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Item Watch Out - There s a New Logo About!(Blackwell Publishing Ltd and the Eurographics Association, 1989) Hubbold, RogerItem Real-Time Simulation of a Stretcher Evacuation in a Large-Scale Virtual Environment(Blackwell Publishers Ltd and the Eurographics Association, 2000) Hubbold, Roger; Keates, MartinThis 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, MingItem Flexible Image-Based Photometric Reconstruction using Virtual Light Sources(Blackwell Publishers Ltd and the Eurographics Association, 2001) Gibson, Simon; Howard, Toby; Hubbold, RogerPhotometric 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.Item From The Chairman(Blackwell Publishing Ltd and the Eurographics Association, 1989) Hubbold, Roger