VisSym99: Joint Eurographics - IEEE TCVG Symposium on Visualization

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https://diglib.eg.org/handle/10.2312/406

Link to Springer Online Library: http://link.springer.com/book/10.1007/978-3-7091-6803-5
available here: Eurographics version of papers

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Visualization of Grinding Processes
(Springer and The Eurographics Association, 1999) Fiege, Markus; Scheuermann, Gerik; Münchhofen, Michael; Hagen, Hans; Gröller, E., Löffelmann, H., Ribarsky, W.
In grinding technology, the application ofsupcrabrasivcs and increasing demands for higher productivity and higher quality require an appropriate selection of optimum set-up parameters. An efficient way to determine and test these parameters is modeling and simulating the grinding process. A visualization of the results can support the choice of the parameters and increase the knowledge of the complex grinding process. This paper describes a web-based visualization tool on the basis of a kinematic simulation. The tool allows the visualization of the surface of an already ground workpiece as well as the changing shape of the workpiece during the grinding process. Two methods for the visualization of the grinding-objects are implemented. One method describes the scene with the Virtual Reality Modeling Language, the other one uses a renderer to create the images.
VIVENDI - A Virtual Endoscopy System for Virtual Medicine
(Springer and The Eurographics Association, 1999) Bartz, Dirk; Skalej, Martin; Gröller, E., Löffelmann, H., Ribarsky, W.
Virtual Medicine is an emerging and challenging field in Computer Graphics. Numerous visualization methods are used to model and render data of different modalities. In this paper, we present a new endoscopy system for virtual medicine. The main purpose of this system is to provide support for the planning of complicated endoscopic interventions inside of the ventricular system of the human brain. Although, our current focus is on ventricle endoscopy, this system is applicable to other areas as well. In order to achieve interactive framerates on workstations with medium graphics performance, we apply an efficient implementation of a basic algorithm for general visibility queries.
Real-Time Maximum Intensity Projection
(Springer and The Eurographics Association, 1999) Mroz, Lukas; König, Andreas; Gröller, Eduard; Gröller, E., Löffelmann, H., Ribarsky, W.
Maximum Intensity Projection (MIP) is a volume rendering technique which is used to extract high-intensity structures from volumetric data. At each pixel the highest data value encountered along the corresponding viewing ray is determined. MIP is commonly used to extract vascular structures from medical MRI data sets (angiography). The usual way to compensate for the loss of spatial and occlusion information in MIP images is to view the data from different view points by rotating them. As the generation of MIP is usually non-interactive, this is done by calculating multiple images offline and playing them back as an animation. In this paper a new algorithm is proposed which is capable of interactively generating Maximum Intensity Projection images using parallel projection and templates. Voxels of the data set which will never contribute to a MIP due to their neighborhood are removed during a preprocessing step. The remaining voxels are stored in a way which guarantees optimal cache coherency regardless of the viewing direction. For use on low-end hardware, a preview-mode is included which renders only more significant parts of the volume during user interaction. Furthermore we demonstrate the usability of our data structure for extensions of the MIP technique like MIP with depth-shading and Local Maximum Intensity Projection (LMIP).
Visualization by Examples: Mapping Data to Visual Representations using Few Correspondences
(Springer and The Eurographics Association, 1999) Alexa, Marc; Müller, Wolfgang; Gröller, E., Löffelmann, H., Ribarsky, W.
In this paper we propose a new approach for the generation of visual scales for the visualization of scalar and multivariate data. Based on the specification of only a few correspondences between the data set and elements of a space of visual representations complex visualization mappings are produced. The foundation of this approach is the introduction of a multidimcnsional space of visual representations. The mapping between these spaces can he defined by approximating or satisfying the user defined relations between data values and visual atributes.
A Comparison of Error Indicators for Multilevel Visualization on Nested Grids
(Springer and The Eurographics Association, 1999) Gerstner, Thomas; Rumpf, Martin; Weikard, Ulrich; Gröller, E., Löffelmann, H., Ribarsky, W.
Multiresolution visualization methods have recently become an indispensable ingredient of real time interactive post processing. Here local error indicators serve as criteria where to refine the data representation on the physical domain. In this article we give an overview on different types of error measurement on nested grids and compare them for selected applications in 2D as well as in 3D. Furthermore, it is pointed out that a certain saturation of the considered error indicator plays an important role in multilevel visualization and can he reused for the evaluation of data bounds in hierarchical searching or for a multilevel backface culling of isosurfaces.
