Volume 16 (1997)
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Item A Framework for Interacting with Paper(Blackwell Publishers Ltd and the Eurographics Association, 1997) Robinson, Peter; Sheppard, Dan; Watts, Richard; Harding, Robert; Lay, SteveThis paper reports on ways of using digitised video from television cameras in user interfaces for computer systems. The DigitalDesk is built around an ordinary physical desk and can be used as such, but it has extra capabilities. A video camera mounted above the desk, pointing down at the work surface, is used to detect where the user is pointing and to read documents that are placed on the desk. A computer-driven projector is also mounted above the desk, allowing the system to project electronic objects onto the work surface and onto real paper documents. The animated paper documents project is considering particular applications of the technology in electronic publishing. The goal is to combine electronic and printed documents to give a richer presentation than that afforded by either separate medium.This paper describes the framework that has been developed to assist with the preparation and presentation of these mixed-media documents. The central component is a registry that associates physical locations on pieces of paper with actions. This is surrounded by a number of adaptors that assist with the creation of new documents either from scratch or by translating from conventional hypermedia, and also allow the documents to be edited. Finally the DigitalDesk itself identifies pieces of paper and animates them with the actions described in the registry.Item EG Network Service(Blackwell Publishers Ltd and the Eurographics Association, 1997)Item Interactive Visualization of Implicit Surfaces with Singularities(Blackwell Publishers Ltd and the Eurographics Association, 1997) Rosch, Angela; Ruhl, Matthias; Saupe, DietmarThis paper presents work on two methods for interactive visualization of implicit surfaces: physically-based sampling using particle systems and polygonization followed by physically-based mesh improvement which explicitly makes use of the surface-defining equation. While most previous work applied to bounded manifolds without singularities and without boundary (topological spheres) we broaden the scope of the methods to include surfaces with such features, in particular cusp points and surface self-intersections. These aspects are not (yet) essential for computer graphics modelling with implicit surfaces but they naturally occur in simulations of interest in mathematical visualization. In this paper we use the Kummer family of algebraic surfaces as an example.Item Impressions of SIGGRAPH '97: Los Angeles, August 3rd-8th 1997(Blackwell Publishers Ltd and the Eurographics Association, 1997)Item Calendar of Events(Blackwell Publishers Ltd and the Eurographics Association, 1997) Greiner, GuntherItem A Muscle-based Feed-forward Controller of the Human Body(Blackwell Publishers Ltd and the Eurographics Association, 1997) Komura, Taku; Shinagawa, Yoshihisa; Kunii, Tosiyasu L.There is an increasing demand for human body motion data. Motion capture and physical animation have been used to generate such data. It is, however, apparent that such methods cannot automatically generate arbitrary human body motions. A human body is a redundant multi-linked body controlled by a number of muscles. For this reason, the muscles must work appropriately and cooperatively for controlling the whole body. It is well-known that the human body control system is composed of two parts: The open-loop feed-forward control system and the closed-loop feedback control system. Many researchers have investigated the characteristics of the latter by analyzing the response of a human body to various external perturbations. However, for the former, very few studies have been done. This paper proposes an open-loop feed-forward model of the lower extremities which includes postural control for accurate animation of a human body. Assumptions are made here that the feed-forward controller minimizes a certain objective value while keeping the balance of the body stable. The actual human motion data obtained using a motion capturing technique is compared with the trajectory calculated using our method for verification. The best criteria which is based on muscle dynamics is proposed. Using our method, dynamically correct human animation can be created by merely specifying a few key postures.Item Surface Reconstruction Using Alpha Shapes(Blackwell Publishers Ltd and the Eurographics Association, 1997) Guo, Baining; Menon, Jai; Willette, BrianWe describe a method for reconstructing an unknown surface from a set of data points. The basic approach is to extract the surface as a polygon mesh from an ?-shape. Even though alpha shapes are generalized polytopes having complicated internal structures, we show that manifold surfaces, with or without boundaries, can be efficiently generated, and these surfaces completely describe the ?