The last few years have witnessed tremendous growth in the complexity of computer graphics models as well as network-based computing. Although significant progress has been accomplished for handling large datasets on single graphics workstations, solutions for network-based graphics and virtual environments are woefully inadequate. The situation is set to worsen in the future, with graphical models becoming increasingly complex. One of the most effective ways of managing the complexity of virtual environments is through the application of smart visibility methods.
Visibility determination, the process of deciding what surfaces can be seen from a certain point, is one of the fundamental problems in computer graphics. It is required not only for the correct display of images but also for such diverse applications as shadow determination, global illumination, culling and interactive walkthrough.
The importance of visibility has long been recognized, and much research has been conducted in this area in the last three decades. The proliferation of solutions, however, has made it difficult for the non-expert to deal with effectively. Meanwhile, in network-based graphics and virtual environments, visibility has become a critical issue, presenting new problems that need to be addressed.
In this tutorial we will review the fundamental issues in visibility
and conduct an in-depth study of the algorithms developed in recent years.
We will also identify existing problems and discuss various unresolved
issues. The tutorial will serve as an introduction for the beginner, as
well as providing directions for future research for the more experienced
practitioners.
II. Occlusion culling techniques (60 min)
Speaker: Anthony
Steed
Powerpoint
slides
III. Hierarchical methods (30 min)
Speaker: Vladi Koltun
Powerpoint
slides
IV. Binary Space Partitioning trees (45 min)
Speaker: Yiorgos
Chrysanthou
Powerpoint
slides,
some
notes on BSP trees
V. Viewspace partitioning and strong occlusion (30 min)
Speaker: Vladi Koltun
Powerpoint
slides
Daniel Cohen-Or is a senior lecturer at the Department of Computer Science since 1995. He received a B.Sc. cum laude in both Mathematics and Computer Science (1985), an M.Sc. cum laude in Computer Science (1986) from Ben-Gurion University, and a Ph.D. from the Department of Computer Science (1991) at State University of New York at Stony Brook. He has been a lecturer at the Department of Mathematics and Computer Science of Ben Gurion University in 1992-1995.
He is on the editorial advisory board of the international Computers and Graphics journal. He is the Program Co-chair of the symposium on volume visualization to be held in the year 2000. He is a member of the program committees of several international conferences on visualization and computer graphics, including IEEE Visualization, Eurographics and the Eugraphics redendering workshop. Between 1996-8 he served as the Chairman of the Central Israel SIGGRAPH Chapter.
Dr. Cohen-Or has a rich record of industrial collaboration. In 1992-93 he developed a real-time flythrough with Tiltan Ltd. and IBM Israel for the Israeli Air Force. During 1994-95 he worked on the development of a new parallel architecture at Terra Ltd. In 1996-1997 he has been working with MedSim Ltd. on the development of an ultrasound simulator. He is now also involved with Webglide Ltd. His research interests are in Computer Graphics, and include rendering techniques, client/server 3D graphics applications, real-time walkthroughs and flythroughs, volume graphics, architectures and algorithms for voxel-based graphics.
Yiorgos Chrysanthou
Department of Computer Science
UCL University of London
Gower Street, London WC1E 6BT, UK
E-mail: Y.Chrysanthou@cs.ucl.ac.uk
Phone:
FAX:
Yiorgos Chrysanthou is a lecturer in the Computer Science Department of University College London, UK. He received his BSc in Computer Science and Statistics (1990, 1st Class Honours) and his PhD in Computer Graphics (1996) from Queen Mary and Westfield College. During the period of 1996-98 he worked as a research fellow on the COVEN (Collaborative Virtual ENvironments) ACTS project where he concentrated on real-time rendering of large scale virtual environments. Recently he co-edited, along with Daniel Cohen-Or, a special in the journal Computers and Graphics with theme Visibility, techniques and Applications. His research interests include real-time rendering, virtual reality and computational geometry.
Anthony Steed
Department of Computer Science
UCL University of London
Gower Street, London WC1E 6BT, UK
E-mail: Y.Chrysanthou@cs.ucl.ac.uk
Phone:
FAX:
Anthony Steed currently works on the EU ACTS Programme COVEN (ACTS N. AC040) and the Virtual Rehearsal for Actors project of the Virtual Centre of Excellence in Digital Broadcasting and Multimedia. His research interests are in interaction with virtual environments and supporting groups of participants within collaborative virtual environments. He is also very involved with the Web3D Consortium's standardisation efforts. He was involved in organising the First International Workshop on Usability Evaluation for Virtual Environments held on the 17th of December 1998 at De Montfort University, Leicester, UK and is one of the local organisers for VRST99.
Vladi Koltun
Computer Science Department
School of Mathematical Sciences
Tel-Aviv University, Ramat-Aviv 69978, Israel
E-mail: vladlen@email.com
Phone: +972-3-640-8828
FAX: +972-3-640-9357
Vladi Koltun is a graduate student in Computer Science at Tel-Aviv University.
Through a number of personal projects and his work as a senior developer
for a computer graphics software company, he has acquired rich experience
in computer graphics techniques. Currently he is a visiting researcher
at the VR group in UCL, where he is developing a novel Visibility Culling
technique.