bluuebunny/crossref_metadata_2025_split huggingface dataset:
Social relationships and friendships among young people with Down’s syndrome in secondary schools
Authors: Cuckle Pat , Wilson June 
Published: March 2003

More young people with Down’s syndrome are being taught in mainstream schools and interest in the educational aspect of inclusion has grown over the last few years.In this article Pat Cuckle, Senior Research Fellow at the University of Leeds, and June Wilson, a support teacher working for Education Leeds, explore patterns of friendship and social relationships among teenagers with Down’s syndrome. The young people who took part in the study either attend mainstream schools or resourced provision in mainstream schools. The enquiry provides fascinating insights into the participants’ views of friendship and into the range of their social experiences. Pat Cuckle and June Wilson conclude their report with a set of recommendations focusing on the need to create more opportunity for social interaction for young people with special needs.
Effective desktop videoconferencing with minimal network demands
Authors: Hearnshaw Dave 
Published: March 2003

Desktop Videoconferencing (DVC) has been shown to support effectively remote tutorials, but specific video channel requirements are not known. There is a perception that higher levels of image quality will enhance the effectiveness of the tutorial, and this has implications on scarce network bandwidth. If it can be shown that low levels of image quality are not detrimental to learning opportunities, then the use of DVC will be more attractive to institutions inhibited by fear of high network demands.Limitations in current methods for assessing video channel quality are discussed, and a new scheme for tutorial content quality analysis is outlined. The scheme has been applied to data gathered from a trial involving 30 students studying for an accredited university module. The results show that increasing the quality of the video channel resulted in no measurable increase in the quality of dialogue within the tutorials. The conclusions are that low quality images are not necessarily detrimental, and therefore DVC could be endorsed more readily where bandwidth is limited.
Managerialist Professionalism: The Destruction of a Non‐conforming Subculture
Authors: Brooks Ian 
Published: March 2003

This paper explores the complex relationship between professionalism and managerialism in the National Health Service (NHS) in the UK and argues that professional aspiration now embraces the managerial paradigm. More specifically, it describes a subculture – that of permanent night nurses – which endures a schematic difference from the now dominant day nurse culture, and is in imminent danger of extinction. It is held in contempt by many nursing professionals and managers whose agendas converge to form the unified template which informs their action. It is suggested that night nurses, marginalized and powerless, are a subculture with distinct native‐view characteristics. Ward‐based, like their day colleagues, but separated by a temporal divide, permanent night nurses recognize their difference, largely reject the new managerialist professionalism, feel unappreciated and cling to their perceived camaraderie and close patient‐relationships.This research explores the nature and origins of the new managerialist nursing profession and examines the basis of its claims of professionalism. The ethnographic methodology and research design are outlined and considerable data are presented. The paper draws upon the arguments of fellow professionals and managers who seek to deny the right of existence to this group. It is argued that ‘atrocity stories’ and other discourse, are evidence of evolving closure criteria, which exclude this apparently non‐conforming subcultural group.
A Procedural Description of Geometric Textures by Spectral and Spatial Analysis of Profiles
Authors: Dischler J.‐M. , Ghazanfarpour D. 
Published: March 2003

In this paper we describe a method for automatically generating procedural “geometric” textures, using a hybrid (spectral and spatial) analysis of profiles (ID curves). The profile describes a certain height variation for a certain abscissa. We call “geometric” textures a class of textures including “Bump” textures and “hypertextures”. In dealing with this challenge (automatic synthesis), we introduce two new key ideas.The first is to compute efficiently a compact and procedural description of the texture, by using a spectral (Fourier transform based) and spatial (histogram based) analytical approach of profiles. The resulting texture is defined as a sum of elementary random functions. This sum is generated according to the profile. The procedural description allows the direct computation of the texture values at any co‐ordinates in the Euclidean space and the stochastic aspect of the elementary functions also allows for the processing of highly random textures, with no considerable increase of computation time.The second key idea consists of using analysis in the particular and more complex case of geometric textures. For most analytical methods, underlying geometry is never considered. Using profiles as models, the resulting geometric texture is obtained by extending this profile to 2D or 3D space. The resulting texture directly matches the supplied 1D model. Hence, our method promises to be a very useful tool for easily and efficiently “modelling” any kind of geometric textures including rocks, bumps, peaks, fur, cotton and so on.
Anno 2010 – Remembering Our Future: Challenges and Frontiers of Human‐Media Technology as the Kernel for Human‐Centered Computing
Authors: Encarnação José 
Published: March 2003

