EuroVis05: Joint Eurographics - IEEE VGTC Symposium on Visualization

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https://diglib.eg.org/handle/10.2312/400

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Analysis and Visualization of 3-C PIV Images from HART II using Image Processing Methods
(The Eurographics Association, 2005) Ebling, Julia; Scheuermann, Gerik; Wall, Berend G. van der; Ken Brodlie and David Duke and Ken Joy
In this paper, three-component particle image velocimetry (3-C PIV) measurements within the wake of a helicopter rotor from the HART II test are analyzed. These PIV-images are quite a challenge as the noise due to the measurement method and the inherent turbulence of the flow can not be distinguished. Furthermore, features are often hidden by a mean flow, which is influenced by vortices and therefore not easy to determine. The authors present some image processing methods adapted to these vector fields for the computation of position, size, and direction of the vortices in this data. These methods are quite robust in terms of noise and independent of any mean flow and therefore appropriate for this analysis. The results of the analysis allow a more descriptive and intuitive visualization of the vortices.
ArcTrees: Visualizing Relations in Hierarchical Data
(The Eurographics Association, 2005) Neumann, Petra; Schlechtweg, Dr. Stefan; Carpendale, Sheelagh; Ken Brodlie and David Duke and Ken Joy
In this paper we present, ARCTREES, a novel way of visualizing hierarchical and non-hierarchical relations within one interactive visualization. Such a visualization is challenging because it must display hierarchical information in a way that the user can keep his or her mental map of the data set and include relational information without causing misinterpretation. We propose a hierarchical view derived from traditional Treemaps and augment this view with an arc diagram to depict relations. In addition, we present interaction methods that allow the exploration of the data set using Focus+Context techniques for navigation. The development was motivated by a need for understanding relations in structured documents but it is also useful in many other application domains such as project management and calendars.
BioBrowser: A Framework for Fast Protein Visualization
(The Eurographics Association, 2005) Halm, Andreas; Offen, Lars; Fellner, Dieter W.; Ken Brodlie and David Duke and Ken Joy
This paper presents a protein visualization system called BioBrowser, which provides high quality images at interactive frame rates for molecules of extreme size and complexity. This is achieved by a shift in the tessellation approach: triangle meshes are not produced a priori on a 'just-in-case' basis. Instead, tessellation happens 'justin- time' given a certain camera position, image size and interaction demand. Thus, our approach is based on multiresolution meshes and on new extensions of graphics hardware. The paper shows how to reduce geometric data by using subdivision surfaces for ribbon structures and molecular surfaces and by using billboards instead of spheres consisting of triangles. It also shows how to use fragment shaders to create a three dimensional appearance and realistic sphere intersections. The combination of these approaches leads to an image quality not yet seen in interactive visualization environments for molecules of that size/complexity. All the above methods are combined to gain a high performance configurable visualization system on standard hardware.
Combining Silhouettes, Surface, and Volume Rendering for Surgery Education and Planning
(The Eurographics Association, 2005) Tietjen, Christian; Isenberg, Tobias; Preim, Bernhard; Ken Brodlie and David Duke and Ken Joy
We introduce a flexible combination of volume, surface, and line rendering.We employ object-based edge detection because this allows a flexible parametrization of the generated lines. Our techniques were developed mainly for medical applications using segmented patient-individual volume datasets. In addition, we present an evaluation of the generated visualizations with 8 medical professionals and 25 laypersons. Integration of lines in conventional rendering turned out to be appropriate.
Dense Geometric Flow Visualization
(The Eurographics Association, 2005) Park, Sung W.; Budge, Brian; Linsen, Lars; Hamann, Bernd; Joy, Kenneth I.; Ken Brodlie and David Duke and Ken Joy
We present a flow visualization technique based on rendering geometry in a dense, uniform distribution. Flow is integrated using particle advection. By adopting ideas from texture-based techniques and taking advantage of parallelism and programmability of contemporary graphics hardware, we generate streamlines and pathlines addressing both steady and unsteady flow. Pipelining is used to manage seeding, advection, and expiration of streamlines/ pathlines with constant lifetime. We achieve high numerical accuracy by enforcing short particle lifetimes and employing a fourth-order integration method. The occlusion problem inherent to dense volumetric representations is addressed by applying multi-dimensional transfer functions (MDTFs), restricting particle attenuation to regions of certain physical behavior, or features. Geometry is rendered in graphics hardware using techniques such as depth sorting, illumination, haloing, flow orientation, and depth-based color attenuation to enhance visual perception. We achieve dense geometric three-dimensional flow visualization with interactive frame rates.
