VisSym01: Joint Eurographics - IEEE TCVG Symposium on Visualization

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https://diglib.eg.org/handle/10.2312/404

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Comparative Visualization of Instabilities in Crash-Worthiness Simulations
(The Eurographics Association, 2001) Sommer, Ove; Ertl, Thomas; David S. Ebert and Jean M. Favre and Ronald Peikert
Since crash-worthiness simulations get more and more important as part of the car development process in order to reduce the cost of development, enhance the product quality, and minimize the time-to-market, the reliability of the simulation results plays a decisive role concerning their significance. Recently the simulation departments of several automotive companies started investigating the quantity and reason for deviations during a number of simulation runs on the same input model. In this case study we discuss different measurements for instability and present a texture-based visualization method which allows the engineers to efficiently explore the simulation results by interactively hiding finite element structures with nearly constant crash performance. Furthermore, we describe those parts of our prototype which use a CORBA layer for providing the same view on a set of simulation results and allowing the visual comparison by using the marker functionality.
A Hardware-Assisted Visibility-Ordering Algorithm With Applications To Volume Rendering
(The Eurographics Association, 2001) Krishnan, Shankar; Silva, Cláudio T.; Wei, Bin; David S. Ebert and Jean M. Favre and Ronald Peikert
We propose a hardware-assisted visibility ordering algorithm. From a given viewpoint, a (back-to-front) visibility ordering of a set of objects is a partial order on the objects such that if object A obstructs object B, then B precedes A in the ordering. Such orderings are useful because they are the building blocks of other rendering algorithms such as direct volume rendering of unstructured grids. The traditional way to compute the visibility order is to build a set of visibility relations (e.g., B < p A), and then run a topological sort on the set of relations to actually get the partial ordering. Our technique instead works by assigning a layer number to each primitive, which directly determines the visibility ordering. Objects that have the same layer number are independent, and have no obstruction between each other. We use a simple technique which exploits a combination of the z- and stencil buffers to compute the layer number of each primitive. One application of our technique is to obtain a fast unstructured volume rendering algorithm. In this paper, we present our technique and its implementation in OpenGL. We also discuss its performance and some optimizations on some recent graphics hardware architectures.
Subdivision Surfaces for Scattered-data Approximation
(The Eurographics Association, 2001) Bertram, Martin; Hagen, Hans; David S. Ebert and Jean M. Favre and Ronald Peikert
We propose a modified Loop subdivision surface scheme for the approximation of scattered data in the plane. Starting with a triangulated set of scattered data with associated function values, our scheme applies linear, stationary subdivision rules resulting in a hierarchy of triangulations that converge rapidly to a smooth limit surface. The novelty of our scheme is that it applies subdivision only to the ordinates of control points, whereas the triangulated mesh in the plane is fixed. Our subdivision scheme defines locally supported, bivariate basis functions and provides multiple levels of approximation with triangles. We use our subdivision scheme for terrain modeling.
Nonlinear Diffusion in Graphics Hardware
(The Eurographics Association, 2001) Rumpf, M.; Strzodka, R.; David S. Ebert and Jean M. Favre and Ronald Peikert
Multiscale methods have proved to be successful tools in image denoising, edge enhancement and shape recovery. They are based on the numerical solution of a nonlinear diffusion problem where a noisy or damaged image which has to be smoothed or restorated is considered as initial data. Here a novel approach is presented which will soon be capable to ensure real time performance of these methods. It is based on an implementation of a corresponding finite element scheme in texture hardware of modern graphics engines. The method regards vectors as textures and represents linear algebra operations as texture processing operations. Thus, the resulting performance can profit from the superior bandwidth and the build in parallelism of the graphics hardware. Here the concept of this approach is introduced and perspectives are outlined picking up the basic Perona Malik model on 2D images.
