DevLan/vispubs huggingface dataset:
CVSgrab: Mining the History of Large Software Projects
Authors: Lucian Voinea, Alexandru C. Telea
Published at EuroVis, 2006

Many software projects use Software Configuration Management systems to support their development process. Such systems accumulate in time large amounts of information useful for process accounting and auditing. We study how software developers can get insight in this information in order to understand the project context and the product artifacts. To this end, we propose several new techniques for visual mining of project evolution. Central to our approach is a file-based evolution visualization, where each project is shown as a set of horizontal stripes depicting files along the time axis. We propose several mechanisms for interactively building layouts in this display, and for correlating the evolution with the results of various software metrics. We demonstrate the usefulness of our approach on real- life data sets.
D2VR: High-Quality Volume Rendering of Projection-based Volumetric Data
Authors: Peter Rautek, Balázs Csébfalvi, Sören Grimm, Stefan Bruckner, M. Eduard Gröller
Published at EuroVis, 2006

Volume rendering techniques are conventionally classified as either direct or indirect methods. Indirect methods require to transform the initial volumetric model into an intermediate geometrical model in order to efficiently visualize it. In contrast, direct volume rendering (DVR) methods can directly process the volumetric data. Modern CT scanners usually provide data as a set of samples on a rectilinear grid, which is computed from the measured projections by discrete tomographic reconstruction. Therefore the rectilinear grid can already be considered as an intermediate volume representation. In this paper we introduce direct direct volume rendering (D2VR). D2VR does not require a rectilinear grid, since it is based on an immediate processing of the measured projections. Arbitrary samples for ray casting are reconstructed from the projections by using the Filtered Back-Projection algorithm. Our method removes a lossy resampling step from the classical volume rendering pipeline. It provides much higher accuracy than traditional grid-based resampling techniques do. Furthermore we also present a novel high-quality gradient estimation scheme, which is also based on the Filtered Back-Projection algorithm.
Data Reconstruction and Visualization Techniques for Forensic Pathology
Authors: Alexander Ehlert, Zein Salah, Dirk Bartz
Published at EuroVis, 2006

Forensic pathology is largely concerned with the determination of the cause and manner of deaths after accidents, or other circumstances in criminal investigations. A major task in that process is the documentation of surface injuries, which is traditionally done by drawing sketches, photography, or more recently by photogrammetry to generate a three-dimensional digital lesion cartography of the body surface.

In this paper, we describe a semi-automatic processing pipeline how data from 3D photogrammetry is combined and used to generate a visual surface representation of accident victims. In that course, a number of steps are performed to provide a high-quality interactive, point-based visualization of the acquired data, which can be used in a more routine way than previous forensic surface methods.
Direct Isosurface Extraction from Scattered Volume Data
Authors: Paul Rosenthal, Lars Linsen
Published at EuroVis, 2006

Isosurface extraction is a standard visualization method for scalar volume data and has been subject to research for decades. Nevertheless, to our knowledge, no isosurface extraction method exists that directly extracts surfaces from scattered volume data without 3D mesh generation or reconstruction over a structured grid. We propose a method based on spatial domain partitioning using a kd-tree and an indexing scheme for efficient neighbor search. Our approach consists of a geometry extraction and a rendering step. The geometry extraction step computes points on the isosurface by linearly interpolating between neighboring pairs of samples. The neighbor information is retrieved by partitioning the 3D domain into cells using a kd-tree. The cells are merely described by their index and bitwise index operations allow for a fast determination of potential neighbors. We use an angle criterion to select appropriate neighbors from the small set of candidates. The output of the geometry step is a point cloud representation of the isosurface. The final rendering step uses point-based rendering techniques to visualize the point cloud.

