bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Priority Face Determination Tree for Hidden Surface Removal
Authors: James A. , Day A. M. 
Published: March 2003

Many virtual environments are built from a set of polygons that form the basis of objects in the scene. Using priority‐list algorithms, the sequence in which these polygons are drawn is dependent upon the location of an observer; the polygons must be ordered correctly before a realistic image can be displayed. It is necessary for a scene to be drawn correctly in real time from all locations before the observer can move interactively around the scene with complete freedom.The binary‐space partitioning (BSP) tree developed by Fuchs, Kedem and Naylor in 1980 stores the view independent priority of a set of polygons which can be used to obtain the correct order for any given view‐point. However, the number of polygons grows significantly due to the BSP splitting stage, increasing the number of nodes in the tree. This affects linearly the number of tests necessary to traverse the tree to obtain the priority of the set of polygons.The algorithm presented here is built using its associated BSP tree, but attempts to reduce the number of tests to, log4/3n, at the cost of a tree of size of O(N1.5log4/3n−1), where n is the initial number of polygons in the scene, and N the resulting number after BSP splitting. To achieve the increase in run‐time efficiency, a height plane is used to restrict the view point of the observer to a fixed height, but the key to the efficiency of the algorithm is in the use of polygonal dependencies. In the scene; if we know our location relative to the front or back of a polygon, then our position relative to one‐quarter of the remaining polygons, in the expected worst‐case, can be determined.
Subdivision Schemes for Thin Plate Splines
Authors: Weimer Henrik , Warren Joe 
Published: March 2003

Thin plate splines are a well known entity of geometric design. They are defined as the minimizer of a variational problem whose differential operators approximate a simple notion of bending energy. Therefore, thin plate splines approximate surfaces with minimal bending energy and they are widely considered as the standard "fair" surface model. Such surfaces are desired for many modeling and design applications.Traditionally, the way to construct such surfaces is to solve the associated variational problem using finite elements or by using analytic solutions based on radial basis functions. This paper presents a novel approach for defining and computing thin plate splines using subdivision methods. We present two methods for the construction of thin plate splines based on subdivision: A globally supported subdivision scheme which exactly minimizes the energy functional as well as a family of strictly local subdivision schemes which only utilize a small, finite number of distinct subdivision rules and approximately solve the variational problem. A tradeoff between the accuracy of the approximation and the locality of the subdivision scheme is used to pick a particular member of this family of subdivision schemes.Later, we show applications of these approximating subdivision schemes to scattered data interpolation and the design of fair surfaces. In particular we suggest an efficient methodology for finding control points for the local subdivision scheme that will lead to an interpolating limit surface and demonstrate how the schemes can be used for the effective and efficient design of fair surfaces.
Stochastic Motion—Motion Under the Influence of Wind
Authors: Shinya Mikio , Fournier Alain 
Published: March 2003

AbstractStochastic approaches are very effective for modelling natural phenomena. This paper presents a motion model based on a stochastic process as well as physics, and proposes motion synthesis techniques for stochastic motion—motion under the influence of wind.The motion synthesis process is modelled by a cascade system of three components: wind model, dynamic model, and deformation model. Wind models produce spatio‐temporal wind velocity fields using the power spectrum and auto‐correlation of wind, just like fractal geometry. Dynamic models describe the dynamic response of the systems, using equation systems or response functions. Deformation models produce deformed shapes of objects according to the geometric models of the objects and the results of the dynamic systems.The biggest advantage of the model is its generality and consistency. The model is applicable to most of the existing trees and grass models, including structural models, particle systems, impressionist models, and 3D texture. It is demonstrated that the coupling of stochastic approaches and physically‐based approaches can synthesize realistic motion of trees, grass and snow with modest computational cost.
Modelling the Texture of Paint
Authors: Cockshott Tunde , Patterson John , England David 
Published: March 2003

AbstractWe present an extension to the WET & STICKY model. A method of modelling textured and shiny paint is described using bump mapping and standard illumination models. The qualities of the paint are used to supply input to the texture and lighting models. We demonstrate that a dynamic model of textured paint provides the user with valuable visual cluesfor the production of realistic painted images. We also propose further extensions which would allow the use of different lighting models for different paints, allowing for paint attributes which are unachievable either with traditional painting or with earlier forms of electronic painting.
Two‐manifold cell‐decomposition of r‐sets.
Authors: Falcidieno Bianca , Ratto Ornella 
Published: March 2003