A Case Study in Multi-Sensory Investigation of Geoscientific Data
(The Eurographics Association, 2001) Harding, Chris; Kakadiaris, Ioannis A.; Casey, John F.; Loftin, R. Bowen; David S. Ebert and Jean M. Favre and Ronald Peikert
In this paper, we report our ongoing research into multi-sensory investigation of geoscientific data. Our Geoscientific Data Investigation System (GDIS) integrates three-dimensional, interactive computer graphics, touch (haptics) and real-time sonification into a multi-sensory Virtual Environment. GDIS has been used to investigate geological structures on the high-resolution bathymetry data from the Mid-Atlantic Ridge. Haptic force feedback was used to precisely digitize line features on three-dimensional morphology and to feel surface properties via varying friction settings; additional, overlapping data can be perceived via sound (sonification). We also report on the results of a psycho-acoustic study about the absolute recognition of sound signals, and on the actual feedback that we have received from a number of geoscientists during a recent major geoscience conference.
Case Study: Visualization and Information Retrieval Techniques for Network Intrusion Detection
(The Eurographics Association, 2001) Atkison, Travis; Pensy, Kathleen; Nicholas, Charles; Ebert, David; Atkison, Rebekah; Morris, Chris; David S. Ebert and Jean M. Favre and Ronald Peikert
We describe our efforts to analyze network intrusion detection data using information retrieval and visualization tools. By regarding Telnet sessions as documents, which may or may not include attacks, a session that contains a certain type of attack can be used as a query, allowing us to search the data for other instances of that same type of attack. The use of information visualization techniques allows us to quickly and clearly find the attacks and also find similar, potentially new types of attacks.
Multiresolution Maximum Intensity Volume Rendering by Morphological Pyramids
(The Eurographics Association, 2001) Roerdink, Jos B.T.M.; David S. Ebert and Jean M. Favre and Ronald Peikert
We propose a multiresolution representation for maximum intensity projection (MIP) volume rendering, based on morphological pyramids which allow progressive refinement and have the property of perfect reconstruction. The pyramidal analysis and synthesis operators are composed of morphological erosion and dilation, combined with dyadic downsampling for analysis and dyadic upsampling for synthesis. The structure of the multiresolution MIP representation is very similar to wavelet splatting, the main differences being that (i) linear summation of voxel values is replaced by maximum computation, and (ii) linear wavelet filters are replaced by (nonlinear) morphological filters.
Extraction of Crack-free Isosurfaces from Adaptive Mesh Refinement Data
(The Eurographics Association, 2001) Weber, Gunther H.; Kreylos, Oliver; Ligocki, Terry J.; Shalf, John M.; Hagen, Hans; Hamann, Bernd; Joy, Kenneth I.; David S. Ebert and Jean M. Favre and Ronald Peikert
Adaptive mesh refinement (AMR) is a numerical simulation technique used in computational fluid dynamics (CFD). It permits the efficient simulation of phenomena characterized by substantially varying scales in complexity of local behavior of certain variables. By using a set of nested grids at different resolutions, AMR combines the simplicity of structured rectilinear grids with the possibility to adapt to local changes in complexity and spatial resolution. Hierarchical representations of scientific data pose challenges when isosurfaces are extracted. Cracks can arise at the boundaries between regions represented at different resolutions. We present a method for the extraction of isosurfaces from AMR data that avoids cracks at the boundaries between levels of different resolution.
Salient Representation of Volume Data
(The Eurographics Association, 2001) Hladuvka, Jiri; König, Andreas; Gröller, Eduard; David S. Ebert and Jean M. Favre and Ronald Peikert
We introduce a novel method for identification of objects of interest in volume data. Our approach conveys the information contained in two essentially different concepts, the object s boundaries and the narrow solid structures, in an easy and uniform way. The second order derivative operators in directions reaching minimal response are employed for this task. To show the superior performance of our method, we provide a comparison with its main competitor surface extraction from areas of maximal gradient magnitude. We show that our approach provides the possibility to represent volume data by a subset of a nominal size.
Visualization of directed associations in e-commerce transaction data
(The Eurographics Association, 2001) Hao, Ming C.; Dayal, Umeshwar; Hsu, Meichun; Sprenger, Thomas; Gross, Markus H.; David S. Ebert and Jean M. Favre and Ronald Peikert
Many real-world e-commerce applications require the mining of large volumes of transaction data to extract marketing and sales information. This paper describes the Directed Association Visualization (DAV) system that visually associates product affinities and relationships for large volumes of e-commerce transaction data. DAV maps transaction data items and their relationships to vertices, edges, and positions on a visual spherical surface. DAV encompasses several innovative techniques (1) items are positioned according to their associations to show the strength of their relationships; (2) edges with arrows are used to represent the implication directions; (3) a mass-spring engine is integrated into a visual data mining platform to provide a self-organized graph. We have applied this system successfully to market basket analysis and e-customer profiling Internet applications.