Discovering High-level Parameters for Visualization Design
(The Eurographics Association, 2005) Bhagavatula, Srinivas; Rheingans, Penny; Jardins, Marie des; Ken Brodlie and David Duke and Ken Joy
In most graphics and visualization applications, the effects of the mapping parameters on the output domain are multidimensional, non-linear and discontinuous. The complexity of such mapping often makes it difficult for a user to manually explore and manipulate the design parameter space to produce the desired output. Computer assistance is therefore useful in setting the mapping parameter values to generate desired outputs. Existing systems rely on exploring the entire input parameter space, which can be time and resource-intensive, particularly if the number of input parameters is large. We introduce a new approach to handling a large number of mapping parameters more efficiently. The basis for our approach is the identification of a small and effective set of highlevel parameters that can be associated directly with the characteristics of the outputs. Users will have a better understanding of this small set of high-level parameters and can easily modify their values interactively to produce the desired outputs. We demonstrate this technique in manipulating mapping parameters for a non-photorealistic volume rendering application.
Dynamically Modelling Interaction
(The Eurographics Association, 2005) May, Jon; Ken Brodlie and David Duke and Ken Joy
Technological advances are increasing the use of dynamic or changing displays, in many forms of interface. The increasing amount of information held on the Internet and in private government and commercial databases also requires more innovative approaches to retrieval and browsing than existing text-based search engines can provide.
Extending and Simplifying Transfer Function Design in Medical Volume Rendering Using Local Histograms
(The Eurographics Association, 2005) Lundström, Claes; Ljung, Patric; Ynnerman, Anders; Ken Brodlie and David Duke and Ken Joy
Direct Volume Rendering (DVR) is known to be of diagnostic value in the analysis of medical data sets. However, its deployment in everyday clinical use has so far been limited. Two major challenges are that the current methods for Transfer Function (TF) construction are too complex and that the tissue separation abilities of the TF need to be extended. In this paper we propose the use of histogram analysis in local neighborhoods to address both these conflicting problems. To reduce TF construction difficulty, we introduce Partial Range Histograms in an automatic tissue detection scheme, which in connection with Adaptive Trapezoids enable efficient TF design. To separate tissues with overlapping intensity ranges, we propose a fuzzy classification based on local histograms as a second TF dimension. This increases the power of the TF, while retaining intuitive presentation and interaction.
Galilean Invariant Extraction and Iconic Representation of Vortex Core Lines
(The Eurographics Association, 2005) Sahner, Jan; Weinkauf, Tino; Hege, Hans-Christian; Ken Brodlie and David Duke and Ken Joy
While vortex region quantities are Galilean invariant, most methods for extracting vortex cores depend on the frame of reference. We present an approach to extracting vortex core lines independently of the frame of reference by extracting ridge and valley lines of Galilean invariant vortex region quantities. We discuss a generalization of this concept leading to higher dimensional features. For the visualization of extracted line features we use an iconic representation indicating their scale and extent. We apply our approach to datasets from numerical simulations and experimental measurements.
GVis: A Scalable Visualization Framework for Genomic Data
(The Eurographics Association, 2005) Hong, Jin; Jeong, Dong Hyun; Shaw, Chris D; Ribarsky, William; Borodovsky, Mark; Song, Chang; Ken Brodlie and David Duke and Ken Joy
This paper describes a framework we have developed for the visual analysis of large-scale phylogeny hierarchies populated with the genomic data of various organisms. This framework allows the user to quickly browse the phylogeny hierarchy of organisms from the highest level down to the level of an individual genome for the desired organism of interest. Based on this framework, the user can initiate gene-finding and gene-matching analyses and view the resulting annotated coding potential graphs in the same multi-scale visualization framework, permitting correlative analysis and further investigation. This paper introduces our framework and describes the data structures and algorithms that support it.
