EG1999

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WebTalk: a 3D collaborative environment to access the Web
(Eurographics Association, 1999) Paolini, P.; Barbieri, T.; Loiudice, P.; Alonzo, F.; Arru, M.; Zanti, M.; Gaia, G.
The notion of cooperative visit and interaction within a web site, both at 2D and 3D level, could add decisive motivation to pursue exploitation of the third dimension in networked environments. A prototype developed at the HOC laboratory in Politecnico of Milan, WEBTALK, allows development of custom 3D environments in which actions and situations can be shared throughout a network. The current prototype makes use of standard web-based Internet/Intranet technology: it is composed of a VRML (Virtual Reality Modeling Language) graphical engine and a Java-based TCP/IP (the Internet Protocol) communication layer. The technique has proven itself successful and has given rise to several interesting applications, such as the creation of Virtual 3D Museum Spaces at the National Science Museum (www.museoscienza.org), in which visitors can visit the museum interacting with the exhibits themselves and sharing their experiences with other visitors - even joining a guided tour with the virtual museum guide. A new prototype will make use of a completely Java-based environment, using Sun’s Java 2 and Java 3D. The new WEBTALK will stress even further the issues of third party external authoring of virtual worlds and of cooperation patterns within the shared environments, with a distinction between shared object geometries, shared object behaviors, shared object data (stored in an on-line DBMS), and cooperation metaphors within the virtual world. Linking to 2D-based web sites resources will lead cooperation patterns to be extended also to regular web-space.
Visual Learning with Computer Art Graphics Artwork Description
(Eurographics Association, 1999) Ursyn, Anna
In my work, I use the computer on different levels. For my two-dimensional works, I have been programing in Fortran IV then Fortran 77 using Cyber, then VAX mainframes and Interactive Graphic Library (IGL). I have been setting color combinations, transforming light intensity, applying grid patterns and moir effects in order to gain composition. The two-dimensional programs serve as a point of departure for photolithographs after computer programs and photo silkscreened prints on canvas and paper; they are included both into my two-dimensional and three-dimensional works. Scanners, digital camera and PC/PPCs serve for further image manipulation. All of these approaches are combined for image creation with the use of painterly markings. Printouts have been obtained in several ways: first, black-and white plots from the Versatec plotter and color slides via the Computer Output Microfilmer (COM) recorder, then the Apple, Hewlett-Packard, and Novajet printers/plotters.
Graph Visualisation and Navigation in Information Visualisation
(Eurographics Association, 1999) Herman, I.; Melancon, G.; Marshall, M.S.
This is a survey on graph visualisation and navigation techniques, as used in information visualisation. Graphs appear in numerous applications, like web browsing, state–transition diagrams, computer data structures, etc. The ability to visualise and to navigate in these potentially very large, abstract graphs is often a crucial part of an application. Information visualisation has specific requirements, which means that this survey approaches the results of traditional graph drawing from a different perspective than the traditional surveys; as such it is a useful complementary survey to those
Creating light-weight virtual humans for Virtual Environments
(Eurographics Association, 1999) Oliveira, Joao; Buxton, Bernard
With the advent of whole body, 3D electro-optical scanners, a new range of applications are emerging that exploit the availability of personalised, realistic human models. However, realistic rendering of such models usually entails a large number of polygons which can be unacceptable in many applications. We present a framework that exploits the approximate cylindrical and spherical symmetry of human body parts to create light-weight representations that retain the overall dimension of body parts, even at very low polygon counts.