DDDiver: 3D Interactive Visualization of Entity Relationships
(The Eurographics Association, 2001) Coomans, Marc; Timmermans, Harry; David S. Ebert and Jean M. Favre and Ronald Peikert
In this paper we present DDDiver, a tool for the interactive visualization and editing of Object-Oriented databases. It was developed to visualize and manipulate large loosely-structured data sets with multiple relation types. This makes the tool especially useful in application areas that involve product data models, design information systems, and semantic networks. DDDiver can visualize such relational data sets in a 3d graph. The layout mechanism used for the graph is not based on a deterministic mathematical algorithm, but on the distinction between a number of relation kinds, and on user interaction. The intuitiveness and quickness of the visualization tool was further improved by adding animated visual feedback effects.
Visualization of Generalized Voronoi Diagrams
(The Eurographics Association, 2001) Telea, Alexandru; Wijk, Jarke J. van; David S. Ebert and Jean M. Favre and Ronald Peikert
Voronoi diagrams are an important data structure in computer science. However well studied mathematically, understanding such diagrams for different metrics, orders, and site shapes is a complex task. We propose a new method to visualize k-order diagrams and give an efficient adaptive implementation for this method. The algorithm is easy to customize for different metrics and site shapes. Its real-time performance makes it suitable for interactive planning and analysis of complex Voronoi configurations in 2D.We illustrate the method for different combinations of metrics and site shapes.
Vector and Tensor Field Topology Simplification on Irregular Grids
(The Eurographics Association, 2001) Tricoche, Xavier; Scheuermann, Gerik; Hagen, Hans; Clauss, Stefan; David S. Ebert and Jean M. Favre and Ronald Peikert
Topology-based visualization of planar turbulent flows results in visual clutter due to the presence of numerous features of very small scale. In this paper, we attack this problem with a topology simplification method for vector and tensor fields defined on irregular grids. This is the generalization of previous work dealing with structured grids. The method works for all interpolation schemes.
Volume Rendering Data with Uncertainty Information
(The Eurographics Association, 2001) Djurcilov, Suzana; Kim, Kwansik; Lermusiaux, Pierre F. J.; Pang, Alex; David S. Ebert and Jean M. Favre and Ronald Peikert
This paper explores two general methods for incorporating volumetric uncertainty information in direct volume rendering. The goal is to produce volume rendered images that depict regions of high (or low) uncertainty in the data. The first method involves incorporating the uncertainty information directly into the volume rendering equation. The second method involves post-processing information of volume rendered images to composite uncertainty information. We present some initial findings on what mappings provide qualitatively satisfactory results and what mappings do not. Results are considered satisfactory if the user can identify regions of high or low uncertainty in the rendered image. We also discuss the advantages and disadvantages of both approaches.
Space-Efficient Boundary Representation of Volumetric Objects
(The Eurographics Association, 2001) Mroz, Lukas; Hauser, Helwig; David S. Ebert and Jean M. Favre and Ronald Peikert
In this paper we present a compression technique for efficiently representing boundary objects from volumetric data-sets. Exploiting spatial coherency within object contours, we are able to reduce the size of the volumetric boundary down to the size of just a few images. Allowing for direct volume rendering of the down-scaled data in addition to compression ratios up to 250:1, interactive volume visualization becomes possible, even over the Internet and on low-end hardware.