Our direct isosurface extraction algorithm for scattered volume data produces results of quality close to the results from standard isosurface extraction algorithms for gridded volume data (like marching cubes). In comparison to 3D mesh generation algorithms (like Delaunay tetrahedrization), our algorithm is about one order of magnitude faster for the examples used in this paper.
Efficient Surface Reconstruction from Noisy Data using Regularized Membrane Potentials
Authors: Andrei C. Jalba, Jos B. T. M. Roerdink
Published at EuroVis, 2006

We present a novel, physically-motivated method for surface reconstruction that can recover smooth surfaces from noisy and sparse data sets, without using orientation information. A new volumetric technique based on regularized-membrane potentials for aggregating the input sample points is introduced, which manages improved noise tolerability and outlier removal, without sacrificing much with respect to detail (feature) recovery. In this method, sample points are first aggregated on a volumetric grid. A labeling algorithm that relies on intrinsic properties of the smooth scalar field emerging after aggregation is used to classify grid points as exterior or interior to the surface. We also introduce a mesh-smoothing paradigm based on a mass-spring system, enhanced with a bending-energy minimizing term to ensure that the final triangulated surface is smoother than piecewise linear. The method compares favorably with respect to previous approaches in terms of speed and flexibility.
Enhanced Visualizations of Thermographic Data in Process Industry
Authors: Stefan Seipel, Ann-Kristin Forsberg, Daniel Wesslén
Published at EuroVis, 2006

In this paper, we describe an improved method for visualization of thermographic data in the paper and pulp process industry. We present an application that allows process operators to freely choose how absolute temperatures and time varying changes of thermographic scans should be mapped to colors and/or 3D shapes. Of the possible combinations, we selected two different forms of 3D visualizations and an existing conventional 2D map visualization. We then evaluated these visualization forms with regard to their effectiveness in experimental field studies. The field tests were carried out to measure the operators' performance in early detection of insulation damages on lime kilns. The results we obtained from the study show that the two new forms of 3D visualization lead to a reduction of the detection times by about two-thirds and one-third, respectively, when compared to the conventional 2D map representation. Since lime kiln monitoring is based on the rather generic method of continuous thermographic imaging, we suggest that these results also hold for the control and surveillance of other processes.
Enhancing Slice-based Visualizations of Medical Volume Data
Authors: Christian Tietjen, Björn Meyer, Stefan Schlechtweg, Bernhard Preim, Ilka Hertel, Gero Strauß
Published at EuroVis, 2006

Slice-based visualizations of CT and MRI data are frequently used for diagnosis, intervention planning and intraoperative navigation since they allow a precise analysis and localization. We present new techniques to enhance the visualization of cross sectional medical image data. Our work is focussed on intervention planning and intraoperative navigation. We address the following problems of slice-based visualization in these areas: the lack of a graphical overview on the positions of anatomic structures, the localization of a target structure and the display of safety zones around pathologic structures. To improve the overview, we introduce LIFTCHARTs, attached as vertical bars to a slice-based visualization. For localizing target structures, we introduce halos. These techniques restrict the occlusion of the original data to a minimum and avoid any modification of the original data. To demonstrate the usability of these visualization techniques, we show two application scenarios in which the techniques come into operation.
Evaluating the Effectiveness of Tree Visualization Systems for Knowledge Discovery
Authors: Yue Wang, Soon Tee Teoh, Kwan-Liu Ma
Published at EuroVis, 2006

User studies, evaluations, and comparisons of tree visualization systems have so far focused on questions that can readily be answered by simple, automated queries without needing visualization. Studies are lacking on the actual use of tree visualization in discovering intrinsic, hidden, non-trivial and potentially valuable knowledge. We have thus formulated a set of tree exploration tasks not previously considered and have performed user studies and analysis to determine how visualization helps users to perform these tasks. In our study, we evaluated three systems: RINGS (a node-link representation), Treemap (a containment representation), and Windows Explorer. Our findings suggest a few ways that tree visualization helps users to perceive different aspects of hierarchical structured information. We then explain how these visual representations are able to trigger human perception to make these discoveries.
Fast Ray Traversal of Tetrahedral and Hexahedral Meshes for Direct Volume Rendering
Authors: Gerd Marmitt, Philipp Slusallek
Published at EuroVis, 2006

The importance of high-performance rendering of unstructured or curvilinear data sets has increased significantly, mainly due to its use in scientific simulations such as computational fluid dynamics and finite element computations. However, the unstructured nature of these data sets lead to rather slow implementations for ray tracing. The approaches discussed in this paper are fast and scalable towards realtime ray tracing applications.