Graphics, Vision, and Visualization in Medical Imaging: A State of the Art Report
(Eurographics Association, 1999) Ezquerra, Norberto; Navazo, Isabel; Morris, Tahia Infantes; Monclus, Eva
The field of medical imaging has significantly changed over the years, becoming both an integral part of health care and an increasingly important area of research spanning many disciplines. As the title of this paper suggests, one interesting result of this evolutionary process has been the fusion of traditionally disjointed yet highly interrelated areas: from computer vision and image processing, through graphics and visualization, to the integration of creative immersion and robotics-based mechanisms for interactively manipulating the information. As a result of these innovations, medical imaging has continued to re-invent itself, fundamentally changing the ways in which we see, communicate about, learn from, and interact with, medical information. With this in mind, the purpose of this state-of-the-art (STAR) report is two-fold. On one hand, the aim is to provide a brief summary of some of the salient methods, results, and potentially powerful trends that currently describe the field. On the other hand, the goal is to outline some of the remaining challenges as well as the possible opportunities. Clearly, the field is far too broad and complex for a single article to adequately reflect the technical depth and extraordinary diversity of even a small portion of these topics. Thus, without any claim at completeness, the emphasis will be placed on highlighting selected frontier research activities and applications, focussing on aspects related to vision, graphics and visualization from an interpretive (rather than tutorial) perspective. In addition to these discussions, a list of URLs of some of the groups actively engaged in medical imaging research is also included. The overall objective is therefore to provide a "snap shot" of the field through a brief summary that will hopefully serve as a useful source of information for those wanting to learn more about the field, and, for those actively engaged in the field, a timely -and possibly inspirational- reference.
Modelling and Haptic Interaction with non-rigid materials
(Eurographics Association, 1999) Cugini, U.; Bordegoni, M.; Rizzi, C.; De Angelis, F.; Prati, M.
This report presents an overview of main modelling and simulation techniques for non–rigid objects discussing advantages and disadvantages. Related techniques to face several problems rising when dealing with deformable objects simulation are also discussed. They concern numerical solvers, constraints management and collision detection. In the simulation of non-rigid objects another relevant issue is the provision of operational modality at higher and higher level and more and more useroriented. The paradigm of haptic interaction recently developed seems promising to achieve this goal. Haptic interaction allows the users to feel several physical properties of the modelled objects through the manipulation of their virtual representation. Thus, second part of the report focuses on the state-of-theart of haptic devices, technologies and applications concerning interaction with non-rigid models. A classification from different point of views is proposed. The specific work our group is performing in the area of non-rigid objects modelling and simulation and haptic interaction with non-rigid models is also illustrated.
A Rapid Clustering Algorithm for Efficient Rendering
(Eurographics Association, 1999) Müller, Gordon; Schäfer, Stephan; Fellner, Dieter W.
Hierarchical radiosity using object clusters greatly improves rendering times and reduces memory consumption of radiosity computations. The key feature of the algorithm is using a hierarchy of object clusters to approximate the energy exchange between surfaces. The cluster hierarchy used for this purpose however, must accurately reflect the actual scene geometry to justify this approach. Bad clusters easily lead to rendering artifacts. Inspired by the results of our hierarchical bounding volume optimization for ray tracing, we applied the same scheme to a clustering algorithm for hierarchical radiosity. Using an object-oriented framework, the extension of the implementation was straight forward and seems to be promising. Due to the good performance of our hierarchy regarding ray tracing, the same data structure could successfully be used for two things: visibility checks based on ray casting and energy exchange for the radiosity computation. In this short paper, first results regarding our new clustering scheme will be presented. The properties of the underlying bounding volume optimization give reason for interesting applications enhancing various rendering techniques. Some of these new ideas will be discussed here.
Tutorial 9 - Visibility
(Eurographics Association, 1999) Chrysanthou, Yiorgos L.; Cohen-Or, Daniel; Fibich, Gadi; Halperin, Dan; Zadicario, Eyal; Lev-Yehudi, Shuly; Bartz, Dirk; Meißner, Michael; Hüttner, Tobias; Hüttner, Tobias; Bittner, Jiri; Havran, Vlastimil; Slavik, Pavel; Klosowski, James T.; Silva, Claudio T.
The focus of this tutorial is a study of the techniques for solving visibility problems in virtual walkthroughs. The term walkthrough is referring not only to models of architectural models but rather to any large complex model, where the focus is on viewing and rendering the model. The tutorial touches on several applications such as fast visible surface determination, selection of relevant model sections to be transmitted on a client-server system, as well as improving image quality by shading algorithms.