Automotive Soiling Simulation Based On Massive Particle Tracing
(The Eurographics Association, 2001) Roettger, Stefan; Schulz, Martin; Bartelheimer, Wolf; Ertl, Thomas; David S. Ebert and Jean M. Favre and Ronald Peikert
In the automotive industry Lattice-Boltzmann type flow solvers like PowerFlow from Exa Corporation are becoming increasingly important. In contrast to the traditional finite volume approach PowerFlow utilizes a hierachical cartesian grid for flow simulation. In this case study we show how to take advantage of these hierarchical grids in order to extend an existing Lattice-Boltzmann CFD environment with an automotive soiling simulation system. To achieve this, we chose to constantly generate a huge number of massive particles in user manipulable particle emitters. The process of tracing these particles step by step thus creates evolving particle streams, which can be displayed interactively by our visualization system. Each particle is created with stochastically varying diameter, specific mass and initial velocity, whereas already existing particles may decay because of aging, when leaving the simulation domain or when colliding with the vehicle s surface. On the one hand the display of these animated particles is a very natural and intuitive way to explore a CFD data set. On the other hand animated massive particles can be easily utilized for driving an automotive soiling simulation just by coloring the particles hit points on the vehicle s surface.
Preserving the Mental Map using Foresighted Layout
(The Eurographics Association, 2001) Diel, Stepahn; Görg, Carsten; Kerren, Andreas; David S. Ebert and Jean M. Favre and Ronald Peikert
First we introduce the concept of graph animations as a sequence of evolving graphs and a generic algorithm which computes a Foresighted Layout for dynamically drawing these graphs while preserving the mental map. The algorithm is generic in the sense that it takes a static graph drawing algorithm as a parameter. In other words, trees can be animated with a static tree layouter, graphs with a static Sugiyama-style layouter or a spring embedder, etc. Second we discuss applications of Foresighted Layout in algorithm animation and visualization of navigation behaviour.
Fast Multiresolution Extraction of Multiple Transparent Isosurfaces
(The Eurographics Association, 2001) Gerstner, Thomas; David S. Ebert and Jean M. Favre and Ronald Peikert
In this paper, we present a multiresolution algorithm which is capable to render multiple transparent isosurfaces under real time constraints. To this end, the underlying 3D data set is covered with a hierarchical tetrahedral grid. The multiresolution extraction algorithm is then based on an adaptive traversal of the tetrahedral grid with the help of error indicators. The display of transparent isosurfaces using alpha blending requires a back to front rendering of the isosurface triangles. This is achieved by a hierarchical sorting procedure of the tetrahedra and the hierarchical computation of data gradients. We will also comment on the automated selection of suitable isovalues for visualization applications.
Improved visualization in virtual colonoscopy using image-based rendering
(The Eurographics Association, 2001) Serlie, Iwo; Vos, Frans; Gelder, Rogier van; Stoker, Jaap; Truyen, Roel; Gerritsen, Frans; Nio, Yung; Post, Frits; David S. Ebert and Jean M. Favre and Ronald Peikert
Virtual colonoscopy (VC) is a patient-friendly alternative for colorectal endoscopic examination. We explore visualization aspects of VC such as surface in view, navigation and communication of a diagnosis. A series of unfolded cubes presents an animated full 360-degree omnidirectional field-of-view to the physician, to facilitate thorough and rapid inspection. For communication between physicians a tool has been designed that uses image-based rendering. Clinical evaluation has shown a reduction in inspection time from 19 minutes to 7 minutes without loss of sensitivity. With current virtual colonoscopy using a 2-sided view only 94% of the surface is available for exploration. In our approach the surface in view is increased to potentially 100%. Thus, the entire colon can be explored with better confidence that no regions are missed.
I/O-Conscious Volume Rendering
(The Eurographics Association, 2001) Yang, Chuan-Kai; Chiueh, Tzi-cker; David S. Ebert and Jean M. Favre and Ronald Peikert
Most existing volume rendering algorithms assume that data sets are memory-resident and thus ignore the performance overhead of disk I/O. While this assumption may be true for high-performance graphics machines, it does not hold for most desktop personal workstations. To minimize the end-to-end volume rendering time, this work re-examines implementation strategies of the ray casting algorithm, taking into account both computation and I/O overheads. Specifically, we developed a data-driven execution model for ray casting that achieves the maximum overlap between rendering computation and disk I/O. Together with other performance optimizations, on a 300-MHz Pentium-II machine, without directional shading, our implementation is able to render a 128x128 greyscale image from a 128x128x128 data set with an average end-to-end delay of 1 second, which is very close to the memory-resident rendering time. With a little modification, this work can also be extended to do out-of-core visualization as well.

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