Search Results

Now showing 1 - 5 of 5
  • Item
    Real-Time Simulation of a Stretcher Evacuation in a Large-Scale Virtual Environment
    (Blackwell Publishers Ltd and the Eurographics Association, 2000) Hubbold, Roger; Keates, Martin
    This paper presents a case study of navigation and manipulation in a large, geometrically complex, virtual environment representing an off-shore gas platform. Our approach is based on a combined force-field navigation and collision detection algorithm. After describing the basic algorithm, we extend and apply it to a real-time simulation of two avatars carrying a third avatar on a stretcher. The extensions include a probing technique, using a virtual foot and simulated gravity, to permit ascending and descending stairs and ladders. A set of constraints between the stretcher and avatars enforces realistic lifting positions. The simulation is controlled interactively with a hand-held 3D mouse. The force fields assist the user in manoeuvring through tight spaces, while collision detection guarantees that neither the stretcher nor the avatars can pass through obstructions, such as pipe-work or hand-rails. Results are presented for a case study of a complete simulation running on a PC with a moderately fast 3D graphics card. These demonstrate that the method delivers a useful frame rate for the off-shore gas platform.
  • Item
    12th Eurographics Symposium on Virtual Environments
    (The Eurographics Association and Blackwell Publishing Ltd, 2007) Hubbold, Roger; Jorge, Joaquim; Lin, Ming
  • Item
    Rapid Shadow Generation in Real-World Lighting Environments
    (The Eurographics Association, 2003) Gibson, Simon; Cook, Jon; Howard, Toby; Hubbold, Roger; Philip Dutre and Frank Suykens and Per H. Christensen and Daniel Cohen-Or
    We propose a new algorithm that uses consumer-level graphics hardware to render shadows cast by synthetic objects and a real lighting environment. This has immediate benefit for interactive Augmented Reality applications, where synthetic objects must be accurately merged with real images. We show how soft shadows cast by direct and indirect illumination sources may be generated and composited into a background image at interactive rates. We describe how the sources of light (and hence shadow) affecting each point in an image can be efficiently encoded using a hierarchical shaft-based subdivision of line-space. This subdivision is then used to determine the sources of light that are occluded by synthetic objects, and we show how the contributions from these sources may be removed from a background image using facilities available on modern graphics hardware. A trade-off may be made at runtime between shadow accuracy and rendering cost, converging towards a result that is subjectively similar to that obtained using ray-tracing based differential rendering algorithms. Examples of the proposed technique are given for a variety of different lighting environments, and the visual fidelity of images generated by our algorithm is compared to both real photographs and synthetic images generated using non-real-time techniques.
  • Item
    MAVERIK: A Virtual Reality System for Research and Teaching
    (The Eurographics Association, 2023) Howard, Toby; Hubbold, Roger; Murta, Alan; José Carlos Teixeira; Werner Hansmann; Michael B. McGrath
    This paper describes some experiences with the use of the MAVERIK system for supporting undergraduate and postgraduate teaching and research. MAVERIK is a high-level system for creating and managing interactive virtual environments. lt is available free under the GNU General Public Licence. MAVERIK is modular and extensible, and its use of Mesa, the free OpenGL-like graphics system, means that it can be run on low- cost PCs, making it especially suitable for use in computer graphics and visualization education. We discuss the novel architecture and main features of MAVERIK, and illustrate its use by presenting case studies of projects udertaken by our students.
  • Item
    Flexible Image-Based Photometric Reconstruction using Virtual Light Sources
    (Blackwell Publishers Ltd and the Eurographics Association, 2001) Gibson, Simon; Howard, Toby; Hubbold, Roger
    Photometric reconstruction is the process of estimating the illumination and surface reflectance properties of an environment, given a geometric model of the scene and a set of photographs of its surfaces. For mixed-reality applications, such data is required if synthetic objects are to be correctly illuminated or if synthetic light sources are to be used to re-light the scene. Current methods of estimating such data are limited in the practical situations in which they can be applied, due to the fact that the geometric and radiometric models of the scene which are provided by the user must be complete, and that the position (and in some cases, intensity) of the light sources must also be specified a-priori. In this paper, a novel algorithm is presented which overcomes these constraints, and allows photometric data to be reconstructed in less restricted situations. This is achieved through the use of virtual light sources which mimic the effect of direct illumination from unknown luminaires, and indirect illumination reflected off unknown geometry. The intensity of these virtual light sources and the surface material properties are estimated using an iterative algorithm which attempts to match calculated radiance values to those observed in photographs. Results are presented for both synthetic and real scenes that show the quality of the reconstructed data and its use in off-line mixed-reality applications.