of Shadow Mapping
(The Eurographics Association, 2009) Zhang, Fan; Zhao, Chong; Sun, Hanqiu; Wen Tang and John Collomosse
Shadow mapping is a popular image-based technique for real-time shadow rendering. Although numerous improvements have been made to help anti-aliasing in shadow mapping, there is a lack of mathematical tools that allow us to quantitatively analyze aliasing errors in its variants. In this paper, we establish an aliasing theory to achieve this goal. A generalized representation of aliasing errors is derived from a pure mathematical point of view. The major highlight of this representation is the ability of quantifying the aliasing error at any position for general view-light configurations. On the contrary, due to the geometric assumptions used in the computational model, previous work analyzes the aliasing only along the view direction in the simplest case where the light and view directions are orthogonal. Subsequently, as a direct application of our theory, we present a comparison of aliasing distributions in a few representative variants of perspective shadow maps. We believe that these theoretical results are useful to better understand shadow mapping, and thus inspire people to develop novel techniques in this area.
Amplitude Modulated Line-Based Halftoning
(The Eurographics Association, 2016) Ahmed, Abdalla G. M.; Deussen, Oliver; Cagatay Turkay and Tao Ruan Wan
We present a new approach for line-based halftoning of images, where banks of waveforms are modulated by the gray levels of the rendered image. We present examples that employ sinusoidal and triangular waveforms, and highlight some applications, including stylized rendering, halftoning in line-based devices, and education.
Analyzing and Visualizing Multivariate Volumetric Scalar Data and Their Uncertainties
(The Eurographics Association, 2012) Ma, Ji; Murphy, D.; O'Mathuna, C.; Hayes, M.; Provan, G.; Hamish Carr and Silvester Czanner
Data sets from the real world and most scientific simulations are known to be imperfect, often incorporating uncertainty information. Exploration and analysis of such variable data can lead to inaccurate or even incorrect results and inferences. As a powerful tool to communicate the data with users, an effective visualization system should present and inform users of the uncertainty information existing in the data. While some research has been conducted on visualizing uncertainty in spatio-temporal data and univariate data, little work has been reported on multivariate data. In addition, there are two main disadvantages in the existing uncertainty visualization methods for volumetric data. First, they rely heavily on the human perceptual system to recognize the uncertainty information, lacking the capability to depict them quantitatively. Second, they often present large amounts of diverse information in a single display, which may result in visual clutter and occlusion. In this paper, we present our hybrid framework that combines both information visualization techniques and scientific visualization techniques together to allow users to interactively specify features of interest, quantitatively explore and analyze the multivariate volumetric data and their uncertainties as well as localize features in the 3D object space. In comparison with those existing methods, we argue that our method not only allows users to quantitatively visualize the uncertainties within multivariate volumetric data, but also yields a clearer data presentation and facilitates a greater level of visual data analysis. We demonstrate the effectiveness of our framework by reporting a case study from the OpenGGCM (Open Geospace General Circulation Model) simulation in space science application domain.

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