VISSION: An Object Oriented Dataflow System for Simulation and Visualization
(Springer and The Eurographics Association, 1999) Telea, Alexandru; Wijk, Jarke J. van; Gröller, E., Löffelmann, H., Ribarsky, W.
Scientific visualization and simulation speciification and monitoring are sometimes addressed by object-oriented environments. Even though object orientation powerfully and elegantly models many application domains, integration of 00 libraries in such systems remains a difficult task. The elegance and simplicity of object orientation is often lost in the integration phase, so combining 00 and dataflow concepts is usually limited. We propose a system for visualization and simulation with a generic object-oriented way to simulation design, control and interactivity, which merges 00 and dataflow modelling in a single abstraction. Advantages of the proposed system over similar tools are presented and illustrated by a comprehensive set of examples.
Geodesic Flow on Polyhedral Surfaces
(Springer and The Eurographics Association, 1999) Polthier, Konrad; Schmies, Markus; Gröller, E., Löffelmann, H., Ribarsky, W.
On a curved surface the front of a point wave evolves in concentric circles which start to overlap and branch after a certain time. This evolution is described by the geodesic flow and helps us to understand the geometry of surfaces. In this paper we compute the evolution of distance circles on polyhedral surfaces and develop a method to visualize the set of circles, their overlapping, branching, and their temporal evolution simultaneously. We consider the evolution as an interfering wave on the surface, and extend isometric texture maps to efficiently handle the branching and overlapping of the wave.
A Methodology for Comparing Direct Volume Rendering Algorithms Using a Projection-Based Data Level Approach
(Springer and The Eurographics Association, 1999) Kim, Kwansik; Pang, Alex; Gröller, E., Löffelmann, H., Ribarsky, W.
Identifying and visualizing uncertainty together with the data is a well recognized problem. One of the culprits that introduce uncertainty in the visualization pipeline is the visualization algorithm itself. Uncertainties introduced in this way usually arise from approximations and manifest themselves as artifacts in the resulting images. In this paper, we focus on comparing different direct volume rendering (DVR) algorithms and their artifacts as a result of DVR algorithm selections and their associated parameter settings. We present a new data level comparison methodology that uses differences in intermediate rendering information. In particular, we extend the traditional image level comparison techniques to include data level comparison techniques. In image level comparisons, quantized pixel values are the starting point for comparison measurements. In contrast, data level comparison techniques have the advantage of accessing and evaluating the intermediate 3D information during the rendering process. Our data level approach overcomes limitations of image level approaches and provide capabilities to compare application dependent details as well as general rendering qualities. One of the key challenges with our data level comparison approach is finding a common base for comparing the rich variety of DVR algorithms. In this paper, we present how a projection algorithm can be used as a base for comparing other DVR algorithms. In addition, a set of projection-based metrics are derived to quantify the comparison measurements among DVR algorithms. The results presented in this paper complement our earlier findings where a ray-based approach was used as the base for comparing other DVR algorithms.
Visualization of Molecules with Positional Uncertainty
(Springer and The Eurographics Association, 1999) Rheingans, Penny; Joshi, Shrikant; Gröller, E., Löffelmann, H., Ribarsky, W.
Designing new and better chemotherapeutic wmpounds requires an understanding of the mechanism by which the drugs exert their biological effects. This involves consideration of the geometry of the active site, determination of the geometry of the drug, and analysis of the fit between them. This problem of dr ug-suhstrate fit . often called the docking problem, can he greatly in fluenced by uncertainty in the position of drug side chains. Tradit ional molecular graphics techniques fail to capture the dist ribution oflikely atom positions. This paper describes a range of tedmiques for showing atom positions as probability distributions that more completely describe parameters which determine fit.
Where Weather Meets the Eye - A Case Study on a Wide Range of Meteorological Visualizations for Diverse Audiences
(Springer and The Eurographics Association, 1999) Haase, H.; Bock, M.; Hergenröther, E.; Knöpfle, C.; Koppert, H.-J.; Schröder, F.; Trembilski, A.; Weidenhausen, J.; Gröller, E., Löffelmann, H., Ribarsky, W.
