bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Graphic Programming Environment Based on KAΔMOΣ
Authors: Dulli Susi , Milanese Vitaliano 
Published: March 2003

AbstractIn this paper the design and development of a graphic programming system to be relied on KAΔMOΣ are described. The system architecture upresented together with the functionality of construction and manipulation of the geometric entities. The environment provides an homogeneous handling of both 2D and 3D objects, these last being represented in a complete solid modelling scheme. Handling is achieved through a set of operators designed to manipulate geometric entities in a way suitable to hide users the implementation details of the specific representation domain. Prolog has been used as a common language to implement both the geometric entities supported by a hierarchical construction and their shape constraints.
A Computer Model For Pinscreen Simulation: A New Animation Paradigm
Authors: Lopes Pedro Faria , Gomes Mario Rui 
Published: March 2003

AbstractActual computer image and motion synthesis paradigms are presented in order to introduce a new computer animation paradigm that simulates the traditional pinscreen animation technique. Pinscreen is a very particular and difficult device that enables a “chiaroscuro” approach to image synthesis. The paper describes the traditional pinscreen technique, the way it is operated, results and related difficulties. An extended computer model, including colour and time extensions, to simulate the pinscreen is presented. Results achieved with vector and raster approaches are discussed. Advantages and possibilities of the method when compared with the traditional method and the problems that arise from this technique will also be explained. Finally current and future work is referenced.
An Object‐Oriented View of the User Interface
Authors: Zhou Tom Z.‐Y. , Kubitz William J. 
Published: March 2003

AbstractThe object‐oriented view of the user interface presented here is a model of object responsibilities‐sharing and cooperation for a typical user interface. The model regards the user interface as a three‐layer architecture, with the application contributing to one of the layers called the application exposure, The model seeks to promote user interface software reuse by coupling the user interface and the application with well‐defined message protocols, by properly allocating user interfacefunctions to the layers so as to reduce and discipline their dependencies, and byfactoring complex abstractions into reusable secondary components.
The Visualization Input Pipeline ‐ Enabling Semantic Interaction in Scientific Visualization
Authors: Felger W. , Schröder F. 
Published: March 2003

AbstractScientific Visualization systems are primarily output‐oriented, Users can specify and change parameters that are controlling the visualization process, which will result in different data representations or images respectively. But no mechanism is provided to really interact with the application data (semantic interaction) that has been changed step by step by the process of visualization.In this paper general concepts are elaborated and presented to achieve semantic interaction in dataflow environments for Scientific Visualization.
Fast Generation and Surface Structuring Methods for Terrain and Other Natural Phenomena
Authors: Koh Eng‐Kiat , Hearn D. D. 
Published: March 2003

AbstractFractal geometry has proven to be a powerful tool for modeling natural phenomena. Using discrete approximations to fractional Brownian motion over a finite grid plane, computer graphics terrain‐rendering algorithms are able to generate highly realistic topographical displays. Similar procedures can be applied to model other natural phenomena, such as clouds and water. Two important considerations in these algorithms are computational efficiency and the ability to control macroscopic surface features. Here we introduce a technique for structuring surface features so as to conform to a specified “elevation” envelope. We also present methods for implementing this technique using a recursive random midpoint‐displacement procedure.
The Parametric Differential Method: An Alternative to the Calculation of Form Factors
Authors: Baranoski Gladimir V. Guimaraes 
Published: March 2003

AbstractThe parametric differential method calculates the form factors without using approximations by polygons. Because of this it contributes to the improvement of the realism of the images synthesised through the radiosity method. This paper presents the most important characteristics of the parametric differential method as well as the results concerning its accuracy. Comparison of the form factors found using the new algorithm has been made with those analytically found.
An adaptive Discretization Method For Radiosity
Authors: Languenou Eric , Bouatouch Kadi , Tellier Pierre 
Published: March 2003

AbstractWhen using radiosiiy, the visual quality of the rendered images strongly depends on the method employed for discretizing the scene into patches. A too fine discretization may give rise to artifacts, while with a coarse discretization areas with high radiosity gradient may appear. To overcome these problems, the discretization must adapt to the scene. That is, the interaction between two patches must account for the distance between them as well as their surface area. In other words, surfaces far away are discretized less finely than nearby surfaces. These aspects are considered by the new adaptive discretiration method described in this paper. It performs both discretization and system resolution at each iteration of the shooting process, allowing then interactivity.
A Run‐Length Slice Line Drawing Algorithm without Division Operations
Authors: Fung Khun Yee , Nicholl Tina M. , Dewdney A. K. 
Published: March 2003

