Eurographics 2009 Tutorial #4

Timo Ropinski, Christof Rezk-Salama, Markus Hadwiger, Patric Ljung

http://www.eurographics2009.de/program/tutorials/ 

Summary Statement

The course presents and in-depth tutorial to advanced illumination techniques for volume raycasting implemented on the graphics processing unit (GPU). The course covers fast implementations of local and global illumination techniques for volume data and implicit surfaces, including ambient occlusion, deep shadow maps, and scattering effects.

Tutorial Abstract

Volume raycasting techniques are important for both visual arts and visualization. They allow an efficient generation of visual effects and the visualization of scientific data obtained by tomography or numerical simulation. Thanks to their flexibility, experts agree that GPU-based raycasting is the state-of-the art technique for interactive volume rendering. It will most likely replace existing slice-based techniques in the near future. Volume rendering techniques are also effective for the direct rendering of implicit surfaces used for soft body animation and constructive solid geometry. The lecture starts off with an in-depth introduction to the concepts behind GPU-based ray-casting to provide a common base for the following parts. The focus of this course is on advanced illumination techniques which approximate the physically-based light transport more convincingly. Such techniques include interactive implementation of soft and hard shadows, ambient occlusion and simple Monte-Carlo based approaches to global illumination including translucency and scattering. With the proposed techniques, users are able to interactively create convincing images from volumetric data whose visual quality goes far beyond traditional approaches. The optical properties in participating media are defined using the phase function. Many approximations to the physically based light transport applied for rendering natural phenomena such as clouds or smoke assume a rather homogenous phase function model. For rendering volumetric scans on the other hand different phase function models are required to account for both surface-like structures and fuzzy boundaries in the data. Using volume rendering techniques, artists who create medical visualization for science magazines may now work on tomographic scans directly, without the necessity to fall back to creating polygonal models of anatomical structures.

Prerequisites

Course participants should have a working knowledge in computer graphics, basic programming skills. They should be familiar with graphics hardware and shading languages. We will assume a basic knowledge regarding volume data as well as interactive volume rendering techniques.

Level of Difficulty

Intendet Audience

The course targets the steadily growing number of developers who create specialized implementations of volume rendering techniques on state-of-the-art graphics hardware, regardless of whether they are working in visual arts or scientific visualization.

Slides & Tutorial Notes

Here you can download the tutorial notes . 

Markus Hadwiger: Introduction and Basics

• Application Areas for Volume Rendering
• Benefits and Drawbacks of Ray-Casting
• GPU-based Volume Ray-Casting
• Space Leaping and Early Ray Termination
• Memory Management
• Multiresolution LOD and Adaptive sampling

Timo Ropinski: Light Interaction

• Light Transport and Illumination Models
• Local Volume Illumination
• Specular Reflections through Ray-Tracing
• Soft vs. Hard Shadows
• Semi-Transparent Shadows with Deep Shadow Maps
• Simulation of Color Bleeding

Patric Ljung: Ambient Occlusion

• Ambient Occlusion for Isosurfaces
• Local Ambient Occlusion (DVR)
• Dynamic Ambient Occlusion (DVR)

Christof Rezk-Salama: Scattering

• Monte-Carlo Integration
• Single versus Multiple Scattering
• Translucency
• Monte-Carlo Scattering
• First-order Multiple Scattering
• Scattering with Deep Shadow Maps

Instructors Background

Markus Hadwiger

Markus Hadwiger is a senior researcher at the VRVis Research Center in Vienna, Austria. He received his Ph.D. in computer science from the Vienna University of Technology in 2004, and has been a researcher at VRVis since 2000, working in the Basic Research on Visualization group and the Medical Visualization group (since 2004). He has been involved in several courses and tutorials about volume rendering and visualization at ACM SIGGRAPH, IEEE Visualization, and Eurographics. He is a co-author of the book Real-Time Volume Graphics published by A K Peters.

Patric Ljung

Patric Ljung joined in 2007 Siemens Corporate Research in Princeton, NJ, where he works as a Research Scientist in the Imaging Architectures group. He received 2006 his PhD in Scientific Visualization from Linköping University, Sweden and graduated with honors in 2000 his MS in Information Technology from Linköping University. Between 1989 and 1995 he worked as a software engineer with embedded and telecom systems involving software architectures, graphical user interfaces, voice-mail systems, communication protocols, network and interprocess communication, compilers.

Dr. Ljung has published several papers in international conferences and journals including IEEE Visualization, Eurographics conferences, IEEE TVCG and others, on volume rendering of large medical data sets, GPU-based ray-casting of multiresolution data sets. One important
focus area has been Virtual Autopsies for forensic pathology. His current research interest is in advanced illumination and shading techniques, software architectures for extensible graphics, and management and rendering of large medical data sets.

Christof Rezk-Salama

Christof Rezk-Salama has received a PhD from the University of Erlangen-Nuremberg as a scholarship holder of the graduate college 3D Image Analysis and Synthesis. He has worked as a research engineer for the R&D department of Siemens Medical Solutions. Since October 2003 he is working as an assistant professor at the Computer Graphics Group of the University of Siegen, Germany.

The results of his research have been presented at international conferences, including ACM SIGGRAPH, IEEE Visualization, Eurographics, MICCAI and Graphics Hardware. He is regularly holding lectures, courses and seminars on computer graphics, scientific visualization, character animation and graphics programming.

He has gained practical experience in applying computer graphics to several scientific projects in medicine, geology and archaeology. Christof Rezk-Salama has released the award winning open-source project OpenQVis and is a co-author of the book Real-Time
Volume Graphics.

Timo Ropinski

Timo Ropinski is a postdoctoral researcher working in the field of medical volume visualization. After receiving his PhD in 2004 from the University of Münster, he became a project leader within the collaborative research center SFB 656, a cooperation between researchers from medicine, mathematics, chemistry, physics and computer science. His research is focused on interactive aspects in medical volume visualization with the goal to make these techniques more accessible. He is regularly holding lectures and seminars on computer graphics and scientific visualization, and is the initiator of the Voreen open source project, in which a flexible volume rendering framework is developed. The results of his scientific work have been published in various international conferences including Eurographics, IEEE Visualization, IEEE VR, VMV and others.

Links

Book on Real-Time Volume Graphics: www.real-time-volume-graphics.org

Volume Graphics Course at SIGGRAPH 2004: www.vrvis.at/via/resources/course-volgraphics-2004/

Volumeshop: www.volumeshop.org

Voreen - Volume Rendering Engine: www.voreen.org