Sophisticated visualisation enables experts as well as lay persons to extract knowledge from complex data. This is particularly true for visualising the massive amounts of data involved in meteorological observations and simulations. These are of interest to scientists, to forecasters, and to the general public. The paper presents and discusses a range of solutions for meteorlogical visualisation. Topics covered include systems for the production of TV weather forecasts, for the analysis of simulation output by experts, for personalised weather information in the Web, and for meteorological visualisation using Virtual Studio and Augmented Reality technology.
New Approaches for Particle Tracing on Sparse Grids
(Springer and The Eurographics Association, 1999) Teitzel, Christian; Ertl, Thomas; Gröller, E., Löffelmann, H., Ribarsky, W.
Flow visualization tools based on particle methods continue to be an important utility of flow simulation. Additionally, sparse grids are of increasing interest in numerical simulations. In [14] we presented the advontages of particle tracing on uniform sparse grids. Here we present and compare two different approaches to accelerate particle tracing on sparse grids. Furthermore, a new approach is presented in order to perform particle tracing on curvilinear sparse grids. The method for curvilinear sparse grids consists of a modified Stencil Walk algorithm and especially adapted routines to compute, store, and handle the required Jacobians. The accelerating approaches are on the on hand an adaptive method, where an error criterion is used to skip basis functions with minor contribution coefficients, and on the other hand the so-called combination technique, which uses a specific selection of small full grids to emulate sparse grids.
Fast Volume Rotation using Binary Shear-Warp Factorization
(Springer and The Eurographics Association, 1999) Csebfalvi, Balazs; Gröller, E., Löffelmann, H., Ribarsky, W.
This paper presents a fast volume rotation technique based on binary shear-warp factorization. Unlike many acceleration algorithms this method does not trade image quality for speed and does not require any specialized hardware either. In order to skip precisciy the empty regions along the rays to be evaluated a binary volume is generated indicating the locations of the transparent cells. This mask is rotated by an incremental binary shear transformation, executing bitwisc boolean operations on integers storing the bits of the binary volume. The ray casting is accelerated using the transformed mask and an appropriate lookup-table technique for finding the first non-transparent cell along each ray.
On Simulated Annealing and the Construction of Linear Spline Approximations for Scattered Data
(Springer and The Eurographics Association, 1999) Kreylos, Oliver; Hamann, Bernd; Gröller, E., Löffelmann, H., Ribarsky, W.
We describe a method to create optimal linear spline approximations to arbitrary functions of one or two variables, given as scattered data without known connectivity.We start with an initial approximation consisting of a fixed number of vertices and improve this approximation by choosing different vertices, governed by a simulated annealing algorithm. In the case of one variable, the approximation is defined by line segments; in the case of two variables, the vertices are connected to define a Delaunay triangulation of the selected subset of sites in the plane. In a second version of this algorithm, specifically designed for the bivariate case, we choose vertex sets and also change the triangulation to achieve both optimal vertex placement and optimal triangulation. We then create a hierarchy of linear spline approximations, each one being a superset of all lower-resolution ones.
2D Vector Field Visualization Using Furlike Texture
(Springer and The Eurographics Association, 1999) Khouas, Leila; Odet, Christophe; Friboulet, Denis; Gröller, E., Löffelmann, H., Ribarsky, W.
This paper presents a new technique for 2D vector field visualization. Our approach is based on the use of a furlike texture. For this purpose, we have first developed a texture model that allows two dimensional synthesis of 3D furlike texture. The technique is based on a non stationary two dimensional Autoregressive synthesis (2D AR). The texture generator allows local control of orientation and length of the synthesized texture (the orientation and length of filaments). This texture model is then used to represent 2D vector fields. We can use orientation, length, density and color attributes of our furlike texture to visualize local orientation and magnitude of a 2D vector field. The visual representations produced are satisfying since complete information about local orientation is easily perceived. We will show that the technique can also produce LIC-like texture. In addition, due to the AR formulation, the obtained technique is computationally efficient.
Parallel Multipipe Rendering for Very Large Isosurface Visualization
(Springer and The Eurographics Association, 1999) Udeshi, Tushar; Hansen, Charles D.; Gröller, E., Löffelmann, H., Ribarsky, W.
