Doctor's Theses (authored and supervised):
"Real-Time Mono- and Multi-Volume Rendering of Large Medical Datasets on Standard PC Hardware";
Supervisor, Reviewer: E. Gröller;
Institut für Computergraphik und Algorithmen,
Direct Volume Visualization is an efficient technique to explore complex structures within volumetric data. Its main advantage, compared to standard 3D surface rendering, is the ability to perform semitransparent rendering in order to provide more information about spatial relationships of different structures. Semitransparent rendering requires to process a huge amount of data. The size of volumetric data is rapidly increasing, on the one hand due to the boost of processing power in the past years, and on the other hand due to improved capabilities of newer acquisition devices. This large data presents a challenge to current rendering architectures and techniques. The enormous data sizes introduce a growing demand for interactive 3D visualization. Conventional slicing methods already reach their limit of usability due to the enormous amount of slices. 3D visualization is more and more explored as an attractive alternative additional method for examinations of large medical data to support the necessary 2D examination. Within this dissertation a set of approaches to handle and render large volumetric data is developed, enabling significant performance improvements due to a much better utilization of the CPUs processing power and available memory bandwidth. At first, highly efficient approaches for addressing and processing of a cache efficient memory layout for volumetric data are presented. These approaches serve as a base for a full-blown high-quality raycasting system, capable of handling large data up to 3GB, a limitation imposed by the virtual address space of current consumer operating systems. The core acceleration techniques of this system are a refined caching scheme for gradient estimation in conjunction with a hybrid skipping and removal of transparent regions to reduce the amount of data to be processed. This system is extended so that efficient processing of multiple large data sets is possible. An acceleration technique for direct volume rendering of scenes, composed of multiple volumetric objects, is developed; it is based on the distinction between regions of intersection, which need costly multi-volume processing, and regions containing only one volumetric object, which can be efficiently processed. Furthermore, V-Objects, a concept of modeling scenes consisting of multiple volumetric objects, are presented. It is demonstrated that the concept of V-Objects in combination with direct volume rendering, is a promising technique for visualizing medical data and can provide advanced means to explore and investigate data. In the second part of the dissertation, an alternative to grid-based volume graphics is presented: Vots, a point-based representation of volumetric data. It is a novel primitive for volumetric data modeling, processing, and rendering. A new paradigm is presented by moving the data representation from a discrete representation to an implicit one.
Created from the Publication Database of the Vienna University of Technology.