Monitoring of the visual arts degrade by means of the active vision system “3EYES”
(Eurographics Association, 1999) Cojoc, D.; Grattoni, P.; Nerino, R.; Pettiti, G.
Monitoring of some physical characteristics (colour, geometry, size of fissures, ...) of object surfaces is of utmost importance in the field of conservation and restoration of work of arts. In order to get effective results a very high repeatability in the localization of the test points is required. At present, repositioning is a tricky task and is performed by means of manual empirical procedures which can be time consuming and expensive. In this short paper an application of the 3EYES active vision system to the automation of the monitoring is presented. An application of the system to object monitoring in laboratory environment is described.
The atrium of St. Mary Abbey in Pomposa: a hypermedial 3-D network database
(Eurographics Association, 1999) Alessandri, Claudio; Gaiani, Marco
The analysis carried out on the atrium of the church of Pomposa is an example of a multidisciplinary experience which gathered historians, computer analysts, structural and computer graphics experts on the same project. A 3-D virtual model and the related data base can be considered a common basis for the different approaches attempted and tools indispensable to a correct representation of the complexities characterizing the atrium.
Interactive Information System for the Camposanto Monumentale of Pisa
(Eurographics Association, 1999) Baracchini, C.; Brogi, A.; Merlitti, D.
Multimedia Database gathering the historical-preservative documentation of the monumental complex, including a digital reconstruction achieved through a solid modelling of the building and its fittings.
A Study of Automatic Program Production Using TVML
(Eurographics Association, 1999) Douke, Mamoru; Makino, Eiji; Hayashi, Masaki
This paper describes a method to create TV programs automatically using TVML(TV program Making Language). TVML is a scripting language that we have developed for generating TV programs by computer. In this paper, we focus on automatic news program creation. We define XML tags for describing contents of a news program, and presentation data for creating the program by given XML file. We have also developed an automatic news program creation software based on the idea.
Contour Extraction of Watermarks in Old Manuscripts
(Eurographics Association, 1999) Wenger, Emanuel; Karnaukhov, Victor N.; Haidinger, Alois
The comparison of watermarks in old paper is the major technique for dating undated medieval manuscripts. The extraction of watermarks as contours is the crucial task in digitalization and building a watermark database. In this paper the method of object delineation by active curves (snakes) is modified and applied to the contour tracing and skeletonization of watermarks.
A Minimalist Approach to Facial Reconstruction
(Eurographics Association, 1999) Gotla, M.; Huang, Z.
We propose a minimalist approach to 3D facial reconstruction. By applying cognitive and anatomical heuristics, we show that a realistic face model can be reconstructed from a generic face model using only one or two real facial images and minimal user interaction.
Animating Brachiation
(Eurographics Association, 1999) Zhang, Zheng; Wong, Kok Cheong
This paper presents a physically-based animation system for generating realistic motion of primate brachiation. One of the main aims of this system is to facilitate the process of generating brachiation sequences with appropriate automaticity and also provide the animator with adequate controllability. A hybrid system based on an integration of three control modules of different levels. The low-level control module, namely forward dynamics interactive module can be employed to rapidly manipulate the torque values at specific joints of a simplied primate figure. Both the mid-level and high-level control modules are designated to automate the process of generating the basic global brachiation movements of the primate figure. The performance of the system is evaluated by measuring the animation results qualitatively and quantitatively. Experimental results have demonstrated the effectiveness and robustness of the paradigm by generating animated sequences of realistic brachiating motion
Registration methods for harmonious integration of real worlds and computer generated objects
(Eurographics Association, 1999) Simon, G.; Lepetit, V.; Berger, M.-O.
This page is an extension of our paper entitled "Registration methods for harmonious integration of real and computer generated objects". We focus in this paper on the problem of adding computer-generated objects in video sequences. We propose a robust method for viewpoint computation which utilizes 3D knowledge on the scene as well as 2D/2D correspondences of key-points. Next, we extend this method to the case of unknown focal length varying from image to image. Finally, we describe how to solve possible occlusions between the computer generated objects and the real scene. Many videos illustrating these different points are presented here.