We evaluate new algorithms for rendering tetrahedral and hexahedral meshes. In each algorithm, the first cell along a ray is found using common realtime ray tracing techniques. For traversing subsequent cells within the volume, Plucker coordinates as well as ray-bilinear patch intersection tests are used. Since the volume is rendered directly, all algorithms are applicable for isosurface rendering, maximum-intensity projection, and emissionabsorption models.
GPU-Accelerated Volume Splatting With Elliptical RBFs
Authors: Neophytos Neophytou, Klaus Mueller 0001, Kevin T. McDonnell, Wei Hong 0006, Xin Guan, Hong Qin, Arie E. Kaufman
Published at EuroVis, 2006

Radial Basis Functions (RBFs) have become a popular rendering primitive, both in surface and in volume rendering. This paper focuses on volume visualization, giving rise to 3D kernels. RBFs are especially convenient for the representation of scattered and irregularly distributed point samples, where the RBF kernel is used as a blending function for the space in between samples. Common representations employ radially symmetric RBFs, and various techniques have been introduced to render these, also with efficient implementations on programmable graphics hardware (GPUs). In this paper, we extend the existing work to more generalized, ellipsoidal RBF kernels, for the rendering of scattered volume data. We devise a post-shaded kernel-centric rendering approach, specifically designed to run efficiently on GPUs, and we demonstrate our renderer using datasets from subdivision volumes and computational science.
GPU-Based Hyperstreamlines for Diffusion Tensor Imaging
Authors: Guido Reina, Katrin Bidmon, Frank Enders, Peter Hastreiter, Thomas Ertl
Published at EuroVis, 2006

We propose a new approach for the visualization of hyperstreamlines, which offers potential for better scalability than the conventional polygon-based approach. Our method circumvents the bandwidth bottleneck between the CPU and GPU by transmitting a small set of parameters for each tube segment and generates the surface directly on the GPU using the classical sphere tracing approach. This reduces the load on the CPU that would otherwise need to provide a suitable level-of-detail representation of the scene, while offering even higher quality in the resulting surfaces since every fragment is traced individually. We demonstrate the effectiveness of this approach by comparing it to the performance and output of conventional visualization tools in the application area of diffusion tensor imaging of human brain MR scans.

The method presented here can also be utilized to generate other types of surfaces on the GPU that are too complex to handle with direct ray casting and can therefore be adapted for other applications.
GPUFLIC: Interactive and Accurate Dense Visualization of Unsteady Flows
Authors: Guo-Shi Li, Xavier Tricoche, Charles D. Hansen
Published at EuroVis, 2006

The paper presents an efficient and accurate implementation of Unsteady Flow LIC (UFLIC) on the Graphics Processing Unit (GPU). We obtain the same, high quality texture representation of unsteady two-dimensional flows as the original, time-consuming method but leverage the features of today's commodity hardware to achieve interactive frame rates. Despite a remarkable number of recent contributions in the field of texture-based visualization of time-dependent vector fields, the present paper is the first to provide a faithful implementation of that prominent technique fully supported by the graphics pipeline.
Hardware-accelerated Extraction and Rendering of Point Set Surfaces
Authors: Eduardo Tejada, Joao Paulo Gois, Luis Gustavo Nonato, Antônio Castelo Filho, Thomas Ertl
Published at EuroVis, 2006

