Search Results

Now showing 1 - 10 of 60
  • Item
    Study of the Influence of User Characteristics on the Virtual Reality Presence
    (The Eurographics Association, 2018) Mayor, Jesús; Sánchez, Alberto; Raya, Laura; García-Fernández, Ignacio and Ureña, Carlos
    In recent years, virtual reality has grown a lot in different areas of application, including ludic, social and research, being used by a large and growing number of users with different profiles. Presence is one of the most distinctive and important features of a virtual reality experience. The aim of this article is to study the most suitable areas of application for users and to analyze the influence of different characteristics of the user's profile in the perceived presence. We have tested the interest applications indicated by 159 subjects and we have designed an immersive virtual reality experience, testing the behavior and performance of 48 users. The results obtained show that gender can influence the perceptual sensation of presence in these types of virtual environments.
  • Item
    A Virtual Character Posing System based on Reconfigurable Tangible User Interfaces and Immersive Virtual Reality
    (The Eurographics Association, 2018) Cannavò, A.; Lamberti, F.; Livesu, Marco and Pintore, Gianni and Signoroni, Alberto
    Computer animation and, particularly, virtual character animation, are very time consuming and skill-intensive tasks, which require animators to work with sophisticated user interfaces. Tangible user interfaces (TUIs) already proved to be capable of making character animation more intuitive, and possibly more efficient, by leveraging the affordances provided by physical props that mimic the structure of virtual counterparts. The main downside of existing TUI-based animation solutions is the reduced accuracy, which is due partly to the use of mechanical parts, partly to the fact that, despite the adoption of a 3D input, users still have to work with a 2D output (usually represented by one or more views displayed on a screen). However, output methods that are natively 3D, e.g., based on virtual reality (VR), have been already exploited in different ways within computer animation scenarios. By moving from the above considerations and by building upon an existing work, this paper proposes a VR-based character animation system that combines the advantages of TUIs with the improved spatial awareness, enhanced visualization and better control on the observation point in the virtual space ensured by immersive VR. Results of a user study with both skilled and unskilled users showed a marked preference for the devised system, which was judged as more intuitive than that in the reference work, and allowed users to pose a virtual character in a lower time and with a higher accuracy.
  • Item
    Modelling the Fluid-Boundary Interaction in SPH
    (The Eurographics Association, 2018) Perea, Juan J.; Cordero, Juan M.; García-Fernández, Ignacio and Ureña, Carlos
    Smoothed Particle Hydrodynamics (SPH) is a numerical method based on mutually interacting meshfree particles, and has been widely applied to fluid simulation in Computer Graphics. Originally SPH does not define the behaviour of the particle system in the contour, so the different variants of SPH have been solving this deficiency with different techniques. Some of these techniques are based on fictitious forces, specular particles or semi-analytic fields. However, all these proposals present a drawback, that are may introduce additional inaccuracy as a divergent behaviour of the particle dynamics or an artificial separation between the fluid limits and the contour. To solve these limitations at this paper presents a new technique based on contour particles that are used during simulation to model the interaction with the fluid. The use of contour particles had already been used in other works to construct the contour like a particle layer. That solution presents problems especially when increasing the complexity of the contour shape. In addition, unlike other techniques, this paper presents an additional advantage, the possibility of obtaining all the dynamic magnitudes for improving efficiency and versatility.
  • Item
    A Procedural Approach for Thermal Visualization on Buildings
    (The Eurographics Association, 2018) Muñoz, David; Besuievsky, Gonzalo; Patow, Gustavo A.; García-Fernández, Ignacio and Ureña, Carlos
    Thermal behaviour analysis on buildings is an important goal for all tasks involving energy flow simulation in urban environments. One of the most widely used simplified thermal models is based on an electrical analogy, where nodes are set to simulate and solve a circuit network. In this paper we propose a procedural approach for automatically locate the nodes of the circuit, according to the building structure. We provide a conceptual technique to efficiently visualize thermal variations over time in buildings. We show that we can simulate and visually represent the variations of the interior temperatures of a building over a period of time. We believe that the technique could be helpful for rapid analysis for changing building parameters, such as materials, dimensions or number of floors.
  • Item
    Hyperquadrics for Shape Analysis of 3D Nanoscale Reconstructions of Brain Cell Nuclear Envelopes
    (The Eurographics Association, 2018) Agus, M.; Calì, C.; Morales, A. Tapia; Lehväslaiho, H. O.; Magistretti, P. J.; Gobbetti, E.; Hadwiger, M.; Livesu, Marco and Pintore, Gianni and Signoroni, Alberto
    Shape analysis of cell nuclei is becoming increasingly important in biology and medicine. Recent results have identified that the significant variability in shape and size of nuclei has an important impact on many biological processes. Current analysis techniques involve automatic methods for detection and segmentation of histology and microscopy images, and are mostly performed in 2D. Methods for 3D shape analysis, made possible by emerging acquisition methods capable to provide nanometric-scale 3D reconstructions, are, however, still at an early stage, and often assume a simple spherical shape. We introduce here a framework for analyzing 3D nanoscale reconstructions of nuclei of brain cells (mostly neurons), obtained by semiautomatic segmentation of electron micrographs. Our method considers an implicit parametric representation customizing the hyperquadrics formulation of convex shapes. Point clouds of nuclear envelopes, extracted from image data, are fitted to our parametrized model, which is then used for performing statistical analysis and shape comparisons. We report on the preliminary analysis of a collection of 92 nuclei of brain cells obtained from a sample of the somatosensory cortex of a juvenile rat.
