DevLan/vispubs huggingface dataset:
Eyegaze analysis of displays with combined 2D and 3D views
Authors: Melanie Tory, M. Stella Atkins, Arthur E. Kirkpatrick, Marios Nicolaou, Guang-Zhong Yang
Published at Vis, 2005

Displays combining both 2D and 3D views have been shown to support higher performance on certain visualization tasks. However, it is not clear how best to arrange a combination of 2D and 3D views spatially in a display. In this study, we analyzed the eyegaze strategies of participants using two arrangements of 2D and 3D views to estimate the relative position of objects in a 3D scene. Our results show that the 3D view was used significantly more often than individual 2D views in both displays, indicating the importance of the 3D view for successful task completion. However, viewing patterns were significantly different between the two displays: transitions through centrally-placed views were always more frequent, and users avoided saccades between views that were far apart. Although the change in viewing strategy did not result in significant performance differences, error analysis indicates that a 3D overview in the center may reduce the number of serious errors compared to a 3D overview placed off to the side.
Eyelet particle tracing - steady visualization of unsteady flow
Authors: Alexander Wiebel, Gerik Scheuermann
Published at Vis, 2005

It is a challenging task to visualize the behavior of time-dependent 3D vector fields. Most of the time an overview of unsteady fields is provided via animations, but, unfortunately, animations provide only transient impressions of momentary flow. In this paper we present two approaches to visualize time varying fields with fixed geometry. Path lines and streak lines represent such a steady visualization of unsteady vector fields, but because of occlusion and visual clutter it is useless to draw them all over the spatial domain. A selection is needed. We show how bundles of streak lines and path lines, running at different times through one point in space, like through an eyelet, yield an insightful visualization of flow structure ("eyelet lines"). To provide a more intuitive and appealing visualization we also explain how to construct a surface from these lines. As second approach, we use a simple measurement of local changes of a field over time to determine regions with strong changes. We visualize these regions with isosurfaces to give an overview of the activity in the dataset. Finally we use the regions as a guide for placing eyelets.
Farthest point seeding for efficient placement of streamlines
Authors: Abdelkrim Mebarki, Pierre Alliez, Olivier Devillers
Published at Vis, 2005

We propose a novel algorithm for placement of streamlines from two-dimensional steady vector or direction fields. Our method consists of placing one streamline at a time by numerical integration starting at the furthest away from all previously placed streamlines. Such a farthest point seeding strategy leads to high quality placements by favoring long streamlines, while retaining uniformity with the increasing density. Our greedy approach generates placements of comparable quality with respect to the optimization approach from Turk and Banks, while being 200 times faster. Simplicity, robustness as well as efficiency is achieved through the use of a Delaunay triangulation to model the streamlines, address proximity queries and determine the biggest voids by exploiting the empty circle property. Our method handles variable density and extends to multiresolution.
Fast and reproducible fiber bundle selection in DTI visualization
Authors: Jorik Blaas, Charl P. Botha, Bart Peters, Frans Vos, Frits H. Post
Published at Vis, 2005

Diffusion tensor imaging (DTI) is an MRI-based technique for quantifying water diffusion in living tissue. In the white matter of the brain, water diffuses more rapidly along the neuronal axons than in the perpendicular direction. By exploiting this phenomenon, DTI can be used to determine trajectories of fiber bundles, or neuronal connections between regions, in the brain. The resulting bundles can be visualized. However, the resulting visualizations can be complex and difficult to interpret. An effective approach is to pre-determine trajectories from a large number of positions throughout the white matter (full brain fiber tracking) and to offer facilities to aid the user in selecting fiber bundles of interest. Two factors are crucial for the use and acceptance of this technique in clinical studies: firstly, the selection of the bundles by brain experts should be interactive, supported by real-time visualization of the trajectories registered with anatomical MRI scans. Secondly, the fiber selections should be reproducible, so that different experts will achieve the same results. In this paper we present a practical technique for the interactive selection of fiber-bundles using multiple convex objects that is an order of magnitude faster than similar techniques published earlier. We also present the results of a clinical study with ten subjects that show that our selection approach is highly reproducible for fractional anisotropy (FA) calculated over the selected fiber bundles.
Fast visualization by shear-warp on quadratic super-spline models using wavelet data decompositions
Authors: Gregor Schlosser, Jürgen Hesser, Frank Zeilfelder, Christian Rössl, Reinhard Männer, Günther Nürnberger, Hans-Peter Seidel
Published at Vis, 2005

