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Item Virtual Reality: A Literature Review and Metrics-based Classification(The Eurographics Association, 2018) Ankomah, Peter; Vangorp, Peter; {Tam, Gary K. L. and Vidal, FranckThis paper presents a multi-disciplinary overview of research evaluating virtual reality (VR). The main aim is to review and classify VR research based on several metrics: presence and immersion, navigation and interaction, knowledge improvement, performance and usability. With the continuous development and consumerisation of VR, several application domains have studied the impact of VR as an enhanced alternative environment for performing tasks. However, VR experiment results often cannot be generalised but require specific datasets and tasks suited to each domain. This review and classification of VR metrics presents an alternative metrics-based view of VR experiments and research.Item Optimising Underwater Environments for Mobile VR(The Eurographics Association, 2019) Cenydd, Llyr ap; Headleand, Christopher; Vidal, Franck P. and Tam, Gary K. L. and Roberts, Jonathan C.Mobile Virtual Reality (VR) has advanced considerably in the last few years, driven by advances in smartphone technology. There are now a number of commercial offerings available, from smartphone powered headsets to standalone units with full positional tracking. Similarly best practices in VR have matured quickly, facilitating comfortable and immersive VR experiences. There remains however many optimisation challenges when working with these devices, as while the need to render at high frame rates is universal, the hardware is limited by both computational power and battery capacity. There is also often a requirement that apps run smoothly across a wide variety of headsets. In this paper, we describe lessons learned in rendering and optimising underwater environments for mobile VR, based on our experience developing the popular aquatic safari application 'Ocean Rift'. We start by analyzing essential best practices for mobile app development, before describing low-cost techniques for creating immersive underwater environments. While some techniques discussed are universal to modern mobile VR development, we also consider issues that are unique to underwater applications.Item Screen Space Particle Selection(The Eurographics Association, 2018) Köster, Marcel; Krüger, Antonio; {Tam, Gary K. L. and Vidal, FranckAnalyses of large 3D particle datasets typically involve many different exploration and visualization steps. Interactive exploration techniques are essential to reveal and select interesting subsets like clusters or other sophisticated structures. State-of-the-art techniques allow for context-aware selections that can be refined dynamically. However, these techniques require large amounts of memory and have high computational complexity which heavily limits their applicability to large datasets. We propose a novel, massively parallel particle selection method that is easy to implement and has a processing complexity of O(n*k) (where n is the number of particles and k the maximum number of neighbors per particle) and requires only O(n) memory. Furthermore, our algorithm is designed for GPUs and performs a selection step in several milliseconds while still being able to achieve high-quality results.Item Controlling 3D Visualisations with Multiple Degrees of Freedom(The Eurographics Association, 2019) Sandoval, Mario; Morris, Tim; Turner, Martin; Vidal, Franck P. and Tam, Gary K. L. and Roberts, Jonathan C.In this paper, the two major components of a new multi-layer framework ideal for two-handed interaction in desktop virtual environments called Library for Interactive Settings of User-Mode (LISU) are explained. In addition, we evaluate LISU performance with a group of participants and we report some of our initial results by giving an analysis of user experiences, and interaction speed.Item Evolutionary Interactive Analysis of MRI Gastric Images Using a Multiobjective Cooperative-coevolution Scheme(The Eurographics Association, 2018) Al-Maliki, Shatha F.; Lutton, Évelyne; Boué, François; Vidal, Franck; {Tam, Gary K. L. and Vidal, FranckIn this study, we combine computer vision and visualisation/data exploration to analyse magnetic resonance imaging (MRI) data and detect garden peas inside the stomach. It is a preliminary objective of a larger project that aims to understand the kinetics of gastric emptying. We propose to perform the image analysis task as a multi-objective optimisation. A set of 7 equally important objectives are proposed to characterise peas. We rely on a cooperation co-evolution algorithm called 'Fly Algorithm' implemented using NSGA-II. The Fly Algorithm is a specific case of the 'Parisian Approach' where the solution of an optimisation problem is represented as a set of individuals (e.g. the whole population) instead of a single individual (the best one) as in typical evolutionary algorithms (EAs). NSGA-II is a popular EA used to solve multi-objective optimisation problems. The output of the optimisation is a succession of datasets that progressively approximate the Pareto front, which needs to be understood and explored by the end-user. Using interactive Information Visualisation (InfoVis) and clustering techniques, peas are then semi-automatically segmented.Item When Size Matters: Towards Evaluating Perceivability of Choropleths(The Eurographics Association, 