Point-based models are gaining lately considerable attention as an alternative to traditional surface meshes. In this context, Point Set Surfaces (PSS) were proposed as a modeling and rendering method with important topological and approximation properties. However, ray-tracing PSS is computationally expensive. Therefore, we propose an interactive ray-tracing algorithm for PSS implemented completely on commodity graphics hardware. We also exploit the advantages of PSS to propose a novel technique for extracting surfaces directly from volumetric data. This technique is based on the well known predictor-corrector principle from the numerical methods for solving ordinary differential equations. Our technique provides good approximations to surfaces defined by a certain property in the volume, such as iso-surfaces or surfaces located at regions of high gradient magnitude. Also, local details of the surfaces could be manipulated by changing the local polynomial approximation and the smoothing parameters used. Furthermore, the surfaces generated are smooth and low frequency noise is naturally handled.
Improving the Quality of Multi-resolution Volume Rendering
Authors: Hamid Younesy, Torsten Möller, Hamish A. Carr
Published at EuroVis, 2006

We propose a novel method to improve the quality of multi-resolution visualizations. We reduce aliasing artifacts by approximating the data distribution with a Gaussian basis function at each level of detail for more accurate rendering at coarser levels of detail. We then show an efficient implementation of our novel Gaussian based approximation scheme and show its superiority using numerical tests and compelling renderings.
Integrated Visualization of Morphologic and Perfusion Data for the Analysis of Coronary Artery Disease
Authors: Steffen Oeltze, Anja Kuß, Frank Grothues, Anja Hennemuth, Bernhard Preim
Published at EuroVis, 2006

We present static and dynamic techniques to visualize perfusion data and to relate perfusion data to morphologic image data. In particular, we describe the integrated analysis of MRI myocardial perfusion data with CT coronary angiographies depicting the morphology. We refined the Bull's-Eye Plot, a wide-spread and accepted analysis tool in cardiac diagnosis, to show aggregated information of perfusion data at rest and under stress. The correlation between regions of the myocard with reduced perfusion and 3d renditions of the coronary vessels can be explored within a synchronized visualization of both. With our research, we attempt to improve the diagnosis of early stage coronary artery disease.
Integrating Dynamic Deformations into Interactive Volume Visualization
Authors: Tom Brunet, K. Evan Nowak, Michael Gleicher
Published at EuroVis, 2006

Non-linear geometric deformation (or warping) is a useful tool for working with volumes. Unfortunately, the computational expense of performing the resampling needed to implement volume deformation has precluded its use in interactive applications. In this paper, we show how non-linear deformations can be integrated into interactive volume visualization allowing for dynamic deformations to be used along with interactive viewing, exploration, and manipulation tools. We describe how hardware assisted volume rendering can be adapted to resample volume deformations, leveraging programmable shaders to compute deformations and the local coordinate transformations required for shading effects. We describe how volume interaction techniques, such as ray picking and plane slicing, can be used in concert with our deformation methods. Our methods extend to simultaneous display of multiple volumes enabling comparisons. We demonstrate dynamic volume deformation at interactive rates on commodity hardware for interactive deformation control, animated deformations, and volume widgets.
Knowledge-Based Out-of-Core Algorithms for Data Management in Visualization
Authors: David Chisnall, Min Chen 0001, Charles D. Hansen
Published at EuroVis, 2006

Data management is the very first issue in handling very large datasets. Many existing out-of-core algorithms used in visualization are closely coupled with application-specific logic. This paper presents two knowledgebased out-of-core prefetching algorithms that do not use hard-coded rendering-related logic. They acquire the knowledge of the access history and patterns dynamically, and adapt their prefetching strategies accordingly. We have compared the algorithms with a demand-based algorithm, as well as a more domain-specific out-of-core algorithm. We carried out our evaluation in conjunction with an example application where rendering multiple point sets in a volume scene graph put a great strain on the rendering algorithm in terms of memory management. Our results have shown that the knowledge-based approach offers a better cache-hit to disk-access trade-off. This work demonstrates that it is possible to build an out-of-core prefetching algorithm without depending on rendering-related application-specific logic. The knowledge based approach has the advantage of being generic, efficient, flexible and self-adaptive.
Lossless Geometry Compression for Steady-State and Time-Varying Irregular Grids
Authors: Dan Chen, Yi-Jen Chiang, Nasir D. Memon, Xiaolin Wu 0001
Published at EuroVis, 2006

