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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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.
Advances in Quality Control of Intraoperative Radiotherapy
(Springer and The Eurographics Association, 1999) Walter, Stefan; Straßmann, Gerd; Schmitt, Marco; Gröller, E., Löffelmann, H., Ribarsky, W.
Intraoperative radiotherapy is the kind of radiotherapy where the remains of a surgically not completely removed tumour are irradiated at the open situ of the patient. The current main drawback of this radiotherapy is the insufficient documentation of the applied radiation and the lack of a possibility for an individual treatment planning. This work presents a system that is a conmlon development of Fraunhofer IGD, Städtische Klinik Offenbach and MedCom GmbH which offers a possibility for supervision of the placement of the irradiation flabs through interactive navigation in eT data acquired from the patient, the creation of a documentation of the applied isodose as well as the possibility for an individual treatment planning.
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.
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.
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.
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.
Analysis and Visualization of the Brain Shift Phenomenon in Neurosurgery
(Springer and The Eurographics Association, 1999) Lürig, C.; Hastreiter, P.; Nimsky, C.; Ertl, T.; Gröller, E., Löffelmann, H., Ribarsky, W.
In this paper we present a method for analyzing the brain shift. The brain shift is a brain deformation phenomenon, that occurs during surgical operations on the opened head. This deformation makes navigation within the brain very difficult for the surgeon, as preoperative magnetic resonance images invalidate very quickly after the beginning of the operation. Up to now not enough is known about this deformation phenomenon in order to come up with solutions for corrective action. The aim of the tool which is presented here is to prepare ground for a better understanding by visualizing the deformation between two 3D brain data sets, where one has been taken preoperatively and the second one during the operation after the brain shift has occured. We propose a new method for the modeling of the deformation by means of efficient distance determination of two deformable surface approximations. Color coding and semi-transparent overlay of the surfaces provides qualitative and quantitative information about the brain shift. The provided insight may lead to a prediction method in future.
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.
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.
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.
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.
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.
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.
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 Client-side Approach towards Platform Independent Molecular Visualization over the World Wide Web
(Springer and The Eurographics Association, 1999) Bender, Michael; Hagen, Hans; Seck, Axel; Gröller, E., Löffelmann, H., Ribarsky, W.
A web-based, entirely platform independent Molecular Visualization System has been developed using state of the Internet programming techniques. This system offers the visualization of various molecular models, molecular surfaces and molecular properties which can be displayed at the same time . The system itself has been developed using the Java programming language, which alIows flexible and platform independent use, perfect integration with the World Wide Web and due to its object-oriented structure easy extension and maintenance. All necessary calculations, e.g. the calculation of a Richards' Contact Surface or an lsosurface, take place on the client's side exploiting the computational power of modern desktop workstations and personal computers.
Efficient Ray Intersection for Visualization and Navigation of Global Terrain using Spheroidal Height-Augmented Quadtrees
(Springer and The Eurographics Association, 1999) Wartell, Zachary; Ribarsky, William; Hodges, Larry; Gröller, E., Löffelmann, H., Ribarsky, W.
We present an algorithm for efficiently computing ray intersections with multi-resolution global terrain partitioned by spheroidal height-augmented quadtrees. While previous methods support terrain defined on a Cartesian coordinate system, our methods support terrain defined on a two-parameter ellipsoidal coordinate system. This curvilinear system is necessary for an accurate model of global terrain. Supporting multi-resolution terrain and quadtrees on this curvilinear coordinate system raises a surprising number of complications.We describe the complex- ities and present solutions. The final algorithm is suited for interactive terrain selection, collision detection and simple LOS (line-of-site) queries on global terrain.

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