Tutorial 6 - Rendering and Visualization in Parallel Environments
(Eurographics Association, 1999) Bartz, Dirk; Schneider, Bengt-Olaf; Silva, Claudio
The continuing commoditization of the computer market has precipitated a qualitative change. Increasingly powerful processors, large memories, big harddisk, high-speed networks, and fast 3D rendering hardware are now affordable without a large capital outlay. A new class of computers, dubbed Personal Workstations, has joined the traditional technical workstation as a platform for 3D modeling and rendering. In this tutorial, attendees will learn how to understand and leverage both technical and personal workstations as components of parallel rendering systems. The goal of the tutorial is twofold: Attendees will thoroughly understand the important characteristics workstations architectures. We will present an overview of different workstation architectures, with special emphasis on current technical and personal workstations, addressing both single-processors as well as SMP architectures. We will also introduce important methods of programming in parallel environment with special attention how such techniques apply to developing parallel renderers. Attendees will learn about different approaches to implement parallel renderers. The tutorial will cover parallel polygon rendering and parallel volume rendering. We will explain the underlying concepts of workload characterization, workload partitioning, and static, dynamic, and adaptive load balancing. We will then apply these concepts to characterize various parallelization strategies reported in the literature for polygon and volume rendering. We abstract from the actual implementation of these strategies and instead focus on a comparison of their benefits and drawbacks. Case studies will provide additional material to explain the use of these techniques. The tutorial will be structured into two main sections: We will first discuss the fundamentals of parallel programming and parallel machine architectures. Topics include message passing vs. shared memory, thread programming, a review of different SMP architectures, clustering techniques, PC architectures for personal workstations, and graphics hardware architectures. The second section builds on this foundation to describe key concepts and particular algorithms for parallel polygon rendering and parallel volume rendering.
A Global Routing Mechanism for Modular VRML-Worlds
(Eurographics Association, 1999) Mader, S.
With the increasing complexity of virtual worlds VRML97 reveals its lack of native support for logical modularization of these worlds. Though the inherent mechanisms as PROTO-typing and Inlining allow us to partition our worlds into several files, the restriction to file-limited namespaces makes an event-routing for complex interactions between different modules a rather difficult task. In this paper we present an easy-to-use method for event-based communication across modular VRML scenes. Based on VRML´s event model, this solution goes conform with the VRML97 standard ISO/IEC 14772-1:19971 . In order to show its ability to support the implementation of highly interactive and complex VRML-worlds we demonstrate its application in a current project from the fields of virtual heritage.
Wavelet Projections for Volume Rendering
(Eurographics Association, 1999) Horbelt, Stefan; Unser, Michael; Vetterli, Martin
We extended Gross’s 3 method of volume wavelet rendering by computing splats via an orthogonal projection operator. The method decomposes the volume data into a wavelet pyramid representation in the spline domain. The splats of the basis functions are approximated on a multiresolution grid. Using least-squares approximation ensures the smallest possible error for a given sampling step size. The approximation error on the grid is derived as a function of the sampling step h. The choice of the appropriate wavelet space and spatial resolution at each step produces the smallest possible filters. Our approach reduces the number of computations and allows full control of the image quality.
Tutorial 1 -Advanced Radiosity:Complex Scenes and Glossy Reflections
(Eurographics Association, 1999) Stamminger, Marc; Wexler, Daniel; Kresse, Wolfram; Holzschuch, Nicolas; Christensen, Per H.
A lot of research towards global illumination has been focussed on the radiosity method. Nevertheless, it is still a rather academic topic which finds very slowly its way into commercial products. The scope of this tutorial is to describe recent developments in radiosity research that might narrow the gap with commercial applications. The first part of the tutorial course will be given by a pioneer in commercial computer graphics, who will set the stage for the demands of commercial rendering products and assess why radiosity has not been used until now.

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