AbstractOf the two major approaches to line drawing, run‐length slice algorithms are seldom used because of the division operation deemed necessary in these algorithms. The biggest advantage of these algorithms, the reduction of additions used, is considered outweighed by the division used. In this paper, a new run‐length slice algorithm that does not require a division operation is presented. Furthermore, it uses the double‐stepping paradigm in incremental line drawing algorithms to reduce the number of additions used by at least half.For sufficiently long lines, this algorithm uses at least 50% fewer arithmetic operations than Wu et al.'s bi‐directional double‐step incremental algorithm. But because of its high initialization cost, for short lines, it is less efficient. For a line with endpoints (0,0) and (δx, δy), the strategy is then to use the bi‐directional Bresenham algorithm for very short lines (δx < 20), the bi‐directional double‐step algorithm for moderate long lines (20 ≤δx ≤ 110), and the new algorithmfor the longer lines (δx > 110).
Equidistant Smoothing of Polyhedra with Arbitrary Topologies
Authors: Ma Lizhuang , Liang Youdong , Peng Qunsheng 
Published: March 2003

AbstractSmoothing of polyhedron with arbitrary topology is an important issue in CAGD and CAD/CAM, but so far it is deemed to be difficult to smooth the complex corners of a polyhedron. In this paper, the concept of distance surfaces of a surface and a solid is introduced, and the incisive properties of such surfaces are addressed which provide a theoretical foundation for modifying a general corner. The method is based on making constricted volume and the maximum distance the volume can be constricted is given too. It is shown that by the proposed method in this paper any polyhedron can be G1 smoothed with quadraic and, sometimes toroidal surfaces. The new approach is suitable for engineering design and NC machining. The associated algorithm based on the classification theorem of corners is simple, fast and robust.
A Simple Description of Complex Curves
Authors: Bouras A. , Shariat B. , Vandorpe D. 
Published: March 2003

AbstractIn this paper, we propose a method of complex curves description, based on the use of standard primitives (curve arcs), inscribed in including boxes. This method simplifies the creation steps (curves are not defined with the help of control points), and the manipulation steps (using including boxes).This study constitutes an extension to our descriptive universal language, named “G”, which is used in a general desig n environment, permitting the integration of various models (solids1, polyhedrons2, surfaces3 and fractals), in order to offer the adequate tools adapted to the problems to be solved, in a unique modeller.
Interactive Shape Control of Interpolating B‐splines
Authors: Krokos M. A. , Slater M. 
Published: March 2003

AbstractThis paper presents a new methodfor providing interactive shape control of interpolating B‐splines. The CAD designer can directly interact with geometric entities defined on the B‐spline at any interpolated data point; shape adjustments can be performed either globally or locally. Our approach is based on Bλ‐splines of order k (λ,k ≥1), i.e. λ‐reparametrized, classical B‐splines. The method presented can be easily generalised to surfaces defined either as tensor products or by using the skinning technique; interactive shape control can be provided in both surface parametric directions.
Combined Direct and Inverse Kinematic Control for Articulated Figure Motion Editing
Authors: Boulic Ronan , Thalmann Daniel 
Published: March 2003

AbstractA new approach for the animation of articulated figures is presented. We propose a system of articulated motion design which offers a full combination of both direct and inverse kinematic control of the joint parameters. Such an approach allows an animator to specify interactively goal‐directed changes to existing sampled joint motions, resulting in a more general and expressive class of possible joint motions. The fundamental idea is to consider any desired‐joint space motion as a reference model inserted into the secondary task of an inverse kinematic control scheme. This approach profits from the use of half‐space Cartesian main tasks in conjunction with a parallel control of the articulated figure called the coach‐trainee metaphor. In addition, a transition function is introduced so as to guarantee the continuity of the control. The resulting combined kinematic control scheme leads to a new methodology of joint‐motion editing which is demonstrated through the improvement of a functional model of human walking.
Consistent Schemes for Addressing Surfaces when Ray Tracing Transparent CSG Objects
Authors: Gervautz Michael 
Published: March 2003

AbstractConstructive Solid Geometry (CSG) defines the shape of objects, i.e. the inside and the outside regions of objects, but it does not define the material properties of the space in the interior of objects. The definition is ambiguous. There are points of space lying in several primitives, which can consist of different materials. When visualizing transparent objects this ambiguity leads to strange results, which are not consistent with the CSG modelling scheme and must therefore be eliminated. This work describes how an unambiguous model can be built by asymmetric CSG‐operators and how correct refraction and shading on material boundaries can be established by separating surface properties from material properties. This separation leads to a consistent view of CSG modelling also concerning materials and surfaces. Ray tracing CSG trees and the shading model are influenced by these asymmetric operators. We introduce an applied classification scheme to handle the requirements of the new operator definition.
Verve
Authors: Knittel Günter 
Published: March 2003