Based on a forecast by Battelle, Human‐Media Technology is one of "technology’s top 10 challenges and opportunities" for the year 2010. The subject hereby is: "Humans live, science finds out how technology conforms". The goal is to develop environments that allow users to cooperate in the most efficient and natural way. Human‐centered systems will have to incorporate people as an explicit design component. This lecture will address the main goals in developing such systems based on their general characteristics and the corresponding enabling technologies: Visualization (seeing the unseen), Virtual and Augmented Reality (environment must be immersive), and also Multimedia (to introduce the combination of visual, auditory and voice data). Examples from applications and case studies will support the clarification of ideas and goals. Several videos will be used to show the impact.So far, the human‐centered interfaces to accommodate human perception and human response capabilities and limitations will have been presented and discussed. These interfaces allow to integrate the desired amount of immersion and cooperation (CSCW). Based on this, some "hands‐on" life demos will be shown to discuss the state of the art of these technologies, like Virtual Tables (responsive workbenches), special I/O technologies, etc. Some of these demos will be stand‐alone demos; others will show the potential of telecommunication for collaboration by connecting the floor with other locations to demonstrate CSCW‐based visual tele‐applications.
A Light Hierarchy for Fast Rendering of Scenes with Many Lights
Authors: Paquette Eric , Poulin Pierre , Drettakis George 
Published: March 2003

We introduce a new data structure in the form of a light hierarchy for efficiently ray‐tracing scenes with many light sources. An octree is constructed with the point light sources in a scene. Each node represents all the light sources it contains by means of a virtual light source. We determine bounds on the error committed with this approximation to shade a point, both for the cases of diffuse and specular reflections. These bounds are then used to guide a hierarchical shading algorithm. If the current level of the light hierarchy provides shading of sufficient quality, the approximation is used, thus avoiding the cost of shading for all the light sources contained below this level. Otherwise the descent into the light hierarchy continues.Our approach has been implemented for scenes without occlusion. The results show important acceleration compared to standard ray‐tracing (up to 90 times faster) and an important improvement compared to Ward’s adaptive shadow testing.
Screen‐Space Constraints for Camera Movements: the Virtual Cameraman
Authors: Jardillier Frank , Languénou Eric 
Published: March 2003

This article presents a virtual cameraman which allows us to obtain the whole set of camera movements satisfying user defined constraints specified in the image space and/or constraints on the objects of the scene. This research follows the "Declarative Modelling" approach, which focuses on a 3‐phase modeller concept: description; generation; result exploration.Our tool is based on a solver using interval arithmetic. The time dimension is treated as another variable, thus constraints can be specified for the total duration of the animation or could last only for a given amount of time. There is no keyframing and no interpolation, thereby, for the solutions obtained, the satisfaction of the specified constraints are guaranteed. Several ways to include time dimension efficiently are discussed.We claim that the method is simple enough to be implemented easily without the need of any external solver.
Conflict Neutralization on Binary Space Partitioning
Authors: James A. , Day A.M. 
Published: March 2003

The Binary Space Partitioning (BSP) tree achieves fast hidden surface removal for most practical applications where an observer can move through a scene of static objects. However, the BSP algorithm generally increases the number of polygons in a scene due to its splitting stage resulting in a detrimental effect on the priority ordering and more significantly, the display calculations (shading, lighting, shadows, etc.) of the rendering pipeline.We present the Conflict Neutralization algorithm which attempts to reduce the number of splits more effectively than existing techniques whilst maintaining the ‘standard’ model of a BSP tree. Our idea is similar to Conflict Minimization proposed by Fuchs; the significant difference is that our algorithm recognizes that a polygon suitable for selection in the Minimization criterion may subsequently stop the remainder of polygons achieving some reductions in cuts—with Conflict Neutralization, such a polygon is demoted.We compare the results of Conflict Neutralization against Conflict Minimization, the Least‐crossed with Most‐crossed tie‐breaking criterion and our own, enhanced implementation of Conflict Minimization. We show how these techniques fall into different ‘depths of analysis’.
Automatic Creation of Object Hierarchies for Radiosity Clustering
Authors: Müller Gordon , Schäfer Stephan , Fellner Dieter 
Published: March 2003

Using object clusters for hierarchical radiosity greatly improves the efficiency and thus usability of radiosity computations. By eliminating the quadratic starting phase very large scenes containing about 100k polygons can be handled efficiently. Although the main algorithm extends rather easily to using object clusters, the creation of ‘good’ object hierarchies is a difficult task both in terms of construction time and in the way how surfaces or objects are grouped to clusters. The quality of an object hierarchy for clustering depends on its ability to accurately simulate the hierarchy of the energy flow in a given scene. Additionally it should support visibility computations by providing efficient ray acceleration techniques.In this paper we will present a new approach of building hierarchies of object clusters. Our hybrid structuring algorithm provides accuracy and speed by combining a highly optimized bounding volume hierarchy together with uniform spatial subdivisions for nodes with regular object densities. The algorithm works without user intervention and is well suited for a wide variety of scenes. First results of using these hierarchies in a radiosity clustering environment are very promising and will be presented here.The combination of very deep hierarchies (we use a binary tree) together with an efficient ray acceleration structure shifts the computational effort away from form factor and visibility calculation towards accurately propagating the energy through the hierarchy. We will show how an efficient single pass gathering can be used to minimize traversal costs.
Ray Tracing and Graphics Standards
Authors: Urban B. , Haberstroh T. 
Published: March 2003