We develop the first approach Tor interactive volume visualization based on a sophisticated rendering method of shear-warp type, wavelet data encoding techniques, and a trivariate spline model, which has been introduced recently. As a first step of our algorithm, we apply standard wavelet expansions to represent and decimate the given gridded three-dimensional data. Based on this data encoding, we give a sophisticated version of the shear-warp based volume rendering method. Our new algorithm visits each voxel only once taking advantage of the particular data organization of octrees. In addition, the hierarchies of the data guide the local (re)construction of the quadratic super-spline models, which we apply as a pure visualization tool. The low total degree of the polynomial pieces allows to numerically approximate the volume rendering integral efficiently. Since the coefficients of the splines are almost immediately available from the given data, Bernstein-Bezier techniques can be fully employed in our algorithms. In this way, we demonstrate that these models can be successfully applied to full volume rendering of hierarchically organized data. Our computational results show that (even when hierarchical approximations are used) the new approach leads to almost artifact-free visualizations of high quality for complicated and noise-contaminated volume data sets, while the computational effort is considerable low, i.e. our current implementation yields 1-2 frames per second for parallel perspective rendering a 2563 volume data set (using simple opacity transfer functions) in a 5122 view-port.
Framework for visualizing higher-order basis functions
Authors: William J. Schroeder, François Bertel, Mathieu Malaterre, David C. Thompson 0001, Philippe P. Pébay, Robert M. O'Bara, Saurabh Tendulkar
Published at Vis, 2005

Techniques in numerical simulation such as the finite element method depend on basis functions for approximating the geometry and variation of the solution over discrete regions of a domain. Existing visualization systems can visualize these basis functions if they are linear, or for a small set of simple non-linear bases. However, newer numerical approaches often use basis functions of elevated and mixed order or complex form; hence existing visualization systems cannot directly process them. In this paper we describe an approach that supports automatic, adaptive tessellation of general basis functions using a flexible and extensible software architecture in conjunction with an on demand, edge-based recursive subdivision algorithm. The framework supports the use of functions implemented in external simulation packages, eliminating the need to reimplement the bases within the visualization system. We demonstrate our method on several examples, and have implemented the framework in the open-source visualization system VTK.
Hardware-accelerated 3D visualization of mass spectrometry data
Authors: Jose De Corral, Hanspeter Pfister
Published at Vis, 2005

We present a system for three-dimensional visualization of complex liquid chromatography-mass spectrometry (LCMS) data. Every LCMS data point has three attributes: time, mass, and intensity. Instead of the traditional visualization of two-dimensional subsets of the data, we visualize it as a height field or terrain in 3D. Unlike traditional terrains, LCMS data has non-linear sampling and consists mainly of tall needle-like features. We adapt the level-of-detail techniques of geometry clipmaps for hardware-accelerated rendering of LCMS data. The data is cached in video memory as a set of nested rectilinear grids centered about the view frustum. We introduce a simple compression scheme and dynamically stream data from the CPU to the GPU as the viewpoint moves. Our system allows interactive investigation of complex LCMS data with close to one billion data points at up to 130 frames per second, depending on the view conditions.
Hardware-accelerated simulated radiography
Authors: Daniel E. Laney, Steven P. Callahan, Nelson L. Max, Cláudio T. Silva, Steven Langer, Randall Frank
Published at Vis, 2005

We present the application of hardware accelerated volume rendering algorithms to the simulation of radiographs as an aid to scientists designing experiments, validating simulation codes, and understanding experimental data. The techniques presented take advantage of 32-bit floating point texture capabilities to obtain solutions to the radiative transport equation for X-rays. The hardware accelerated solutions are accurate enough to enable scientists to explore the experimental design space with greater efficiency than the methods currently in use. An unsorted hexahedron projection algorithm is presented for curvilinear hexahedral meshes that produces simulated radiographs in the absorption-only regime. A sorted tetrahedral projection algorithm is presented that simulates radiographs of emissive materials. We apply the tetrahedral projection algorithm to the simulation of experimental diagnostics for inertial confinement fusion experiments on a laser at the University of Rochester.
High dynamic range volume visualization
Authors: Xiaoru Yuan, Minh X. Nguyen, Baoquan Chen, David H. Porter
Published at Vis, 2005