In this paper we investigate the problem of lossless geometry compression of irregular-grid volume data represented as a tetrahedral mesh. We propose a novel lossless compression technique that effectively predicts, models, and encodes geometry data for both steady-state (i.e., with only a single time step) and time-varying datasets. Our geometry coder is truly lossless and also does not need any connectivity information. Moreover, it can be easily integrated with a class of the best existing connectivity compression techniques for tetrahedral meshes with a small amount of overhead information. We present experimental results which show that our technique achieves superior compression ratios, with reasonable encoding times and fast (linear) decoding times.
Multiresolution Interblock Interpolation in Direct Volume Rendering
Authors: Patric Ljung, Claes Lundström, Anders Ynnerman
Published at EuroVis, 2006

We present a direct interblock interpolation technique that enables direct volume rendering of blocked, multiresolution volumes. The proposed method smoothly interpolates between blocks of arbitrary block-wise level-of-detail (LOD) without sample replication or padding. This permits extreme changes in resolution across block boundaries and removes the interblock dependency for the LOD creation process. In addition the full data reduction from the LOD selection can be maintained throughout the rendering pipeline. Our rendering pipeline employs a flat block subdivision followed by a transfer function based adaptive LOD scheme. We demonstrate the effectiveness of our method by rendering volumes of the order of gigabytes using consumer graphics cards on desktop PC systems.
Natural Visualizations
Authors: Steve Haroz, Kwan-Liu Ma
Published at EuroVis, 2006

This paper demonstrates the prevalence of a shared characteristic between visualizations and images of nature. We have analyzed visualization competitions and user studies of visualizations and found that the more preferred, better performing visualizations exhibit more natural characteristics. Due to our brain being wired to perceive natural images [SO01], testing a visualization for properties similar to those of natural images can help show how well our brain is capable of absorbing the data. In turn, a metric that finds a visualization's similarity to a natural image may help determine the effectiveness of that visualization. We have found that the results of comparing the sizes and distribution of the objects in a visualization with those of natural standards strongly correlate to one's preference of that visualization.
Path Line Oriented Topology for Periodic 2D Time-Dependent Vector Fields
Authors: Kuangyu Shi, Holger Theisel, Tino Weinkauf, Helwig Hauser, Hans-Christian Hege, Hans-Peter Seidel
Published at EuroVis, 2006

This paper presents an approach to extracting a path line oriented topological segmentation for periodic 2D timedependent vector fields. Topological methods aiming in capturing the asymptotic behavior of path lines rarely exist because path lines are usually only defined over a fixed time-interval, making statements about their asymptotic behavior impossible. For the data class of periodic vector fields, this restriction does not apply any more. Our approach detects critical path lines as well as basins from which the path lines converge to the critical ones. We demonstrate our approach on a number of test data sets.
Perspective Isosurface and Direct Volume Rendering for Virtual Endoscopy Applications
Authors: Henning Scharsach, Markus Hadwiger, André Neubauer 0002, Stefan Wolfsberger, Katja Bühler
Published at EuroVis, 2006

Virtual endoscopy has proven to be a very powerful tool in endoscopic surgery. However, most virtual endoscopy systems are restricted to rendering isosurfaces or require segmentation in order to visualize additional objects behind occluding tissue. This paper presents a system for real-time perspective direct volume and isosurface rendering, which allows to simultaneously visualize both the interesting tissue and everything that is behind. Large volume data can be viewed seamlessly from inside or outside the volume without any pre-computation or segmentation. Our system uses a novel ray-casting pipeline for GPUs that has been optimized for the requirements of virtual endoscopy and also allows easy incorporation of auxiliary geometry, e.g., for displaying parts of the endoscopic device, pointers, or grid lines for orientation purposes. We present three main applications of this system and the underlying ray-casting algorithm. Although our ray-casting approach is of general applicability, we have specifically applied it to virtual colonoscopy, virtual angioscopy, and virtual pituitary surgery.