2018) McNabb, Liam; Laramee, Robert S.; Wilson, Max; {Tam, Gary K. L. and Vidal, FranckChoropleth maps are an invaluable visualization type for mapping geo-spatial data. One advantage to a choropleth map over other geospatial visualizations such as cartograms is the familiarity of a non-distorted landmass. However, this causes challenges when an area becomes too small in order to accurately perceive the underlying color. When does size matter in a choropleth map? We conduct an experiment to verify the relationship between choropleth maps, their underlying color map, and a user's perceivability. We do this by testing a user's perception of color relative to an administrative area's size within a choropleth map, as well as user-preference of fixed-locale maps with enforced minimum areas. Based on this initial experiment we can make the first recommendations with respect to a unit area's minimum size in order to be perceivably useful.Item Data Painter: A Tool for Colormap Interaction(The Eurographics Association, 2017) Nagoor, Omniah H.; Borgo, Rita; Jones, Mark W.; Tao Ruan Wan and Franck VidalThe choice of a mapping from data to color should involve careful consideration in order to maximize the user understanding of the underlying data. It is desirable for features within the data to be visually separable and identifiable. Current practice involves selecting a mapping from predefined colormaps or coding specific colormaps using software such as MATLAB. The purposes of this paper are to introduce interactive operations for colormaps that enable users to create more visually distinguishable pixel based visualizations, and to describe our tool, Data Painter, that provides a fast, easy to use framework for defining these color mappings. We demonstrate the use of the tool to create colormaps for various application areas and compare to existing color mapping methods. We present a new objective measure to evaluate their efficacyItem GPU-Assisted Scatterplots for Millions of Call Events(The Eurographics Association, 2018) Rees, Dylan; Roberts, Richard C.; Laramee, Robert S.; Brookes, Paul; D'Cruze, Tony; Smith, Gary A.; {Tam, Gary K. L. and Vidal, FranckWith four percent of the working population employed in call centers in both the United States and the UK, the contact center industry represents a sizable proportion of modern industrial landscapes. As with most modern industries, data collection is de rigueur, producing gigabytes of call records that require analysis. The scatterplot is a well established and understood form of data visualization dating back to the 17th century. In this paper we present an application for visualizing large call centre data sets using hardware-accelerated scatterplots. The application utilizes a commodity graphics card to enable visualization of a month's worth of data, enabling fast filtering of multiple attributes. Filtering is implemented using the Open Computing Language (OpenCL), providing significant performance improvement over traditional methods. We demonstrate the value of our application for exploration and analysis of millions of call events from a real-world industry partner. Domain expert feedback from our industrial partners is reported.Item Virtual Reality Callouts - Demonstrating Knowledge With Spatial-Related Textual Information(The Eurographics Association, 2019) Horst, Robin; Degreif, Anika; Mathy, Marvin; Dörner, Ralf; Vidal, Franck P. and Tam, Gary K. L. and Roberts, Jonathan C.Virtual (VR) and augmented reality (AR) can bring an added value during the demonstration of knowledge, as for example within an interactive research demo. Callouts are strings of text which are connected by a line to a specific feature of an object. These visual annotations can be used during such demos and can be placed in different kinds of media, such as illustrations, technical drawings, images and videos. Callouts are also used in virtual 3D environments to anchor textual information to a specific point in space. Therefore they can be a valuable tool for virtually demonstrating knowledge. The alignment of callouts in such information rich environments is an elemental factor within the view management of the VR scene. In this paper we propose a concept for interactive microlearning application for knowledge demonstration that uses callouts as a fundamental element. We distinguish three types of interactive callout-representations by their alignment relative to the user, for being static or dynamic in their position and orientation. Within an implementation of the different callout versions we show the feasibility and in a user study we indicate a user-preference towards static positioned callouts.Item Towards a Tool for the Creation of Micro-visualisations(The Eurographics Association, 2019) Jackson, James; Ritsos, Panagiotis; Roberts, Jonathan; Vidal, Franck P. and Tam, Gary K. L. and Roberts, Jonathan C.As the every day use of mobile and small screen devices becomes more common, it is necessary to explore how we can visualise data effectively in small design spaces. These screens are often used in situations where it is necessary to convey information in a concise, readable, reliable and visually appealing way. Our work focuses on the design and development of a tool to facilitate the creation and manipulation of new micro-visualisations. The results show that the tool is suitable for creating large number of outputs quickly and efficiently.