High resolution volumes require high precision compositing to preserve detailed structures. This is even more desirable for volumes with high dynamic range values. After the high precision intermediate image has been computed, simply rounding up pixel values to regular display scales loses the computed details. In this paper, we present a novel high dynamic range volume visualization method for rendering volume data with both high spatial and intensity resolutions. Our method performs high precision volume rendering followed by dynamic tone mapping to preserve details on regular display devices. By leveraging available high dynamic range image display algorithms, this dynamic tone mapping can be automatically adjusted to enhance selected features for the final display. We also present a novel transfer function design interface with nonlinear magnification of the density range and logarithmic scaling of the color/opacity range to facilitate high dynamic range volume visualization. By leveraging modern commodity graphics hardware and out-of-core acceleration, our system can produce an effective visualization of huge volume data.
High performance volume splatting for visualization of neurovascular data
Authors: Fernando Vega Higuera, Peter Hastreiter, Rudolf Fahlbusch, Günther Greiner
Published at Vis, 2005

A new technique is presented to increase the performance of volume splatting by using hardware accelerated point sprites. This allows creating screen aligned elliptical splats for high quality volume splatting at very low cost on the GPU. Only one vertex per splat is stored on the graphics card. GPU generated point sprite texture coordinates are used for computing splats and per-fragment 3D-texture coordinates on the fly. Thus, only 6 bytes per splat are stored on the GPU and vertex shader load is 25% in comparison to applying textured quads. For eight predefined viewing directions, depth-sorting of the splats is performed in a pre-processing step where the resulting indices are stored on the GPU. Thereby, there is no data transfer between CPU and GPU during rendering. Post-classificative two dimensional transfer functions with lighting for scalar data and tagged volumes were implemented. Thereby, we focused on the visualization of neurovascular structures, where typically no more than 2% of the voxels contribute to the resulting 3D-representation. A comparison with a 3D-texture-based slicing algorithm showed frame rates up to 11 times higher for the presented approach on current CPUs. The presented technique was evaluated with a broad medical database and its value for highly sparse volume visualization is shown.
HOT-lines: tracking lines in higher order tensor fields
Authors: Mario Hlawitschka, Gerik Scheuermann
Published at Vis, 2005

Tensors occur in many areas of science and engineering. Especially, they are used to describe charge, mass and energy transport (i.e. electrical conductivity tensor, diffusion tensor, thermal conduction tensor resp.) If the locale transport pattern is complicated, usual second order tensor representation is not sufficient. So far, there are no appropriate visualization methods for this case. We point out similarities of symmetric higher order tensors and spherical harmonics. A spherical harmonic representation is used to improve tensor glyphs. This paper unites the definition of streamlines and tensor lines and generalizes tensor lines to those applications where second order tensors representations fail. The algorithm is tested on the tractography problem in diffusion tensor magnetic resonance imaging (DT-MRI) and improved for this special application.
Illuminated lines revisited
Authors: Ovidio Mallo, Ronald Peikert, Christian Sigg, Filip Sadlo
Published at Vis, 2005

For the rendering of vector and tensor fields, several texture-based volumetric rendering methods were presented in recent years. While they have indisputable merits, the classical vertex-based rendering of integral curves has the advantage of better zooming capabilities as it is not bound to a fixed resolution. It has been shown that lighting can improve spatial perception of lines significantly, especially if lines appear in bundles. Although OpenGL does not directly support lighting of lines, fast rendering of illuminated lines can be achieved by using basic texture mapping. This existing technique is based on a maximum principle which gives a good approximation of specular reflection. Diffuse reflection however is essentially limited to bidirectional lights at infinity. We show how the realism can be further increased by improving diffuse reflection. We present simplified expressions for the Phong/Blinn lighting of infinitesimally thin cylindrical tubes. Based on these, we propose a fast rendering technique with diffuse and specular reflection for orthographic and perspective views and for multiple local and infinite lights. The method requires commonly available programmable vertex and fragment shaders and only two-dimensional lookup textures.
Illustration and photography inspired visualization of flows and volumes
Authors: Nikolai A. Svakhine, Yun Jang, David S. Ebert, Kelly P. Gaither
Published at Vis, 2005

Understanding and analyzing complex volumetrically varying data is a difficult problem. Many computational visualization techniques have had only limited success in succinctly portraying the structure of three-dimensional turbulent flow. Motivated by both the extensive history and success of illustration and photographic flow visualization techniques, we have developed a new interactive volume rendering and visualization system for flows and volumes that simulates and enhances traditional illustration, experimental advection, and photographic flow visualization techniques. Our system uses a combination of varying focal and contextual illustrative styles, new advanced two-dimensional transfer functions, enhanced Schlieren and shadowgraphy shaders, and novel oriented structure enhancement techniques to allow interactive visualization, exploration, and comparative analysis of scalar, vector, and time-varying volume datasets. Both traditional illustration techniques and photographic flow visualization techniques effectively reduce visual clutter by using compact oriented structure information to convey three-dimensional structures. Therefore, a key to the effectiveness of our system is using one-dimensional (Schlieren and shadowgraphy) and two-dimensional (silhouette) oriented structural information to reduce visual clutter, while still providing enough three-dimensional structural information for the user's visual system to understand complex three-dimensional flow data. By combining these oriented feature visualization techniques with flexible transfer function controls, we can visualize scalar and vector data, allow comparative visualization of flow properties in a succinct, informative manner, and provide continuity for visualizing time-varying datasets.
Illustration-inspired techniques for visualizing time-varying data
Authors: Alark Joshi, Penny Rheingans
Published at Vis, 2005