In exploratory scientific visualization, isosurfaces are typi- cally created with an explicit polygonal representation for the surface using a technique such as Marching Cubes. For even moderate data sets, Marchching Cubes can generate an extraordinary number of poly- gons, which take time to construct, and to render. To address the ren- dering bottleneck, we have developed a multipipe strategy for parallel rendering using a combination of CPUs and parallel graphics adaptors. The multipipe system uses multiple graphics adapters in parallel, the so called SGI Onyx2 Reality Monster. In this paper, we discuss the issues of using the multiple pipes in a Sort-Last fashion which out performs a single graphics adaptor for a surprisingly low number of polygons.
Interactive Direct Volume Rendering of Time-Varying Data
(Springer and The Eurographics Association, 1999) Clyne, John; Dennis, John M.; Gröller, E., Löffelmann, H., Ribarsky, W.
Previous efforts aimed at improving direct volume rendering performance have focused largely on time-invariant, 3D data. Little work has been done in the area of interactive direct volume rendering of timevarying data, such as is commonly found in Computational Fluid Dynamics (CFD) simulations. Until recently, the additional costs imposed by time-varying data have made consideration of interactive direct volume rendering impracticaL. We present a volume rendering system based on a parallel implementation of the Shear-Warp Factorization algorithm that is capable of rendering time-varying 128 3 data at interactive speeds.
Efficiently Rendering Large Volume Data Using Texture Mapping Hardware
(Springer and The Eurographics Association, 1999) Tong, Xin; Wang, Wenping; Tsang, Waiwan; Tang, Zesheng; Gröller, E., Löffelmann, H., Ribarsky, W.
Volume rendering with texture mapping hardware is a fast volume rendering method available on high-end workstations. However, limited texture memory often prevents the method from being used to render large volume data efficiently. In this paper, we propose a new approach to fast rendering of large volume data with texture mapping hardware. Based on a new volume-loading pipeline, the volume data is preprocessed in such a way that only the volume data that contains object voxels are loaded into texture memory and resampled for rendering. Moreover, if classification threshold is changed, our algorithm classifies and processes the raw volume data accordingly nearly in real time. Our tests show that about 40% to 60% rendering time is saved in our method for large volume data.
Exploring Instationary Fluid Flows by Interactive Volume Movies
(Springer and The Eurographics Association, 1999) Glau, Thomas; Gröller, E., Löffelmann, H., Ribarsky, W.
Volume rendering offers the unique ability to represent inner object data and to realize enclosed structures ""at first glance"". Unlike software-based methods, the use of more and more available specialpurpose hardware allows volume rendering at interactive frame rates - a crucial criterion for acceptance in industrial applications,e,g. CFD analysis, Careful optimizations and the exclusive use of hardware-accelerated data manipulation facilities even enable volume rendered movies supporting real time interactivity. This article presents the most important features and implementation issues of an OpenInventor-based stereoscopic, VR-featured volume rendering system for instationary datasets.
Visualization of Global Flow Structures Using Multiple Levels of Topology
(Springer and The Eurographics Association, 1999) Leeuw, Wim de; Liere, Robert van; Gröller, E., Löffelmann, H., Ribarsky, W.
The technique for visualizing topological information in fluid flows is well known. However, when the technique is used in complex and information rich data sets, the result will be a cluttered image which is difficult to interpet. This paper presents a technique for the visualization of multi-level topology in flow data sets. It provides the user with a mechanism to visualize the topology without excessive cluttering while maintaining the global structure of the flow.
Parallel Ray Casting of Visible Human on Distributed Memory Architectures
(Springer and The Eurographics Association, 1999) Bajaj, Chandrajit; Ihm, Insung; Koo, Gee-bum; Park, Sanghun; Gröller, E., Löffelmann, H., Ribarsky, W.
This paper proposes a new parallel ray-casting scheme for very large volume data on distributed-memory architectures. Our method, based on data compression, attempts to enhance the speedup of parallel rendering by quickly reconstructing data from local memory rather than expensively fetching them from remote memory spaces. Furthermore, it takes the advantages of both object-order and image-order traversal algorithms: It exploits object-space and image-space coherence, respectively, by traversing a min-max octrce block-wise and using a runtime quadtree which is maintained dynamically against pixels' opacity values. Our compression-based parallel volume rendering scheme minimizes conmUnications between processing elements during rendering, hence is also very appropriate for more practical distributed systems, such as dusters of PCs and/or workstations, in which data conmlUnications between processors are regarded as quite costly. We report experimental results on a Cray T3E for the Visible Man dataset.

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