AbstractExisting standards for three‐dimensional graphic representations are unable to produce any realistically shaded images (except PHIGS PLUS, which provides discrete shading only). Ray Tracing or Radiosity are not taken into account up to this time.This article is intended to show one way to integrate the Ray Tracing technique into the pipeline of the graphics standards GKS‐3D and PHIGS. No modifications of the viewing concepts are required by our implementation.
Pandora: An Experiment in Distributed Multimedia
Authors: King Tony 
Published: March 2003

AbstractAn experimental workstation is described which supports digital video and audio in a distributed environment, and which presents this functionality to the user through the medium of a video‐extended implementation of the X Window System. The Pandora Workstation is built out of two quite separate parts. A standard UNIX machine (the Pandora Host) brings standard hardware and software computing resources to the system; a highly‐specialised processing engine (Pandora's Box) handles the high‐bandwidth, time‐critical, and device‐dependent processing. A 50 Mbit/second ATM network provides for real‐time data communication within the system. Nineteen Pandora Workstations have been deployed within Olivetti Research Ltd and the Cambridge University Computer Laboratory, and are used routinely to run distributed applications including video mail, video conferencing, and real‐time media delivery services.
A Unified Approach for Physical and Geometric Modeling for Graphics and Animation
Authors: Essa Irfan A. , Sclaroff Stan , Pentland Alex 
Published: March 2003

AbstractWe present a unified approach for geometric and physical modeling using implicit functions, for application to graphics and animation. This method extends previously proposed techniques, and allows the standard finite element method to be directly combined with geometric modeling, resulting in quick calculation of an object's mass and stiffness matrices, and its vibration modes and frequencies. Because the approach is based on an implicitfunction representation, it allows very fast collision detection and characterization. Examples of complex physical and geometric modeling are presented.
The Input Model of Standard Graphics Systems Revisited by Formal Specification
Authors: Faconti Giorgio P. , Zani Nicola , Paterno' Fabio 
Published: March 2003

AbstractThis paper describes the specification of an input model for graphics systems. The initial aim of the work reported in this paper was to revise the input model adopted by graphics standards by means of formal specification techniques in order to acquire a deep knowledge of its capabilities, to eventually discover errors and to develop improvements. Taking into account similar works done in this area by others and considering a number of major issues related to input recently discussed within the graphics community, a new model is being proposed that addresses the very key concepts of parallelism, extensibility and reconfigurability. The model is based upon composition operations defined over basic components specified as a set of concurrent processes. Composition operations and process definitions have been formally specified by using the LOTOS notation and investigated by means of the LOTOS Interactive Tools Environment. In the first part of the paper, the input model of graphics standards is shortly examined in the light of the results so far achieved by related works on formal specification of computer graphics systems. Subsequently, an improved model is presented. Finally, its capability of simulating the traditional operating modes of logical input devices and a methodology for defining new operating modes is demonstrated.
Adaptive Sampling of Area Light Sources in Ray Tracing Including Diffuse Interreflection
Authors: Kok Arjan J. F. , Jansen Frederik W. 
Published: March 2003

AbstractRay tracing algorithms that sample both the light received directly from light sources and the light received indirectly by diffuse reflection from other patches, can accurately render the global illumination in a scene and can display complex scenes with accurate shadowing. A drawback of these algorithms, however, is the high cost for sampling the direct light which is done by shadow ray testing. Although several strategies are available to reduce the number of shadow rays, still a large number of rays will be needed, in particular to sample large area light sources. An adaptive sampling strategy is proposed that reduces the number of shadow rays by using statistical information from the sampling process and by applying information from a radiosity preprocessing. A further reduction in shadow rays is obtained by applying shadow pattern coherence, i.e. reusing the adaptive sampling pattern for neighboring sampling points.
Fractals and Solid Modeling
Authors: Gröller Eduard 
Published: March 2003

AbstractTrying to combine fractal geometry and solid modeling seems to be a contradiction in itself, In this paper a new type of 3D objects is presented that accomplishes this combination in a specific way. Objects with a fractal macro structure and a 3D solid micro structure can be specified and rendered efficiently by using context free, attribute, geometric grammars. This new object type can be incorporated into the CSG‐modeling technique (Constructive Solid Geometry) in two ways: a) using CSG for the specification of the micro structure of the new object type, b) using these fractal like objects as a new type of primitive in the CSG model. Ray tracing is used for generating high quality images of these geometrically complex objects.
Performance of Space Subdivision Techniques in Ray Tracing
Authors: McNeill M. D. J. , Shah B. C. , Hebert M.‐P. , Lister P. F. , Grimsdale R. L. 
Published: March 2003