AbstractThe design principles of a hardware acceleratorfor volume rendering are described. The architecture represents a voxel subsystem which interfaces easily to any existing workstation. Host requirements are low since it contains a multiport memory holding the complete data set and all arithmetic units needed to perform an effective visualization.Our approach aims at virtual reality by providing some “real‐world” examination techniques. The user (e.g., a physician) is enabled to analyze the data set from an arbitrary viewpoint and, even more, to “walk through” the volume model. For a realistic impression, the machine produces perspective projections, supports the illumination by non‐parallel light comingfrom a freely movable point light source and provides depth cueing. The objects are Phong shaded at a rate of 107 operations/s and can be displayed semitransparently. One unit achieves interactive speed: for real‐time operation only a small number of units (typically 4‐16) must be placed in parallel.
Interactive Neural Network Texture Analysis and Visualization for Surface Reconstruction in Medical Imaging
Authors: Busch C. , Groß M.H. 
Published: March 2003

AbstractThe following paper describes a new approach for the automatic segmentation and tissue classification of anatomical objects such as brain tumors from magnetic resonance imaging (MRI) data sets using artificial neural networks. These segmentations serve as an input for 3D–reconstruction algorithms. Since MR images require a careful interpretation of the underlying physics and parameters, we first give the reader a tutorial style introduction to the physical basics of MR technology. Secondly, we describe our approach that is based on a two–pass method including non–supervised cluster analysis, dimensionality reduction and visualization of the texture features by means of nonlinear topographic mappings. An additional classification of the MR data set can be obtained using a post–processing technique to approximate the Bayes decision boundaries. Interactions between the user and the network allow an optimization of the results. For fast 3D–reconstructions, we use a modified marching cubes algorithm but our scheme can easily serve as a preprocessor for any kind of volume renderer.The applications we present in our paper aim at the automatic extraction and fast reconstruction of brain tumors for surgery and therapy planning. We use the neural networks on pathological data sets and show how the method generalizes to physically comparable data sets.
Storage Support for Multidimensional Discrete Data in Multimedia Databases
Authors: Furtado Paula , Teixeira Jose Carlos 
Published: March 2003

AbstractMultidimensional discrete data (MDD) is enormously important for multimedia applications since diverse types of such data are used simultaneously by any multimedia application. However, multidimensional discrete data is not adequately supported by most existing database systems.In this paper we discuss the major management requirements imposed by such data on multimedia database management systems both at the conceptual level and at the internal level. At the internal level, the spatial structure of the data must also be preserved and special emphasis must be given to the efficient spatial access to subrectangles of very large data of arbitrary dimensionality.Our major contribution is the presentation of a Storage Manager for this kind of data which preserves the spatial nature of the data at the internal level of the database management system and provides efficient spatial access. This Storage Manager is based on an innovative combination of the subdivision of data in multidimensional tiles and of a spatial index to access those tiles. Furthermore, it supports advanced registration data.The lower level modules of the Storage Manager are responsible for the access to the data stored in secondary storage. The implementation of these modules can rely on any secondary storage access system to access data on disk. The Storage Manager was implemented using the functionality of a relational database system. The implementation of this relational Storage Manager is presented.
Updating Polygonizations*
Authors: Abellanas M. , Garcia J. , Hernbández G. , Hurtado F. , Serra O. , Urrutia J. 
Published: March 2003

AbstractIn this paper we consider polygonizations that are robust when faced with changes in the vertices that are present or in their position. We analyze the dynamic maintenance of different types of polygonizations (monotone, star‐shaped…) and we introduce monotone half‐convex polygonizations that are specially interesting because they provide minimum cost per insertion or deletion. If we had to delete not only one point but several external layers of the set, then the onion polygonizations would be suited, because they can be updated in constant time. We also consider the case of points that can be moved to contiguous positions and we show how to polygonize the set for updating in linear time. We deal too with security problems for a polygon: What is the maximum distance the vertices of a polygon could be moved away of their position in such a way that the topology on the boundary of the polygon (or its convexity) remains the same?.
Introducing blending operations in feature models
Authors: Laakko Timo , Mäntylä Martti 
Published: March 2003

AbstractWe describe the implementation of a blending facility in the context of a feature modelling system where solid and feature‐based modelling operations can be utilized in parallel during the design process of a part. The definition of blends can be done in a graphical user interface by selecting edges to be blended. Feature recognition of blends facilitates the definition process of blends. Alternatively, a special feature editor can be used to add blends to the feature model. The particular implementation style chosen gives rise to aflexible and easy‐to‐use modelling tool.
Direct 3D Manipulation Techniques for Interactive Constraint‐based Solid Modelling
Authors: Fa Mingxian , Fernando Terrence , Dew Peter M. 
Published: March 2003