Traditionally, time-varying data has been visualized using snapshots of the individual time steps or an animation of the snapshots shown in a sequential manner. For larger datasets with many time-varying features, animation can be limited in its use, as an observer can only track a limited number of features over the last few frames. Visually inspecting each snapshot is not practical either for a large number of time-steps. We propose new techniques inspired from the illustration literature to convey change over time more effectively in a time-varying dataset. Speedlines are used extensively by cartoonists to convey motion, speed, or change over different panels. Flow ribbons are another technique used by cartoonists to depict motion in a single frame. Strobe silhouettes are used to depict previous positions of an object to convey the previous positions of the object to the user. These illustration-inspired techniques can be used in conjunction with animation to convey change over time.
Illustrative display of hidden iso-surface structures
Authors: Jan Fischer, Dirk Bartz, Wolfgang Straßer
Published at Vis, 2005

Indirect volume rendering is a widespread method for the display of volume datasets. It is based on the extraction of polygonal iso-surfaces from volumetric data, which are then rendered using conventional rasterization methods. Whereas this rendering approach is fast and relatively easy to implement, it cannot easily provide an understandable display of structures occluded by the directly visible iso-surface. Simple approaches like alpha-blending for transparency when drawing the iso-surface often generate a visually complex output, which is difficult to interpret. Moreover, such methods can significantly increase the computational complexity of the rendering process. In this paper, we therefore propose a new approach for the illustrative indirect rendering of volume data in real-time. This algorithm emphasizes the silhouette of objects represented by the iso-surface. Additionally, shading intensities on objects are reproduced with a monochrome hatching technique. Using a specially designed two-pass rendering process, structures behind the front layer of the iso-surface are automatically extracted with a depth peeling method. The shapes of these hidden structures are also displayed as silhouette outlines. As an additional option, the geometry of explicitly specified inner objects can be displayed with constant translucency. Although these inner objects always remain visible, a specific shading and depth attenuation method is used to convey the depth relationships. We describe the implementation of the algorithm, which exploits the programmability of state-of-the-art graphics processing units (GPUs). The algorithm described in this paper does not require any preprocessing of the input data or a manual definition of inner structures. Since the presented method works on iso-surfaces, which are stored as polygonal datasets, it can also be applied to other types of polygonal models.
Interactive rendering of large unstructured grids using dynamic level-of-detail
Authors: Steven P. Callahan, João Luiz Dihl Comba, Peter Shirley, Cláudio T. Silva
Published at Vis, 2005

We describe a new dynamic level-of-detail (LOD) technique that allows real-time rendering of large tetrahedral meshes. Unlike approaches that require hierarchies of tetrahedra, our approach uses a subset of the faces that compose the mesh. No connectivity is used for these faces so our technique eliminates the need for topological information and hierarchical data structures. By operating on a simple set of triangular faces, our algorithm allows a robust and straightforward graphics hardware (GPU) implementation. Because the subset of faces processed can be constrained to arbitrary size, interactive rendering is possible for a wide range of data sets and hardware configurations.
Interactive visual analysis and exploration of injection systems simulations
Authors: Kresimir Matkovic, Mario Jelovic, Josip Juric, Zoltan Konyha, Denis Gracanin
Published at Vis, 2005

Simulations often generate large amounts of data that require use of SciVis techniques for effective exploration of simulation results. In some cases, like 1D theory of fluid dynamics, conventional SciVis techniques are not very useful. One such example is a simulation of injection systems that is becoming more and more important due to an increasingly restrictive emission regulations. There are many parameters and correlations among them that influence the simulation results. We describe how basic information visualization techniques can help in visualizing, understanding and analyzing this kind of data. The Com Vis tool is developed and used to analyze and explore the data. Com Vis supports multiple linked views and common information visualization displays such as 2D and 3D scatter-plot, histogram, parallel coordinates, pie-chart, etc. A diesel common rail injector with 2/2 way valve is used for a case study. Data sets were generated using a commercially available AVL HYDSIM simulation tool for dynamic analysis of hydraulic and hydro-mechanical systems, with the main application area in the simulation of fuel injection systems.