AbstractWhilst providing images of excellent quality, ray tracing is a computationally intensive task. The first part of this paper compares the speed‐up achieved in ray tracing using various space subdivision algorithms and discusses the implications of implementing the algorithms on parallel processing systems. The second part addresses the problem of building the data structure within the rendering process, a situation which occurs when the rendering process is parallelised and dynamic scenes are rendered. Greater performance can be achieved with dynamic structure building compared to creation of the structure prior to rendering. The dynamic building algorithm proposed reduces the building time and storage cost of space subdivision structures, and decreases the data structure creation‐render cycle time, thus enhancing image parallelism performance.
Modelling and Programming Evolutions of Surfaces
Authors: Chen X. , Lienhardt P. 
Published: March 2003

AbstractIn recent years, a lot of work has been done on modelling natural phenomena and simulating the evolution of natural objects. For instance, procedural methods have been developed for simulating corpuscular phenomena and tree growth. In this paper we present a new procedural method for simulating evolutions of subdivisions of surfaces (i.e. partitions of surfaces into vertices, edges and faces). The representations of topology, embedding and photometry are clearly distinguished in the geometric model used for the representation of such subdivisions and thus, each of these features may be evolved independently (as in natural metamorphoses). Evolutions are achieved by applying topological and embedding operations on the geometric model. Control of these evolutions is based upon the behaviour concept. Behaviours (i.e. sets of operations) are associated with cells of the modelled subdivision. At each step, and for each cell, the corresponding behaviour is applied to the cell. The definition and computation of parameters have been studied, in order to control such evolutions. The method has been implemented and tested with many examples of surface evolutions (mainly evolutions of vegetal surfaces: leaves, flowers). Based on the method, a language has been defined for programming surface evolutions.
The Potential Equation and Importance in Illumination Computations
Authors: Pattanaik S. N. , Mudur S. P. 
Published: March 2003

AbstractAn equation adjoint to the luminance equation for describing the global illumination can be formulated using the notion of a surface potential to illuminate the region of interest. This adjoint equation which we shall call as the potential equation, is fundamental to the adjoint radiosity equation used to devise the importance driven radiosity algorithm. In this paper we first briefly derive the adjoint system of integral equations and then show that the adjoint linear equations used in the above algorithm are basically discrete formulations of the same. We also show that the importance entity of the linear equations is basically the potential function integrated over a patch. Further we prove that the linear operators in the two equations are indeed transposes of each other.
The Cone of Normals Technique for Fast Processing of Curved Patches
Authors: Shirmun Leon A. , Abi‐Ezzi Salim S. 
Published: March 2003

AbstractThe cone of normals technique for curved surface patches allows to perform various quick tests at the patch level such as front‐ or backfacing test, light influence test, and existence of silhouette edges test. For a given patch, a truncated cone of normals is constructed at creation time, which contains all points and all normal directions of the patch. At traversal time, a simple scalar product test determines whether the whole patch is backfacing or frontfacing, so that the costly step of tessellating the patch is avoided in case of patch level face culling. In addition, the technique quickly determines which light sources have no influence on a patch, and which patches have no silhouette edges. The technique can also be used for other surface primitives, such as triangular strips and quadrilateral meshes,
Classification of Ray‐Generators in Uniform Subdivisions and Octrees for Ray Tracing
Authors: Endl Robert , Sommer Manfred 
Published: March 2003

AbstractSpatial subdivisions cause an enormous acceleration of ray tracing due to the reduction of ray‐object intersections. For this purpose it is necessary to generate the sequence of ray‐cells (all cells met consecutively by a given ray). A method generating this sequence will be called a ray‐generator. First this paper analyses the common properties of ray‐generators in order to establish a classification. Then some well‐known ray‐ generators are described and classified, as well as some new ones. In the sequel nine different ray‐generators are implemented in one single program allowing direct comparisons with the same scene. Finally, global time measurements for two scenes are given, as well as time measurements for random rays enabling the calculation of mean values for the time of initialization and determination of ray‐cells.
A Survey of Shading and Reflectance Models
Authors: Schlick Christophe 
Published: March 2003

AbstractSince the beginning of computer graphics, three decades ago, a large number of models intended to describe the behaviour of light on a given point of a surface have been proposed. Almost every author uses his own terminology and/or notation. To understand clearly the similarities and the differences between existing models, reformulating them with a unified notation is essential. This has been done by Hall in 1986. This paper is a new survey of shading and reflectance models, including the most recent models. Moreover, after the lengthy enumeration, some original models are proposed, which attempt to include interesting features of previous disjointed work into new formulations.