  • Item
    Pixel-based Wake Interaction and Power Estimation for a Wind Farm with Irregular Boundary
    (The Eurographics Association, 2018) Ohlsen, G.; Ruiz-Salguero, O.; Full, T.; Acosta, D.; Livesu, Marco and Pintore, Gianni and Signoroni, Alberto
    In the domain of generation of wind turbine energy, it is central to correctly estimate the interactions among the various turbines in a wind turbine farm. The spatial super-position of turbine wind wakes determines the wind conditions that each turbine in the farm is exposed to and its power output. The current state of the art represents the turbine wakes as a 2D real-valued polygonal trapezoid. The interactions among wakes imply Boolean operations among many trapezoids, producing an intractable fragmentation of the wake intersection and domain regions. The plan (2D) view of the terrain with this wake polygon fragmentation is then used to estimate the effective wind that each turbine receives. This calculation leads to cumbersome computation, which is even more impractical if 3D representations of the terrain, wakes and wind are needed. In response to these limitations, this manuscript presents a method in which the 2D turbine wakes are located on a terrain with holes and exclusion zones bounded by 2D polygons, considering wind direction and turbine array basic specifications. Then, a discretized or pixel approximation of the terrain and wake superposition is calculated using discrete levels of the turbine velocity deficits. This process allows a practical approximation of the power output of each turbine and of the full turbine set. The wake interaction and terrain boundaries are then texture - mapped onto the 3D representation of the terrain, for visualization purposes. As an application, an example of a complex polygonal terrain turbine farm is optimized for maximal power output. This discrete, image - based calculation is particularly convenient in a circumstance in which graphics hardware and GPU processors become increasingly available and efficient, in laptop and mobile devices. This investigation opens research opportunities in mixtures of turbine types, 3D modeling of wind / terrain interaction, and accelerated calculation and visualization with GPU hardware.
  • Item
    Virtual Reality: A Literature Review and Metrics-based Classification
    (The Eurographics Association, 2018) Ankomah, Peter; Vangorp, Peter; {Tam, Gary K. L. and Vidal, Franck
    This 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
    Screen Space Particle Selection
    (The Eurographics Association, 2018) Köster, Marcel; Krüger, Antonio; {Tam, Gary K. L. and Vidal, Franck
    Analyses 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
    An Optimized Marker Layout for 3D Facial Motion Capture
    (The Eurographics Association, 2018) Will, A. D.; Martino, J. M. De; Bezerra, J.; Livesu, Marco and Pintore, Gianni and Signoroni, Alberto
    Facial motion capture (Facial Mocap) has gained increasing attention from researchers and professionals from different areas of interest, including entertainment, face-to-face communication, and training. Facial Mocap allows straightforward capture of dynamic behavior of the face from live action, providing data that can be used to drive realistic animation of a 3D virtual face. Facial Mocap is an advantageous alternative to the direct and laborious manipulation of the face model. In particular, marker-based mocap technique acquires three-dimensional facial points trajectories by tracking markers fixed on the face of an actor. However, despite the existence of several empirical facial marker layouts, the ideal positioning of the markers is still an open question. This paper presents an optimization technique to calculate the quantity and positioning facial markers and establish their influences on the polygon mesh based on the correlation of markers in a dense layout. The technique generates an optimized marker layout discarding unnecessary markers and positioning the remaining ones.
  • Item
    A Prototype of Virtual Reality System for the Visualization, Exploration and Modeling of Huge Point Clouds
    (The Eurographics Association, 2018) Ortega-Donaire, José; Segura-Sánchez, Rafael Jesús; Ogáyar-Anguita, Carlos-Javier; Rueda-Ruiz, Antonio Jesús; García-Fernández, Ignacio and Ureña, Carlos
    The use of specific techniques for the management and visualization of huge point clouds is necessary to solve the drawbacks of inefficiency derived from the size of the dataset and the techniques used to visualize it. This work presents a prototype of VR system for the visualization and management of extensive point clouds in 3D with the ability to edit specific points. For this, the tool incorporates multiresolution techniques, which improve the performance and efficiency of the system. The prototype also incorporates the management of the point cloud stored in an unstructured database; so the prototype can request parts of the dataset from the required fractions generated by an octree. This allows the progressive processing of 3D point clouds, which is very useful to control and visualize a large data set in real time.