-shapes to the extent that they are visible from outside. Unlike the original ?-shapes, the polygonal surfaces can be easily simplified to yield compact models suitable for a variety of geometric modeling applications such as surface fitting.Item Bulge Elimination in Convolution Surfaces(Blackwell Publishers Ltd and the Eurographics Association, 1997) Bloomenthal, JulesThe relationship between surface bulge and several implicit blend techniques, particularly those based on convolution of a skeleton, is discussed. An examination of branching skeletons reveals that for two and three-dimensional skeletons, the surface will be bulge-free if skeletal elements are sufficiently large with respect to the convolution kernel.Item Animation by Deformation of Space-Time Objects(Blackwell Publishers Ltd and the Eurographics Association, 1997) Aubert, Fabrice; Bechmann, DominiqueThis article presents the properties of animation with space-time objects. A space-time object means here a geometrical object embedded in R4 with a volumic topology. Resulting animations are obtained by deforming space-time objects with a free-form deformation model. In this way topological modifications, such as disconnecting or hole making, as well as classical geometrical modifications, can be created in an animated object.Item Virtually Documented Environments: A New Interface Paradigm for Task-oriented Access to Information(Blackwell Publishers Ltd and the Eurographics Association, 1997) Kakez, Samory; Conan, Vania; Bisson, PascalWe present a suitable virtually documented environment system providing the user with high level interaction possibilities. The system is dedicated to applications where the operator needs to have his hands free in order to access information, carry out measurements and/or operate on a device (e.g. maintenance, instruction). The system merges video images acquired through a head-mounted video camera with synthetic data (multimedia documents including CAD models and text) and presents these merged images to the operator. Registration techniques allow the operator to visualise information properly correlated to the real world: this is an essential aspect in order to achieve a feeling of presence in a real environment.We increase the sense of immersion through high level Human-Computer Interaction (HCI) allowing hands-free access to information through vocal commands as well as multimodal interaction associating speech and gesture. In this way, the user can access information and manipulate it in a very natural manner. We discuss the construction of the documentation system and the requested functionalities which led to the system architecture.Item Computing Volumes of Solids Enclosed by Recursive Subdivision Surfaces(Blackwell Publishers Ltd and the Eurographics Association, 1997) Peters, Jorg; Nasri, AhmadThe volume of a solid enclosed by a recursive subdivision surface can be approximated based on the closed-form representation of regular parts of the subdivision surface and a tight estimate of the local convex hull near extraordinary points. The approach presented is efficient, i.e. non-exponential, and robust in that it yields rapidly contracting error bounding boxes. An extension to measuring higher-order moments is sketched.Item An Efficient Code-Based Voxel-Traversing Algorithm(Blackwell Publishers Ltd and the Eurographics Association, 1997) Zalik, Borut; Clapworthy, Gordon; Oblonsek, CrtomirItem Book Reviews(Blackwell Publishers Ltd and the Eurographics Association, 1997) Howard, TobyItem Eurographics'98(Blackwell Publishers Ltd and the Eurographics Association, 1997)Item Eurographics UK Chapter 16th Annual General Meeting: University of East Anglia, Norwich, March 25, 1997(Blackwell Publishers Ltd and the Eurographics Association, 1997)Item Prize Competition: 1998 Cover Photograph(Blackwell Publishers Ltd and the Eurographics Association, 1997)Item Preface and Table of Contents (EG 1997, CGF 16-3)(Blackwell Publishers Ltd and the Eurographics Association, 1997) Fellner, Dieter W.; Szirmay-Kalos, László-Item Parallel Progressive Ray-tracing(Blackwell Publishers Ltd and the Eurographics Association, 1997) Notkin, Irena; Gotsman, CraigA dynamic task allocation algorithm for ray-tracing by progressive refinement on a distributed-memory parallel computer is described. Parallelization of progressive ray-tracing is difficult because of the inherent sequential nature of the sample location generation process, which is optimized (and different) for any given image. We report on experimental results obtained from our implementation of this algorithm on a Meiko parallel computer. The three performance measures of the algorithm, namely, load-balance, speedup, and image quality, are shown to be good.Item EG Eurographics ' 97: Annual Conference of the European Association for Computer Graphics(Blackwell Publishers Ltd and the Eurographics Association, 1997)Item Eurographics '97 Awards(Blackwell Publishers Ltd and the Eurographics Association, 1997)