Chair: Arie Kaufman (Stony Brook University, USA)

Expanding the Universe – From Volume Rendering to
High-Dimensional Data Visualization
by Klaus Mueller, Computer Science Department, Stony Brook University and SUNY Korea

When I began my research career, volume rendering was a hot topic. It was invented in part because of great advances at another front – medical imaging. These emerging modalities, such as X-ray Computed Tomography, produced data that needed to be visualized in fully 3D and not just by surfaces. During my PhD years and after I was working in both domains – 3D volume reconstruction from projection data produced by CT and the visualization of these using volume rendering. Volume data were considered ‘big’ back then and their visualization ‘computationally expensive’. Fortunately, another great advance came along – the birth of commodity graphics hardware, now known as GPUs. First attempts to use these boards for volume rendering were largely hacks – albeit very creative ones. But eventually, driven by the strong market forces of computer games, both hardware and API of GPUs became very flexible and one could soon render even large volumes in amazing beauty, with complex special effects, and at interactive speeds. So where to go from here – increase data size, add more dimensions, make things more irregular? I decided to do it all and ventured into the dark universe of high-dimensional data. There, I soon was ‘cursed by high dimensionality’ and got lost in the maze of ‘redundant subspaces’. But eventually I ‘illuminated my path’ and hopefully that of others. On my journey I found that knowing volume rendering can be quite helpful for understanding some of the issues that arise in high-dimensional data visualization, for example, in sampling and rendering. In this talk I want to share my experiences and also present our software package ‘The ND-Scope‘ which features some of the practical outcomes of the research I have conducted along with my students in recent years.


Klaus Mueller received a PhD in computer science and an MS in Biomedical Engineering, both from The Ohio State University. He is currently a professor in the Computer Science Department at Stony Brook University and the chair of the Computer Science Department at SUNY Korea, the first US University on Korean soil. His current research interests are visual analytics, computer graphics, medical imaging, and high-performance computing, He won the US National Science Foundation CAREER award in 2001 and the SUNY Chancellor Award for Excellence in Scholarship and Creative Activity in 2011. Mueller has authored more than 160 peer-reviewed journal and conference papers, which have been cited more than 5,000 times. He is a frequent speaker at international conferences, has participated in numerous tutorials on various topics, and is currently the chair of the IEEE Technical Committee on Visualization and Computer Graphics. He was an associate editor of IEEE Transactions on Visualization and Computer Graphics and is a senior member of the IEEE. For more information, please see


Chair: Kwan-Liu Ma (University of California, Davis, USA)

Comparative Visualization [slides]
by Eduard Gröller, Vienna University of Technology

Visualization uses computer-supported, interactive, visual representations of (abstract) data to amplify cognition. In recent years data complexity and variability has increased considerably. This is due to new data sources as well as the availability of uncertainty, error and tolerance information. Instead of individual objects entire sets, collections, and ensembles are visually investigated. This raises the need for effective comparative visualization approaches. Visual data science and computational sciences provide vast amounts of digital variations of a phenomenon which can be explored through superposition, juxtaposition and explicit difference encoding. A few examples of comparative approaches coming from the various areas of visualization, i.e., scientific visualization, information visualization and visual analytics will be treated in more detail. Comparison and visualization techniques are helpful to carry out parameter studies for the special application area of non-destructive testing using 3D X-ray computed tomography (3DCT). We discuss multi-image views and an edge explorer for comparing and visualizing gray value slices and edges of several datasets simultaneously. Visual steering supports decision making in the presence of alternative scenarios. Multiple, related simulation runs are explored through branching operations. To account for uncertain knowledge about the input parameters, visual reasoning employs entire parameter distributions. This can lead to an uncertainty-aware exploration of (continuous) parameter spaces. VAICo, i.e., Visual Analysis for Image Comparison, depicts differences and similarities in large sets of images. It preserves contextual information, but also allows the user a detailed analysis of subtle variations. The approach identifies local changes and applies cluster analysis techniques to embed them in a hierarchy. The results of this comparison process are then presented in an interactive web application which enables users to rapidly explore the space of differences and drill-down on particular features. Given the amplified data variability, comparative visualization techniques are likely to gain in importance in the future. Research challenges, directions, and issues concerning this innovative area are sketched at the end of the talk.


Eduard Gröller ( is Professor at the Institute of Computer Graphics and Algorithms (ICGA), Vienna University of Technology. In 1993 he received his PhD from the same university. His research interests include computer graphics, visualization, and visual computing. He is heading the visualization group at ICGA. The group performs basic and applied research projects in all areas of visualization ( Dr. Gröller has given lecture series on visualization at various other universities (Tübingen, Graz, Praha, Bahia Blanca, Magdeburg, Bergen). He is a scientific proponent and key researcher of the VRVis research center ( The center performs applied research in visualization, rendering, and visual analysis. Dr. Gröller is adjunct professor of computer science at the University of Bergen, Norway (since 2005). He co-authored more than 220 scientific publications and acted as a reviewer for numerous conferences and journals in the field. He also has served and serves on various program and paper committees. Examples include Computers & Graphics, IEEE Transactions on Visualization and Graphics, EuroVis conference, IEEE Visualization conference, Eurographics conference. He has been paper co-chair of Volume Graphics 2005, IEEE Visualization 2005 and 2006, and Eurographics 2006. He has been co-chair of the VisSym 1999 symposium, the Eurographics 2011 conference, and the EuroVis 2012 conference. Dr. Gröller has been chief editor of the Journal Computer Graphics Forum ( in the period 2008-2011. He became a fellow of the Eurographics association in 2009. Dr. Gröller is head of the working group on computer graphics of the Austrian Computer Society and member of IEEE Computer Society, ACM (Association of Computing Machinery), GI (Gesellschaft für Informatik), OCG (Austrian Computer Society).