AbstractThis paper discusses the relationships studied between manifold solids and r‐sets by defining an r‐set as a decomposition in two‐manifold cells. This decomposition is represented as a graph (Two‐manifold Cell Decomposition graph TCD) in which each node corresponds to a 2 manifold component of the regular set, while each arc or hyperarc defines a non‐manifold adjacency between components. The TCD model and data structure encoding it were designed in order to be compatible with a traditional boundary architecture.
3D Computational Morphology
Authors: Veltkamp Remco C. 
Published: March 2003

AbstractComputational Morphology is the analysis of form by computational means. This discipline typically uses techniques from Computational Geometry and Computer Aided Geometric Design. The present paper is more specifically about the construction and manipulation of closed object boundaries through a set of scattered points in 3D. Original results are developed in three stages of computational morphology:

impose a geometrical structure on the set of points;
construct a polyhedral boundary surface from this geometrical structure;
build a hierarchy of polyhedral approximations together with localization information;

The economic advantage of this approach is that there is no dependency on any specific data source. It can be used for various types of data sources or when the source is unknown.
On the Application of Quantization and Dithering Techniques to History of Arts
Authors: Coltelli P. , Faconti G. , Marfori F. 
Published: March 2003

AbstractThe diffusion of computing techniques within humane studies is considerably increasing, due to technological advances and reduction in computing costs, with History of Arts being one of the most interesting fields of application. In fact, several domains related to works of arts might be investigated other than archival and retrieval of information: this includes the planning for the preservation and restoration, the developing of critical examinations of artworks as well as the supporting of less specialized activities such as teaching, presentation of museum exhibitions and spreading of information.Within this framework, it is of particular interest to review already known image compression techniques from other fields and to evaluate their applicability taking into account the peculiarities and the requirements of this specific domain. A distinguishing aspect of History of Arts is the requirement to keep the maximum approximation of the original information on each point of an image. This peculiarity strongly requires that the set of pixels of the same color in the original image is bound to a unique color in the final image and that each color in the final image uniquely determines the set of colors it represents. This requirement constrains the applicability in this domain to those quantization algorithms satisfying this property while still minimizing the quantization error.The paper gives a formal definition of the above requirement and justifies the use of the quantization and dithering algorithms based on the octree reduction technique. Following, the results given by the application of these techniques to several paintings are shown. Finally, the measured quantization errors are compared with those obtained by applying the median‐cut algorithm.
Nonsplitting Macro Patches for Implicit Cubic Spline Surfaces
Authors: Guo B. 
Published: March 2003

AbstractMacro patches are important for generating quadric or cubic implicit spline surfaces from the input of a polyhedron. All existing macro patches split the triangular facets of the polyhedron; this paper presents cubic nonsplitting macro patches (NMP) that do not split these facets. The NMP's are based on a necessary and sufficient condition for nonsplitting constructions of implicit cubic spline surfaces. This condition can be satisfied for most practical applications, so the NMP's lead to an efficient and powerful spline surface scheme using implicit cubics. The free parameters in an NMP are set using a new technique for excluding topological anomalies such as extraneous sheets, splits, unwanted holes, self‐intersections, and unwanted handles. Each cubic patch obtained by this technique best approximates, in a least‐squares sense, a quadric patch from a single algebraic component of a monotone polynomial derived from the input data.
Designing and Implementing a Grid‐Distortion Mapping Based on Variational Principles
Authors: Arad Nur 
Published: March 2003

AbstractA grid‐distortion mapping based on variational principles is described. The mapping is first defined between any two equivalent regular grids with minor geometric restrictions, and is then optimally extended to the interior of the source grid in a sense to be defined. The result is independent of the particular representation of the curves, and depends only on geometric properties of the grids. We then proceed to construct an approximation to the mapping defined and demonstrate its implementation. Finally, this algorithm is compared to several competing ones, in particular separable (scanline) algorithms.
Surface Reconstruction from Unstructured 3D Data
Authors: Algorri Maria‐Elena , Schmitt Francis 
Published: March 2003

AbstractBuilding 3 0 models from unstructured data is a problem that arises increasingly as new 30 scanning technology is able to produce large and complex databases of full 3 0 information. Huge efforts put into segmenting entire sets of 20 images demand robust tools that are then able to reconstruct any arbitrary 30 surface segmented from the images. In this paper we propose an algorithmic methodology that automatically produces a surface from a set of points in ℜ3 about which we have no topological knowledge. Our method uses a spatial decomposition and a surface tracking algorithm to produce a rough approximation S' of the unknown manifold S. The produced surface S' serves as a robust initialisation for a physically based modeling technique that yields the fine details of S and so improves the quality of the reconstruction.
Generation of Smooth Surfaces by Controlling Curvature Variation
Authors: Higashi Masatake , Tsutamori Hideo , Hosaka Mamoru 
Published: March 2003