Hardware-Accelerated Glyphs for Mono- and Dipoles in Molecular Dynamics Visualization
(The Eurographics Association, 2005) Reina, Guido; Ertl, Thomas; Ken Brodlie and David Duke and Ken Joy
We present a novel visualization method for mono- and dipolar molecular simulations from thermodynamics that takes advantage of modern graphics hardware to interactively render specifically tailored glyphs. Our approach allows domain experts to visualize the results of molecular dynamics simulations with a higher number of particles than before and furthermore offers much better visual quality. We achieve this by transferring only visualization parameters to the GPU and by generating implicit surfaces directly in the fragment program. As a result, we can render up to 500.000 glyphs with about 10 fps displaying all the simulation results as geometrical properties that resemble the classical abstract representation used in this research area. Thus we enable researchers to visually assess the results of simulations of greater scale than before. We believe that the proposed method can be generalized to create other kinds of parametrized surfaces directly on graphics hardware to overcome the bandwidth bottleneck that exists between CPU and GPU.
High-Quality Rendering of Compressed Volume Data Formats
(The Eurographics Association, 2005) Fout, Nathaniel; Akiba, Hiroshi; Ma, Kwan-Liu; Lefohn, Aaron E.; Kniss, Joe; Ken Brodlie and David Duke and Ken Joy
Rendering directly from packed or compressed volume data formats using graphics hardware has advantages in terms of memory consumption and bandwidth, but results in lower-quality images due to the prohibitive cost of performing interpolation and gradient-based shading on the reconstructed data. The problem with the existing method lies in its close coupling of decompression and interpolation. We demonstrate that deferred filtering overcomes this problem by using a two-pass decompression and rendering strategy. With this method interpolation and gradient calculations are very efficient, allowing high quality rendering directly from packed or compressed volume data. We evaluate the cost of creating interpolated, gradient-shaded renderings using traditional on-the-fly decompression and deferred filtering, and show that deferred filtering can provide up to twenty times speed-up for high quality rendering.
High-Quality Volume Rendering with Resampling in the Frequency Domain
(The Eurographics Association, 2005) Artner, Martin; Möller, Torsten; Viola, Ivan; Gröller, Meister E.; Ken Brodlie and David Duke and Ken Joy
This work introduces a volume rendering technique that is conceptually based on the shear-warp factorization. We propose to perform the shear transformation in the frequency domain. Unlike the standard shear-warp algorithm, we allow for arbitrary sampling distances along the viewing rays, independent from the view direction. The accurate scaling of the volume slices is achieved by using the zero padding interpolation property. Finally, a high quality gradient estimation scheme is presented which uses the derivative theorem of the Fourier transform. Experimental results show that the presented method outperforms established algorithms in the quality of the produced images. If the data is sampled above the Nyquist rate the presented method is capable of a perfect reconstruction of the original function.
The i-Disc - A Tool To Visualize and Explore Topic Maps
(The Eurographics Association, 2005) Hofmann, Tobias; Wendler, Hendrik; Froehlich, Bernd; Ken Brodlie and David Duke and Ken Joy
We present the i-Disc, a tool to interactively visualize and explore medium sized topic maps. Topic maps contain two basic structures: the topic hierarchy and the associations between topics. Our system presents the topic hierarchy in a radial planar layout by encoding different hierarchy levels as separate rings. Associations are displayed on demand as three-dimensional arcs across the topic landscape. By separating these two topic map structures into different spatial dimensions, we untangle the often complex topic map graph. A perspective rendering of our layout generates a natural focus and context display. Our elementary circular design allows quick perception of the overall topic map structure while interactive navigation and exploration provide access to details on demand. The tool is implemented as a client-server application and integrates seamlessly into existing web based environments.
Illustrative Context-Preserving Volume Rendering
(The Eurographics Association, 2005) Bruckner, Stefan; Grimm, Sören; Kanitsar, Armin; Gröller, M. Eduard; Ken Brodlie and David Duke and Ken Joy
In volume rendering it is very difficult to simultaneously visualize interior and exterior structures while preserving clear shape cues. Very transparent transfer functions produce cluttered images with many overlapping structures, while clipping techniques completely remove possibly important context information. In this paper we present a new model for volume rendering, inspired by techniques from illustration that provides a means of interactively inspecting the interior of a volumetric data set in a feature-driven way which retains context information. The context-preserving volume rendering model uses a function of shading intensity, gradient magnitude, distance to the eye point, and previously accumulated opacity to selectively reduce the opacity in less important data regions. It is controlled by two user-specified parameters. This new method represents an alternative to conventional clipping techniques, shares their easy and intuitive user control, but does not suffer from the drawback of missing context information.