AbstractThis paper presents a novel constraint‐based 3D manipulation approach to interactive constraint‐based solid modelling. This approach employs a constraint recognition process to automatically recognise assembly relationships and geometric constraints between entities from 3D manipulation. A technique referred to as allowable motion is used to achieve accurate 3D positioning of a solid model by automatically constraining its 3D manipulation without menu interaction. A set of virtual design tools, which can be used to construct constraint‐based solid models within a virtual environment, are also supported. These tools have been implemented as functional 3D objects associated with several pre‐defined modelling functions to simulate physical tools such as a drilling tool and T‐square. They can be directly manipulated by the user, and precisely positioned relative to other solid models through the constraint‐based 3D manipulation approach. Their modelling functions can be automatically triggered, depending upon their associated constraints and the user's manipulation manner. A prototype system has been implemented to demonstrate the feasibility of these techniques for model construction and assembly operations.
Extracting contour lines from a hierarchical surface model
Authors: De Floriani Leila , Mirra Daniela , Puppo Enrico 
Published: March 2003

AbstractThe Hierarchical Triangulated Irregular Network (HTIN) is a structure for representing 2½‐dimensional surfaces at different levels of detail through piecewise‐linear approximations based on triangulations of the surface domain. In this paper, we present two algorithms that allow extracting a representation of the surface and contour lines at a given level of detail, directly from the HTIN.
A 4D Ray Tracing
Authors: Maurel Herve , Duthen Yves , Caubet René 
Published: March 2003

AbstractWe are going to present a survey of techniques using temporal coherence in between frames to render animation sequences with ray tracing. A new method using temporal coherence in the ray space (lightpath of rays) is proposed. The goal of this technique is to factorize intersection and illumination calculations over the frames of the sequence. An optical event springing out many times in the sequence is computed once. The method is based upon 4D intersection calculations between temporal rays and moving objects. At the end of this paper, we present measurements showing the number of rays we need not calculate with our solution. These results come from simulating the algorithm behavior through a graphic and statistic ray analyser tool.
DaScript3D Integrating 3D Graphics in a Page Description Language
Authors: Samara Veronika 
Published: March 2003

AbstractDespite the necessity of producing high‐quality documents comprising all aspects of electronic publishing, there is still no system available that can generate and integrate two‐dimensional (2D) graphics, three‐dimensional (3D) graphics and high‐quality text electronically. This situation becomes especially critical in the area of technical documentation where graphics as well as text play a major role. DaScript3D introduces 3D extensions able to handle and integrate 2D and 3D graphics as well as text in one tool. Based on the page description language PostScript, DaScript3D offers the power of PostScript on the one hand, and, on the other hand, all the characteristics and advantages of a 3D system.
Pseudo‐Satellitefilm Using Fractal Clouds to Enhance Animated Weather Forecasting
Authors: Sakas Georgios , Schröder Florian , Koppert Hans‐Joachim 
Published: March 2003

Abstract:We have developed a system enabling the National German Meteorological Office to generate pseudo‐satellite images and video sequences based on their weather forecasting simulation data. With our system meteorologists can visualize the past and the current weather situation, evaluate their simulation results, and produce animated weather forecast videos broadcasted by several television stations. Realistic images are generated by interpolating the extremely coarse weather simulation data grid and enhancing the result using fractal clouds. It also enables the meteorologists to interactively change the forecast data in order to compensate the lack of accuracy or the known errors in their simulation models. Our system TRITON enables the visualization of complex weather simulations in a more natural way by presenting an intuitively understandable forecast.
Photo‐Realistic Imaging of Digital Terrains
Authors: Cohen Daniel , Shaked Amit 
Published: March 2003

AbstractWe present a method for the generation of photo‐realistic images of views over terrain datasets by mapping a digital aerial photograph on a perspective projection of a digital elevation map. We use high resolution for both digital maps to increase the quality and the realism of the image at the cost of the overhead of processing very large data bases. In the core of this paper we present an accelerated ray casting technique based on a new algorithm of traversing a pyramidal data structure. Unlike other known traversal techniques, the cost of a single step of the algorithm consists of a few additions, shifts and comparisons only.
A New Radiosity Approach Using Area Sampling for Parametric Patches
Authors: Nishita Tomoyuki , Nakamae Eihachiro 
Published: March 2003

AbstractA high precision illumination model is indispensable for lighting simulation and realistic image synthesis. For the purpose of improving realism, research on global illumination has been done, and several papers on radiosity methods have been presented. In the most recently proposed methods, the shapes of light sources and objects are restricted to polygons or simple curved surfaces. We present a more general method which can handle the kind of free‐form surfaces widely used in industrial products and in architecture. The method proposed here solves the problem of the interreflection of light (i.e., radiosities) between patches, and form‐factors, which play an important role in this process, are precisely calculated without aliasing through the use of an area sampling method (i.e., pyramid tracing). Furthermore the method can handle both non‐uniform intensity curved sources and non‐diffuse surfaces.