Colloquy Cycle WS 1998/1999

• Colloquy Cycle SS98
• Colloquy Cycle WS97/98
• Colloquy Cycle SS97
• Colloquy Cycle WS96/97

Global Visualization -- And Beyond

William Ribarsky, Georgia Institute of Technology, USA

I will describe work to depict, explore, and understand large scale to very large scale data. For data of this size, one cannot just consider visualization techniques alone but must consider them in conjunction with issues of data organization, interactivity, data paging and memory management, efficient visual representation, overall detail management, and techniques for exploration and discovery. Efficiency becomes predominant, time is of the essence, and exploration is key (since nobody will know, in detail, what a very large dataset contains). I will show that these issues are not just important for the applications presented but have much wider applicability.

Hierarchical and Monte Carlo Techniques for Radiosity

Philippe Bekaert, Katholieke Universiteit Leuven, Belgium

Since the introduction of the radiosity method for image synthesis in 1984, many improvements to it have been proposed. Some of these, such as the computation of form factors using the hemicube algorithm and Southwell iterations for solving the radiosity set of equations, have made that the radiosity method begins to emerge in commercial rendering software systems. These techniques appeared in scientific literature more than 10 years ago.

In this talk, I will give an overview of techniques that appeared since then to make the radiosity method more efficient, user friendly and reliable. Two of these, hierarchical refinement, based on wavelet theory, and the solution of the radiosity system of equations by using Monte Carlo simulation, will be discussed in more detail. A combination of hierarchical refinement and Monte Carlo promises to make radiosity feasible for complex models, even on low cost platforms.

A Generalized Form of Parametric Equations for Planar Second-order Curves

Leo Budin, University of Zagreb, Croatia

A mathematical model for shading analysis developed for purposes of solar engineering is described. Closed form expressions giving the position of the shadow as a function of time for an isolated point are derived. It was found that these expressions define second-order planar curves. Furthermore, the developed equations can be expressed in generalized parametric form enabling a smooth transition between different curves of the same class. Feasibility of these expressions for computer graphics should be further investigated.

Die Wunderkammer - Inspirationsraum für Architektur und Design

Martin Kompast und Ina Wagner, TU Wien

Die Wunderkammer ist als Teil einer kollaborativen elektronischen Arbeitsumgebung für Architekten, Landschaftsplaner und andere design-orientierte Professionen gedacht. Sie wird gegenwärtig im Rahmen des Esprit LTR Projekts DESARTE entwickelt. Die Wunderkammer ist ein multi-mediales Archiv, das das Sammeln und Entdecken inspirationaler Objekte und ihre Darstellung unterstützt. Topographie und Erscheidungsbild sollen der visuellen Kultur der jeweiligen Designdisziplin entsprechen, und beispielweise als modular aufgebauter, symbolischer Stadtraum oder als fliessende Abfolge von Landschaftsformationen gestaltet sein. Feldarbeit im Architekturbüro gibt Aufschluß über die Bedeutung inspirationaler Objekte (dies mögen Bilder, Skizzen, metaphorische Beschreibungen, Filmausschnitte usw. sein) sowohl für die Entwurfsarbeit selbst, als auch für die Kommunikation von Projektideen nach aussen. BenutzerInnen sollen in der Wunderkammer ihre eigene Sammlung anlegen und diese mit anderen teilen können. Es sollen verschiedene Modi des Bereisens und Entdeckens sowie des erzählenden Zusammenfügens von Objekten (als Collage, Animation, Film usw.) unterstützt werden. Sie sollen letztlich ihre eigene Wunderkammer-Welt gestalten können.

Ray shooting algorithms and data structures for Computer graphics

Vlastimil Havran, Czech Technical University

Ray shooting is one of the most important problems for computer graphics. The efficiency of the algorithms for ray shooting has great impact on the performance of many global illumination algorithms. In this talk we give a short survey to various methods developed for ray shooting from the perspective of computational geometry and computer graphics. Particularly, we will focus on the concepts of orthogonal Kd-trees more often referred to as BSP trees in computer graphics. Recent developments in ray shooting will be discussed.

Visibility in Computer Graphics

Jiri Bittner, Czech Technical University

I will introduce a classification of visibility problems in three dimensions that is based on the dimension of the space of lines involved in the problem. In particular the following three classes will be discussed: visibility along a line, visibility from a point, and visibility from a region. Further, I will present a conservative hierarchical visibility algorithm for a moving viewpoint that is suitable for real time visibility culling. The algorithm uses occlusion tree that is a modification of the shadow volume BSP tree. Finally, I will mention some general refinements that make use of spatial and temporal coherence in the scope of hierarchical visibility algorithms.