Interactive Methods for Exploring Particle Simulation Data
(The Eurographics Association, 2005) Co, Christopher S.; Friedman, Alex; Grote, David P.; Vay, Jean-Luc; Bethel, E. Wes; Joy, Kenneth I.; Ken Brodlie and David Duke and Ken Joy
In this work, we visualize high-dimensional particle simulation data using a suite of scatterplot-based visualizations coupled with interactive selection tools. We use traditional 2D and 3D projection scatterplots as well as a novel oriented-disk rendering style to convey various information about the data. Interactive selection tools allow physicists to manually classify "interesting" sets of particles that are highlighted across multiple, linked views of the data. The power of our application is the ability to correspond new visual representations of the simulation data with traditional, well understood visualizations. This approach supports the interactive exploration of the high-dimensional space while promoting discovery of new particle behavior.
Interactive rendering of massive terrains on PC clusters
(The Eurographics Association, 2005) Gouranton, V.; Madougou, Souley; Melin, Emmanuel; Nortet, Cyril; Ken Brodlie and David Duke and Ken Joy
We describe a parallel framework for interactive smooth rendering of massive terrains. We define a parallelization scheme for level of detail algorithms in cluster-based environments. The scheme relies on modern PC clusters capabilities to address the scalability issue of level of detail algorithms. To achieve this, we propose an eficient tile-based data partitioning method that allows both reducing load imbalance and solving the well-known border problem. At runtime level of detail computations are performed in parallel on cluster nodes. A hierarchical view frustum culling combined to a compression mechanism harnessing the frame-to-frame coherence are used to drastically reduce the inter-tasks communication overhead. We take into account level of detail algorithms visual quality issue by providing geomorphing and texturing supports. We are able to interactively and smoothly render terrains composed of hundreds of millions to billions of polygons on a cluster of 8 PCs.
Interactive Visualization for Neck-Dissection Planning
(The Eurographics Association, 2005) Krüger, Arno; Tietjen, Christian; Hintze, Jana; Preim, Bernhard; Hertel, Ilka; Strauß, Gero; Ken Brodlie and David Duke and Ken Joy
In this paper, we present visualization techniques for neck dissection planning. These interventions are carried out to remove lymph node metastasis in the neck region. 3d visualization is intended to explore and to quantify anatomic and pathologic structures and thus support decisions concerning the surgical strategy. For this purpose we developed and combined visualization and interaction techniques such as cutaway views, silhouettes and colorcoded distances. In addition, a standardized procedure for processing and visualization of the patient data is presented.
Isosurface Extraction Using Fixed-Sized Buckets
(The Eurographics Association, 2005) Waters, Kenneth W.; Co, Christopher S.; Joy, Kenneth I.; Ken Brodlie and David Duke and Ken Joy
We present a simple and output optimal algorithm for accelerated isosurface extraction from volumetric data sets. Output optimal extraction algorithms perform an amount of work dominated by the size of the (output) isosurface rather than the size of the (input) data set. While several optimal methods have been proposed to accelerate isosurface extraction, these algorithms are relatively complicated to implement or require quantized values as input. Our method is based on a straightforward array data structure that only requires an auxiliary sorting routine for construction. The method works equally well for floating point data as it does for quantized data sets. We demonstrate how the data structure can exploit coherence between isosurfaces by performing searches incrementally. We show results for real application data validating the method's optimality.
Localized Flow Analysis of 2D and 3D Vector Fields
(The Eurographics Association, 2005) Wiebel, Alexander; Garth, Christoph; Scheuermann, Gerik; Ken Brodlie and David Duke and Ken Joy
In this paper we present an approach to the analysis of the contribution of a small subregion in a dataset to the global flow. To this purpose, we subtract the potential flow that is induced by the boundary of the sub-domain from the original flow. Since the potential flow is free of both divergence and rotation, the localized flow field retains the original features. In contrast to similar approaches, by making explicit use of the boundary flow of the subregion, we manage to isolate the region-specific flow that contains exactly the local contribution of the considered subdomain to the global flow. In the remainder of the paper, we describe an implementation on unstructured grids in both two and three dimensions. We discuss the application of several widely used feature extraction methods on the localized flow, with an emphasis on topological schemes.

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