AbstractTo satisfy a designer's intention for constructing aesthetic shapes such as automotive bodies, we propose a surface generation method. In the surface design process, designers determine shapes according to their great concern for the reflected images of vehicle surroundings, shade lines and highlight lines. Since reflection and shading are affected by changes of surface normal, the curvature variation of the surface, which represents the change of the surface normal, should be smooth and distributed as designers want. The proposed method controls curvature distribution directly by determining a surface shape from an evolute, which is a locus of the curvature center of the generatrix and moves along directrices to form the surface. It first generates evolutes of boundary curves to be generatrices as rational Bezier curves, then interpolates their shapes with the Bezier polygons, and locates the interpolated shape to the corresponding position of the directrices. By applying this method, we have confirmed that a smooth shape is generated from four boundary curves.
The Politics of Corporate Control and the Future of Shareholder Activism in the United States
Authors: Thompson Tracy A. , Davis Gerald F. 
Published: March 2003

Over the past eleven years, activists – particularly public pension funds such as the California Employees Retirement System (CalPERS) – are credited with prompting boards to roust underperforming management at some of the largest US corporations, and they have pushed for reforms in areas ranging from compensation to corporate strategy. Evidence for shareholders’ increased interest in corporate governance is clear. In the 1984–5 proxy season, shareholder resolutions totaled 275, and the average vote was 5.74%; by 1991–2, resolutions and the average vote on them had climbed to 487 and 24.06%, respectively. In 1992, shareholders were also successful in pushing through regulatory changes that gave them the right to communicate with each other outside the management–dominated proxy system.After 11 years of shareholder activism, where does the movement stand today? Understanding the development of the shareholder–rights movement, the prospects for governance reform, and the future evolution of the movement requires a sophisticated understanding of how the politics of corporate control is accomplished and, in particular, the important role that social structure plays. In this article, we suggest that social movement theory, which sociologists have used to explain collective action by groups ranging from the Civil Rights movement to Mothers Against Drunk Driving, provides a useful tool for analysing owner–management conflicts, and in particular, the recent rise of the shareholder–rights movement in the United States. After briefly discussing the traditional economic view of corporate governance and its shortcomings, we argue that more–or–less organized politics is an essential ingredient of the American system of corporate governance. We then present a social movement framework to explain the rise in investor activism. We conclude by continuing our application of this framework to examine the maturation of this movement and to assess its future, in part by comparing it to other contemporary, confrontational movements.
Developments in Corporate Governance in Central and Eastern Europe
Authors: Mallin Chris 
Published: March 2003

The countries of western Europe have seen far reaching corporate governance developments in recent years, ranging from the Cadbury Report in the UK to the Vienot Report in France. These developments have been discussed in toto in the report of the CEPS working party on corporate governance in Europe. However alongside the developments in western Europe, there are fundamental political and economic changes going on in the countries in Eastern and Central Europe (CEEC) which have significant implications for the development of corporate governance in these countries.In this paper we analyse the changes that have taken place in a number of CEEC countries, highlighting both the commonalities and the differences, and the way that these countries are developing in terms of their corporate governance structures. The demise of central planning, for example, has led to a shift of control, and we seek to examine such issues as where control now lies, the effects of privatisation, and the problems of development of institutional arrangements for corporate governance.Financial institutions have a key role to play in the changes in the CEEC and therefore the latter part of the paper places a special emphasis on the role of financial institutions, particularly banks, as monitors in the CEEC, and analyses the banks’ role in firms’ restructuring. The implications for the role of banks in any developing corporate governance system are immense, with banks playing a central role as monitors of corporate success. However the privatisation of banks and firms is not, per se, sufficient to ensure that these enterprises develop adequate corporate governance structures which are able to cope with problems endemic in the current framework, and are capable of evolving to take account of future changes.We examine the existing structures in several CEEC, and provide a taxonomy of changes that have occurred to date. We discuss likely future changes and conclude on the likely effects on corporate governance in the CEEC.
Review article: Parents and Children in the Early Middle Ages
Authors: Stafford Pauline 
Published: March 2003

Books reviewed in this article:Katrien Heene, The Legacy of Paradise. Marriage, Motherhood and Women in Carolingian Edifying LiteratureMarcelle Thiébaux (ed), Dhuoda, Handbook for her Warrior Son. Liber ManualisSally Crawford, Childhood in Anglo‐Saxon England
Education for the masses? The interaction between wealth, educational and political inequalities
Authors: Ferreira Francisco H.G. 
Published: March 2003

This paper presents a simple model of distribution dynamics, in which the distributions of wealth, education and political power are circularly endogenous. Different levels of education translate into different income and wealth levels. Political power may (or may not) vary with wealth, and in turn affects decisions on the level of public expenditure on education. Since the market for education credit is imperfect, some people might need to rely on public schooling, the quality of which depends on those expenditure levels. As a result, educational opportunities differ along the wealth distribution. The dynamic system displays multiple equilibria, some of which are characterized by a vicious circle of interaction between educational, wealth and political inequalities. These particular equilibria, which are more unequal, are also shown to be inefficient in terms of aggregate output levels. Switching equilibria may be achieved through redistribution of political power.JEL classification: D31, D63.
The EU attitude to unilateral euroization: Misunderstandings, real concerns and sub‐optimal admission criteria
Authors: Bratkowski Andrzej , Rostowski Jacek 
Published: March 2003

European Union objections to unilateral euroization by applicant countries are categorized as either a misunderstanding of what euroization entails or as justified concern, which should be alleviated by candidates wishing to euroize. Some ways in which candidates can alleviate concerns are discussed, as well as possible adjustments to the Maastricht criteria which might better protect both sides' interests. The paper concludes that the EU would benefit if it accepted unilateral euroization by applicants.JEL classification: E42, F33, F42, P24.
Competition and ownership structure: Substitutes or complements? Evidence from the Warsaw Stock Exchange
Authors: Grosfeld Irena , Tressel Thierry 
Published: March 2003

In this paper we analyse the impact of product market competition and ownership structure on firm performance. Our results show that product market competition has a positive and significant impact on performance. Concerning the effect of ownership concentration, we find a U–shaped relationship with performance. Firms with relatively dispersed and relatively concentrated ownership have higher productivity growth than firms with an intermediate level of ownership concentration. This correlation between concentration of ownership and productivity growth is not explained by the type of the controlling shareholder. Finally, product market competition and good governance tend to reinforce each other rather than to be substitutes. Competition has no significant effect on performance for the firms with ‘poor’ governance; on the contrary, it has a significant positive effect in the case of firms with ‘good’ corporate governance.JEL classification: D24, G32, L1, P2.
Beyond Marriage and the Convent: Women, Class and Honour in Renaissance Italy
Authors: Horodowich Elizabeth 
Published: March 2003

Ann Crabb, The Strozzi of Florence: Widowhood and Family Solidarity in the RenaissanceStanley Chojnacki, Women and Men in Renaissance Venice: Twelve Essays on Patrician SocietyMonica Chojnacka, Working Women of Early Modern VeniceJoanne M. Ferraro, Marriage Wars in Late Renaissance Venice
On the Aggregate Impact of Exchange Rate Variability on EU Trade
Authors: Sekkat Khalid 
Published: March 2003

Abstract
The paper assesses the aggregate impact of exchange rate variability on EU trade. A small econometric model is constructed and estimated for five countries: France, Italy, Germany, the UK and Belgium. The results show that there exists a long-term relationship between trade variables and relative costs, demand, exchange rates and expected exchange rates. No such relation exists with respect to volatility. It is also found that while the most important determinants of trade variables are relative wages and demand, variability is also responsible for a decrease in the growth rate of these variables.
Strategic Cost Reduction and Cost Revelation
Authors: Jin Jim Y. 
Published: March 2003

Abstract
Strategic cost reduction requires cost transparency. When unilateral cost revelation is feasible, strategic cost reduction indeed arises as equilibrium. If it is not feasible, however, credible revelation has to be organized, possibly by a trade association. Then, firms face a prisoners' dilemma: in Cournot duopoly, cost revelation arises as an equilibrium, but hurts firms; in Bertrand duopoly, cost concealing is the equilibrium, while firms would be better off with cost revelation. Since cost revelation is socially desirable (undesirable) in Cournot (Bertrand) competition, it should be encouraged (discouraged).
Non-cooperative vs. Minimum- Rate Commodity Taxation
Authors: Hvidt Morten , Bo Nielsen Søren 
Published: March 2003

Abstract
This paper demonstrates, within a simple two-country model of commodity taxation and cross-border shopping, that the tax revenue (welfare) effects of a minimum tax requirement depend crucially on the character of the initial non-cooperative tax equilibrium, i.e. whether it is Nash or Stackelberg.
Macroeconomic Synchronization Between G3 Countries
Authors: Peirό Amado 
Published: March 2003

Abstract
This paper studies the existence of a world business cycle by examining quarterly and annual comovements in production, prices and interest rates in the three main world economies: Germany, Japan and the US. In accordance with earlier studies, contemporaneous relationships clearly dominate short-term dynamics. The evidence indicates the existence of strong comovements in prices and long-term interest rates, and, to a lesser degree, in GDP and short-term interest rates. They are, however, rather unstable over time.